EXPERIMENTAL INVESTIGATION OF
THERMOCHEMICALLY-DERIVED FUELS IN A
DIESEL ENGINE
Md Farhad Hossain
Masters of Science (Mechanical Engineering)
Khulna University of Engineering & Technology (KUET), Bangladesh.
Supervisors:
Professor Richard Brown
Senior Lecturer Dr. Thomas Rainey
Professor Zoran Ristovski
A thesis by publication submitted in fulfilment of the requirements for the
Degree of Doctor of Philosophy (PhD)
Chemistry, Physics and Mechanical Engineering School
Science and Engineering Faculty
Queensland University of Technology
2018
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine ii
Statement of Original Authorship
The work contained in this thesis has not been previously submitted to meet
requirements for an award at this or any other higher education institution. To the best
of my knowledge and belief, the thesis contains no material previously published or
written by another person except where due reference is made.
Signature: QUT Verified Signature
Date: January 2018
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine iii
Abstract
There is a growing demand for transport liquid fuel and industrialised countries
have already started to use alternative fuels as substitutes for fossil fuel. Many highly-
innovative technologies have achieved early commercial status for alternative liquid
fuel production. One such technology is the thermochemical conversion process,
which can convert a wide range of alternative feedstocks into fuels without pre-
treatment, thereby reducing the production cost of the fuel. Hydrothermal liquefaction
(HTL) and pyrolysis methods are commonly used as thermochemical processes to
produce alternative fuels.
This research focuses on thermochemical conversion of feedstocks and is
divided into two streams. The first investigates the use of wet microalgae feedstocks,
using HTL, to produce biocrude. The second stream explores the use of dry waste tyre
feedstocks using Green Distillation Technology (GDT), a modified pyrolysis process,
to make tyre oil.
In the first stream, wet microalgae feedstock was used to produce biocrude via
the HTL method. The impact of the fuel on a diesel engine was investigated.
Microalgae is more scalable and has greater ability to supply a significant proportion
of world energy compared to most types of biofuel feedstock. HTL is well suited to
wet biomass (such as microalgae) as it greatly reduces the energy requirements
associated with dewatering and drying. The present experimental analyses of the
physicochemical properties of biocrude oil produced via HTL uses a high-growth-rate
microalgae, Scenedesmus sp., in a large-batch reactor. Batch reactors overcome issues
with feeding against the high pressure required (200 bar) and can adapt to different
feedstocks easily. Literature relating to HTL mostly reports on work using very small-
batch reactors, which are preferred by researchers, so there are few experimental and
parametric measurements for the physical properties of biocrude such as viscosity and
density. In this study, a difference between the traditional calculated values and the
measured values was found. Under optimum conditions, even though the measured
higher-heating value (HHV) was lower (29.8 MJ kg-1), the high density (0.97–1.04 kg
L-1) of HTL biocrude and its high viscosity (70.7–73.8 mm2 s-1) made it similar enough
to marine heavy fuels that could be immediately used without further processing. The
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine iv
batch reactor would be expected to produce more compounds due to slower heat-up
and cool-down time—likely 10–20 compounds comprising aromatics and
heterocyclics. The reaction temperature was explored in the range of 280–350 °C and
biocrude oil yield and HHV reached their maxima at the highest temperature. Slurry
concentration was explored between 15–30% at this temperature and the best HHV,
O:C and N:C, was found to occur at 25%. Two solvents (dichloromethane (DCM) and
n-hexane) were used to recover biocrude oil, affecting the yield and chemical
composition of the biocrude. Biocrude obtained by HTL for green freshwater
microalgae contained 10–11% (wt.) oxygen, 4–8% (wt.) nitrogen and 32–35 MJ/kg
calorific value (20–27% lower than for petroleum diesel).
Microalgae biocrude is not suitable to use in a transport diesel vehicle due to its
high density and viscosity compared to diesel. To investigate the effect of microalgae
HTL biocrude on diesel engine performance and exhaust emissions, a surrogate fuel
was developed. The chemical compound of the surrogate fuel was selected from
microalgae HTL biocrude. Approximately 65% of microalgae biocrude chemical
compounds were blended in different proportions to prepare a surrogate fuel similar to
diesel. The engine experiment was conducted on a diesel engine in the Biofuel Engine
Research Facility (BERF) at the Queensland University of Technology (QUT).
Exhaust emissions, including particulate and gaseous emissions, were investigated and
a significant reduction was found in particle matter (PM), particle number (PN), and
Carbon monoxide (CO) for all 10%, 20% and 50% blends except NOx, which
increased around 15–20% when compared to diesel fuel. There were no significant
changes found with microalgae HTL surrogate blends in the engine performance
parameters, including brake power (BP), brake mean effective pressure (BMEP) and
brake thermal efficiency (BTE).
In the second stream, waste-tyre feedstock was used to produce oil using the
GDT method and the impact of that fuel on a diesel engine was investigated. Globally,
there is a growing problem of waste-tyre disposal. End-of-life tyres (ELTs) are a
significant and growing environmental hazard. Around one billion waste tyres are
generated worldwide every year. This total is expected to increase to 1.5 billion by
2020. Therefore, waste-disposal-tyre-to-fuel technology offers a very promising
solution for both issues. The tyres are an organic waste from which useful energy in
the form of liquid, gas or solid, can be derived. Meanwhile, the calorific values of
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine v
rubber from tyres are 35–40 MJ/kg, so vehicle tyres appear a very promising feedstock
for fuel. Hence, such a solution is most effective and useful as it not only resolves the
challenge of waste tyre management but also provides output that can be further used
in a wide range of applications including diesel engine as a transport fuel. The
physiochemical properties of the GDT-tyre oil are like diesel fuel and the fuel can be
mixed with diesel in any blend ratio. The engine experiment was conducted with a
diesel engine in the Biofuel Engine Research Facility (BERF) at QUT. A substantial
change was found in NOx emissions, which cut off around 30% for both 10% and 20%
blends when compared to diesel fuel. PM and PN were reduced by 35%–60% and 5–
20% respectively for both blends and CO increased by around 2%–3% with respect to
diesel emissions. No significant changes were found in engine performance parameters
with GDT-tyre-oil blends.
Thus, this study represents a significant contribution to the existing literature by
evaluating two different thermochemical conversion methods. This is the first time
microalgae HTL surrogate fuel has been tested in a diesel engine. Similarly, this is first
time the engine performance and exhaust emissions of GDT-tyre oil have been tested.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine vi
Table of Contents
Statement of Original Authorship ............................................................................................ ii
Abstract ................................................................................................................................... iii
Table of Contents .................................................................................................................... vi
List of Figures ....................................................................................................................... viii
List of Tables ........................................................................................................................... xi
Keywords ............................................................................................................................... xii
List of Acronyms ................................................................................................................... xiii
Acknowledgements ................................................................................................................ xv
List of Publications ............................................................................................................... xvii
Chapter 1: Introduction .................................................................................... 21
1.1 Background and motivation ......................................................................................... 21
1.2 research objectives ....................................................................................................... 25
1.3 Research questions ....................................................................................................... 26
1.4 Research approach ....................................................................................................... 28
Chapter 2: Contribution of thesis ..................................................................... 30
Chapter 3: Literature review on diesel engine performance using microalgae
FAME and the prospects of HTL biocrude ........................................................... 33
3.1 introduction .................................................................................................................. 37
3.2 Microalgae biomass to biofuel conversion technologieS ............................................. 38
3.3 Engine performance and emissions .............................................................................. 46
3.4 Conclusion ................................................................................................................... 52
3.5 Acknowledgements ...................................................................................................... 52
Chapter 4: Literature review on thermochemical conversion of waste
tyres .......................................................................................................... 53
4.1 Introduction .................................................................................................................. 54
4.2 Waste tyre to oil using thermochemical conversion .................................................... 55
4.3 Waste Tyre to oil, carbon and steel .............................................................................. 58
4.4 Diesel engine performance and exhaust emission using tyre oil.................................. 60
4.5 Conclusion ................................................................................................................... 62
Chapter 5: Experimental measurements of physical and chemical properties
of microalgae biocrude using a large-batch reactor ............................................. 63
5.1 Introduction .................................................................................................................. 67
5.2 Materials and methods ................................................................................................. 69
5.3 Results and discussion ................................................................................................. 72
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine vii
5.4 Conclusion ....................................................................................................................85
5.5 Acknowledgments ........................................................................................................86
Chapter 6: Investigation of microalgae HTL fuel effects on diesel engine
performance and exhaust emissions using surrogate fuels .................................. 87
6.1 Introduction ..................................................................................................................91
6.2 Concept of microalgae HTL surrogate .........................................................................93
6.3 Materials and methods ................................................................................................100
6.4 Results and discussion ................................................................................................104
6.5 Conclusion ..................................................................................................................120
6.6 Acknowledgements.....................................................................................................121
Chapter 7: Investigation of diesel engine performance and exhaust emissions
using tyre oil ........................................................................................................ 123
7.1 Introduction ................................................................................................................127
7.2 fuel production and preparation ..................................................................................128
7.3 Materials and Methods ...............................................................................................129
7.4 Results and discussion ................................................................................................132
7.5 Conclusion ..................................................................................................................146
7.6 Acknowledgements.....................................................................................................147
Chapter 8: Conclusions and Recommendations ........................................... 149
8.1 Conclusion ..................................................................................................................149
8.2 Application of outcomes .............................................................................................152
8.3 Limitations ..................................................................................................................152
8.4 Recommendations and future studies .........................................................................153
Bibliography ........................................................................................................... 156
Appendices .............................................................................................................. 171
Biofuel engine research FACILITY (BERF) at QUT ...........................................................171
APPENDIX A: Microalgae HTL biocrude production .........................................................172
APPENDIX B: Fuel Certificate ............................................................................................173
APPENDIX C: Diesel engine performance with surrogate blends .......................................175
APPENDIX D: Diesel engine performance tyre-oil blends ..................................................179
APPENDIX E: Biofuel engine research FACILITY (BERF) at QUT..................................182
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine viii
List of Figures
Figure 1.1: Conceptual flow chart of dissertation. ..................................................... 29
Figure 3.1: Classification microalgae conversion processes [60]. ............................. 39
Figure 3.2: Solvent-extraction and transesterification SET process. ......................... 40
Figure 3.3: HTL process and product separation [33]. .............................................. 41
Figure 4.1: Thermal cracking of waste tyre [158]. ..................................................... 58
Figure 5.1: HTL product recovery workflow. ............................................................ 70
Figure 5.2: Effect of solvent on the recovery of biocrude, solids and gas +
aqueous components after HTL treatment (350 °C, 60 min, 25% slurry
concentration). .............................................................................................. 73
Figure 5.3: Influence of the reaction temperature on product yields at 25%
solids concentration and 60 min reaction time in a nitrogen
atmosphere (2 bar at commencement), values are for yield data. ................ 74
Figure 5.4: Effect of slurry concentration on the recovery of biocrude, solids
and gas + aqueous components after HTL treatment (350 °C, 60 min).
Standard deviations are based on 2 replicates; values provided are for
yield data. ..................................................................................................... 75
Figure 5.5: Van Krevelen diagram of biocrudes gained for different
temperatures (280, 300 and 350 °C) and slurry concentrations (15%,
20% and 30%) in comparison with diesel and FAME biodiesel
standards [196]. ............................................................................................ 81
Figure 6.1: Weight percentage of chemical compounds in microalgae HTL
biocrude. ....................................................................................................... 94
Figure 6.2: Major chemical compounds of microalgae HTL biocrude [215]. ........... 94
Figure 6.3: Chemical structure of (a)1,4 dimethyl, benzene and (b)
Ethylbenzene. ............................................................................................... 95
Figure 6.4: Chemical structure of (a) 3-methyl, 2-cyclopenten-1-one, (b) 2,3-
dimethyl, 2-cyclopenten-1-one and (c ) Cyclopentene. ............................... 96
Figure 6.5: Chemical structure of undecane. .............................................................. 96
Figure 6.6: Chemical structure of (a) 4-hydroxy-4-methyl and (b) butanol. ............ 97
Figure 6.7: Chemical structure of di-(2-propylpentyl) ester. ..................................... 97
Figure 6.8: Proposed roadmap for development of microalgae HTL surrogate
fuels. ............................................................................................................. 99
Figure 6.9: Percentage of chemical compound of a new microalgae HTL
surrogate. ...................................................................................................... 99
Figure 6.10: Blended microalgae HTL surrogate for engine test. ............................ 100
Figure 6.11: Schematic diagram of the engine exhaust measurement system
used for this study. ..................................................................................... 104
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine ix
Figure 6.12: IP and BP variation with IMEP for different fuels. ............................. 105
Figure 6.13: BTE and BSFC variation with IMEP for different fuels. .................... 106
Figure 6.14: ITE and ISEC variation with IMEP for different fuels. ...................... 107
Figure 6.15: Variation of pressure with crank angle for 100% load for different
fuels. ........................................................................................................... 109
Figure 6.16: Variation of pressure with crank angle for 50% load for different
fuels. ........................................................................................................... 109
Figure 6.17: Variation of pressure with crank angle for 100% load for different
fuels. ........................................................................................................... 110
Figure 6.18: Variation of pressure with crank angle for 50% load for different
fuels. ........................................................................................................... 110
Figure 6.19: Effect of Microalgae HTL surrogate blended fuels on peak
pressure and rate of pressure rise. .............................................................. 111
Figure 6.20: Effect of Microalgae HTL surrogate blended fuels on boost
pressure. ..................................................................................................... 112
Figure 6.21: Brake-specific nitrogen dioxide (NO2) emissions for four different
load. ............................................................................................................ 113
Figure 6.22: Brake-specific nitrogen oxide (NOx) emissions for four different
loads. .......................................................................................................... 114
Figure 6.23: Percentage increases of NOx emissions compared to reference
diesel. ......................................................................................................... 114
Figure 6.24: Brake-specific CO emissions for four different loads. ........................ 115
Figure 6.25: Percentage reduction of CO emissions compared to reference
diesel. ......................................................................................................... 115
Figure 6.26: Variation of brake-specific particulate mass for different loads. ........ 117
Figure 6.27: Percentage of reduction of particulate mass emissions compared to
reference diesel. ......................................................................................... 117
Figure 6.28: Variation of brake-specific PN for four different loads. ..................... 118
Figure 6.29: Percentage reduction of PN emissions compared to reference
diesel. ......................................................................................................... 118
Figure 7.1: Schematic diagram of the engine exhaust measurement system used
for this study. ............................................................................................. 132
Figure 7.2: IP and BP variation with IMEP for three different fuels. ...................... 133
Figure 7.3: BTE and BSFC variation with IMEP for three different fuels. ............. 135
Figure 7.4: ITE and ISEC variation with IMEP for three different fuels. ............... 135
Figure 7.5: Variation of cylinder pressure with crank angle at 100% load for
three different fuels. ................................................................................... 137
Figure 7.6: Variation of cylinder pressure with crank angle at 50% load for
three different fuels. ................................................................................... 137
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine x
Figure 7.7: Variation of cylinder pressure with volume at 100% load for three
different fuels. ............................................................................................ 138
Figure 7.8: Variation of cylinder pressure with volume at 50% load for three
different fuels. ............................................................................................ 139
Figure 7.9: Effect of tyre oil on peak pressure. ........................................................ 140
Figure 7.10: Brake-specific NO2 emissions for four different loads. ....................... 142
Figure 7.11: Brake-specific NOx emissions for four different loads. ....................... 142
Figure 7.12: Brake-specific CO emissions for four different loads. ........................ 143
Figure 7.13: Variation of brake-specific PM emissions for different loads. ............ 145
Figure 7.14: Variation of brake-specific PN emissions for four different loads. ..... 145
Figure 8.1: Microalgae hybrid conversion process. ................................................. 153
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine xi
List of Tables
Table 3.1: Influence of fuel properties on heavy-duty diesel emissions [57, 81,
82]. ............................................................................................................... 42
Table 3.2: Solvent-extraction microalgae biofuel properties [3, 86, 87]. .................. 44
Table 3.3: Elemental analysis and HHV of microalgae HTL biocrude. .................... 45
Table 3.4: FAME versus HTL microalgae biofuel properties in comparison
with conventional diesel and HFO. .............................................................. 46
Table 3.5: Influence of microalgae biodiesel (FAME) on exhaust emissions
[116]. ............................................................................................................ 48
Table 3.6: Qualitative comparison between microalgae HTL biocrude and
HFO.............................................................................................................. 50
Table 3.7: Exhaust emissions for different ocean-going vessel using
HFO/MFO/residual. ..................................................................................... 51
Table 4.1: Major components of tyres [135, 137, 140, 141]. ..................................... 55
Table 4.2 Collection of pyrolysis reactors and product yield from the pyrolysis
of waste tyres. .............................................................................................. 57
Table 4.3: Physicochemical properties of tyre oil, WCBD and diesel. ..................... 59
Table 4.4: Properties of waste-tyre chars. .................................................................. 60
Table 5.1: Microalgae proximate and ultimate analyses data. ................................... 71
Table 5.2: Major compounds of recovered bio-oils obtained from HTL (350
°C, 60 min, 2 bar nitrogen atmosphere) using two different extraction
solvents (DCM and n-hexane). .................................................................... 77
Table 5.3: Major compounds of recovered bio-oils obtained from HTL under
various solid concentrations and temperature using (DCM). ...................... 78
Table 5.4: Ultimate analysis and HHV of the microalgae biocrude. ......................... 80
Table 5.5: Comparison of chemical and physical properties of biocrude
produced at 350 °C and 25% solids with trans-esterified microalgae
biodiesel, diesel, biodiesel and marine fuels standards [52]. ....................... 82
Table 5.6: Comparison of results from this study with literature. ............................. 84
Table 6.1: Test engine specification. ....................................................................... 101
Table 6.2: Properties of diesel and surrogate chemical compounds. ....................... 102
Table 6.3: Properties of diesel, surrogate and surrogate blends. .............................. 103
Table 7.1: GDT recycled product and quantity based on tyre types [18]. ............... 129
Table 7.2: Test-engine specifications. ...................................................................... 130
Table 7.3: Properties of diesel, tyre oil and their blends. ......................................... 131
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine xii
Keywords
Alternative fuel
Biomass
Biodiesel
Biocrude
Diesel engine
Engine performance
Exhaust emissions
Fatty acid methyl esters
First generation alternative fuels
Hydrothermal liquefaction
Microalgae
Second generation alternative fuels
Tyre oil
Thermochemical conversion
Thermochemical conversion
Pyrolysis
Waste tyre
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine xiii
List of Acronyms
Abbreviation
BP Brake Power
BMEP Brake Mean Effective Pressure
BTE Brake Thermal Efficiency
BSFC Brake-Specific Fuel Consumption
CI Compression Ignition
CN Cetane Number
CO Carbon Monoxide
DCM Dichloromethane
DOP Dioctyl phthalate
ELT End-of-life Tyre
FAME Fatty Acid Methyl Esters
GC-MS Gas Chromatography with Mass Spectroscopy
GHG Greenhouse Gas
GDT Green Distillation Technology
HTL Hydrothermal Liquefaction
HFO Heavy Fuel Oil
HHV Higher-Heating Value
HC Hydrocarbon
IC International Combustion
IP Indicated Power
IMEP Indicated Mean Effective Pressure
ITE Indicated Thermal Efficiency
ISFC Indicated Specific Fuel Consumption
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine xiv
LFO Light Fuel Oil
LHV Lower Heating Value
MFO Marine Fuel Oil
NOx Nitrogen Oxide
PM Particulate Matter
PN Particle Number
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine xv
Acknowledgements
The completion of this PhD is attributed to the immense support received from
numerous QUT members. I am tremendously grateful to my advisor and Principal
Supervisor, Professor Richard Brown, for his continuing support, guidance and
encouragement throughout my PhD and beyond. Professor Richard Brown kept me on
track whilst allowing me the freedom to explore my ideas. I am also very grateful for
receiving huge support from my multi-disciplinary supervisory team. Along with
Professor Richard Brown, Professor Zoran Ristovski was the other Chief Investigator
on this project. Professor Zoran Ristovski was mainly involved with the exhaust
emissions of the diesel engine in this research. Together with Professor Richard Brown
and Professor Zoran Ristovski, Dr Thomas Rainey was also involved in the microalgae
fuel preparation and analysis in this research. Dr Thomas Rainey also assisted me to
implement my research ideas and gave me support in designing this thesis.
I would like to thank Green Distillation Technology Corporation (GDTC) and
Trevor Bayley (Chief Operating Officer of GDTC) for their support of the tyre-oil
project. GDTC were very supportive of my work and I look forward to continued good
relations with them and the possibility of further research. I wish to thank to Michelle
Bayley for volunteer English proofreading.
I would like to acknowledge Dr Tim Bodisco, Dr Md Mostafizur Rahman, Dr Md
Nurun Nabi, Dr Md Jahirul Islam, Dr Kabir Adewale Suara, Dr Md Aminul Islam, Dr
Ali Zare, Ashrafur Rahman, Thuy Chu Van and Mohammad Jafari for their assistance
with reviewing the manuscripts that have been published as part of this PhD project. I
also wish to thank to Zoe Staines for English proofreading. I would like to extend my
great thanks to Niki Widdowson, Denis Randall, and Dennis Rutzou for their help in
the waste-tyre oil project.
I would like to give special thanks to Noel Hartnett for his help conducting
experiments. I wish to also extend my gratefulness to all of the members and staff of
the Science and Engineering Faculty and Engineering Precinct, as well as Richard’s
final project students for their ongoing support of my candidature and research.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine xvi
I acknowledge the financial support received from QUT, via QUT’s
postgraduate research scholarships (QUT-PRA). I would also like to give thanks to the
QUT Central Analytical Research Facility for their assistance.
My heartfelt thanks go to my family. This work couldn’t have been completed
without their pure devotion, sacrifice and continued prayers towards my success. Their
encouragements kept me going when there seemed to be no way forward. In particular,
I would like to extend my heartfelt thanks to my wife, Nazia Zabin, for her steady
mental support, consideration, patience, help, and encouragement.
Finally, I wish to thank my colleagues and friends in QUT and Brisbane for
their moral support. In the same way, I wish to give my sincere appreciation to my
parents, my sister and Mentor for their guidance.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine xvii
List of Publications
Papers directly related to this thesis are numbered below:
PEER-REVIEWED JOURNALS
(1) Hossain F.M., Rainey T.J., Ristovski Z., Brown R.J. Performance and
exhaust emissions of vehicle and marine compression ignition engines using
microalgae FAME and the prospects for microalgae HTL biocrude, Renewable and
Sustainable Energy Review, Available online 16 June 2017.
This research article is related to objective 1 and chapter 3 of this thesis;
(2) Hossain F.M., Kosinkova J., Brown R.J., Ristovski Z., Stephens E.,
Hankamer B., Rainey T.J. Experimental Investigations of Physical and Chemical
Properties for Microalgae HTL Bio-Crude Using a Large Batch Reactor. Energies,
2017, 10(4): p. 467.
This research article is related to objectives 1, 2 and chapter 5 of this thesis;
(3) Hossain F.M., Rainey J.T., Nabi N.M., Bodisco T., Suara K., Rahman
M.M., Rahman S., Chuvan T., Ristovski., and Brown R.J. Development of new series
microalgae HTL surrogate fuels and their influence on diesel engine performance and
exhaust emissions. Journal of Energy Conversion and Management, 2017;152
(Supplement C):186-200.
This research article is related to objective 3 and chapter 6 of this thesis;
(4) Hossain F.M., Rainey, T.J., Bodisco T., Bayley T, Randall D., Ristovski Z,
Brown R.J. Investigation of diesel engine performance and emissions using tyre-oil
blends. Journal of Fuel (under review).
This research article is related to objective 4 and chapter 7 of this thesis.
PEER-REVIEWED CONFERENCES
(5) Hossain F.M., Kosinkova J., Brown R.J., Ristovski Z., Stephens E., and
Rainey T.J. The chemical-physical properties of biocrude derived from the
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine
xviii
hydrothermal liquefaction of algae. 5th International conference on Algal Biomass,
Biofuel & Bio-production 7-10 June, 2015-San Diego, USA
(6) Hossain F.M., Nabi M., Rahman M.M., Zare A., Rainey T., Stuart D.,
Ristovski Z., and Brown R.J., Experimental investigation of the effects of oxygenated
fuels on exhaust emissions in a heavy-duty diesel engine. Australian Combustion
Symposium, 7-9 December, University of Melbourne, Vic 2015:56-9.
PEER-REVIEWED POSTER
(7) Hossain F.M., Islam A., Rainey R.J., Kosinkova J., Ristovski Z, Stephens
E., Helmann K., and Brown R.J. Biofuel from microalgae: solvent-extraction Vs
liquefaction. ICFS-2015 Conference at India in 7th February 2015.
Papers that have been published during candidature as a co-author:
PEER-REVIEWED JOURNALS
Nabi MN, Zare A, Hossain FM, Bodisco TA, Ristovski ZD, Brown RJ. A
parametric study on engine performance and emissions with neat diesel and diesel-
butanol blends in the 13-Mode European Stationary Cycle. Energy Conversion and
Management 2017;148:251-9.
Nabi M.N., Rahman M.M., Islam M.A., Hossain F.M., Brooks P., Rowlands
W.N., Tulloch J., Ristovski Z., Brown R.J. Fuel. Characterisation, engine
performance, combustion and exhaust emissions with a new renewable Licella biofuel.
Energy Conversion and Management. 2015; 96:588-98.
Nabi M.N., Zare A., Hossain F.M., Rahman M.M., Bodisco T., Ristovski Z.,
and Brown R.J. Influence of fuel-borne oxygen on European Stationary Cycle: Diesel
engine performance and emissions with a special emphasis on particulate and NO
emissions. Energy Conversion and Management. 2016; 127:187-98.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine xix
Zare A, Nabi MN, Bodisco TA, Hossain FM, Rahman M, Van TC, et al. Diesel
engine emissions with oxygenated fuels: A comparative study into cold-start and hot-
start operation. Journal of Cleaner Production 2017.
Zare A., Nabi M.N., Bodisco T.A., Hossain F.M., Rahman M.M., Ristovski Z.,
and Brown R.J. The effect of triacetin as a fuel additive to waste cooking biodiesel on
engine performance and exhaust emissions. Fuel. 2016; 182:640-9.
Zare A., Bodisco T., Nabi N., Hossain F.M., Rahman M.M., Ristovski Z., and
Brown R.J. The influence of oxygenated fuels on transient and steady-state engine
emissions. Energy. 2017; 121:841-53.
Zare A, Bodisco TA, Nabi MN, Hossain FM, Ristovski ZD, Brown RJ. Engine
performance during transient and steady-state operation with oxygenated fuels. Energy
& Fuels 2017.
Jahirul MI, Brown RJ, Senadeera W, Ashwath N, Rasul MG, Rahman MM,
Hossain FM, Moghaddam L, Islam MA, O’Hara IM. Physio-chemical assessment of
beauty leaf (Calophyllum inophyllum) as second-generation biodiesel feedstock.
Energy Reports. 2015; 1:204-15.
PEER-REVIEWED CONFERENCES
Nabi N., Zare A., Hossain F. M, Rahman M.M., Stuart D., Ristovski Z., and
Brown R.J. Formulation of new oxygenated fuels and their influence on engine
performance and exhaust emissions. Proceedings of the 2015 Australian Combustion
Symposium: The Combustion Institute Australia and New Zealand Section; 2015. p.
64-7.
Zare A. Bodisco T., Nabi N., Hossain F. M., Rahman M.M., Stuart D., Ristovski
Z., and Brown R.J. Impact of Triacetin as an oxygenated fuel additive to waste cooking
biodiesel: transient engine performance and exhaust emissions. Proceedings of the
2015 Australian Combustion Symposium: The Combustion Institute Australia and
New Zealand Section; 2015. p. 48-51.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine xx
PEER-REVIEWED POSTER
Nabi N., Zare A., Hossain F.M., Rahman M.M, Ristovski Z., and Brown R.J.
Steady-state transient diesel engine test cycle: Issues associated with the introduction
of bio-fuel. ICFS-2015 Conference at India in 7th February 2015.
Chapter 1: Introduction 21
Chapter 1: Introduction
1.1 BACKGROUND AND MOTIVATION
In recent years, several highly-innovative conversion technologies have seen the
production of alternative fuels increase. Among these, many thermochemical
conversion processes have achieved commercial status due to their production of
liquid fuel [1]. Conversely, the growing demand for liquid fuel for transport around
the world mostly depends on fossil fuels and is responsible for raising the global
temperature due to pollution [2]. As a result, researches are using advanced
technologies to find alternative fuels that could be used as a substitute for fossil fuel
and reduce exhaust emissions [3-6]. Many researchers have developed different
alternative fuels, most of which are categorised as first-generation or second-
generation alternative fuels [6-8]. First-generation alternative fuels are those that have
been derived from sources such as starch, sugar, animal fats or vegetable oil. Oil is
obtained using conventional production techniques, the most common being a process
called transesterification. This process involves only a few steps from feedstock to
alternative fuel. However, the food versus fuel issue causes some debate over first-
generation fuel production. Because of this, researchers have tried to find a next-
generation fuel, i.e. second-generation fuel [8]. This differs from the first-generation
biofuels insofar as the feedstock used in producing second-generation biofuels are
generally not food crops. Second-generation biofuels are derived from different
feedstock including lignocellulosic biomass, municipal solid waste, waste tyre,
electrical waste etc. Different technology is often used to extract energy from them in
the form of fuel. In most cases, second-generation feedstock is processed differently
to first-generation biofuels, and often uses a thermochemical conversion.
However, dry extraction processes are the established methods used to separate
high-protein cake and high-added-value co-products that contribute to improve the
economic performance of the system. Chemical solvent extraction is the most common
method used to extract lipids from oil seeds. The efficiency of the solvent extraction
process is strongly dependent on the specific algae strain under consideration [9-11].
Wet-extraction processes can avoid these drying steps. In a wet pathway, cell
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 22
disruption is caused by thermochemical methods. Thermochemical conversion is the
use of heat, with or without the presence of oxygen, to convert various feedstocks into
other forms of energy. Among different thermochemical conversion processes,
pyrolysis and hydrothermal conversion are most popular because of their smooth
operation [11]. Those processes are used to transform the component into fuels along
with other related hydrocarbon (HC)-based products. The particular feedstock, for
example its size or whether it is wet or dry, is also important when selecting the
conversion technique [11]. Thermochemical methods are available for both dry and
wet feedstocks, pyrolysis being used for dry feedstocks and hydrothermal liquefaction
(HTL) for wet feedstocks.
The present research on microalgae and waste-tyre conversion falls into two
groups. The first is based on wet microalgae to biocrude using HTL and the second is
based on dry waste tyre to tyre oil using Green Distillation Technology (GDT), a
thermochemical conversion process similar to pyrolysis.
The pyrolysis process, among other similar thermochemical processes, is
assumed to be most friendly to the environment. The pyrolysis process involves the
decomposition of the second-generation feedstock into products that have lower
molecular weight in an arrangement of limited temperatures. The process involves the
decomposition of the solid at a considerably inflated temperature of around 300 °C to
900 °C in an environment that is free of oxygen and resultantly producing char, oil and
gas. Deploying this process, an important source of energy can be derived and the
resulting components can be used as a source of transport fuel. There has been great
interest in pyrolysis as a thermochemical method to process waste tyres [12]. Cumali
and Huseyin [13] experimentally investigate waste vehicle tyre to oil, using a catalytic
pyrolysis process. They found the fuel to be like fossil fuel. Martínez et al. [14]
demonstrated the waste-tyre pyrolysis process on a pilot scale in a continuous auger
reactor. A large number of research articles described pyrolysis as an attractive method
to recycle waste tyre to tyre oil, steel, and rubber [15-17]. It has many advantages,
including management of the waste-tyre disposal problem, compared to other
thermochemical processes such as combustion and gasification [16]. On the other
hand, GDT has achieved an Australian world technological breakthrough by
successfully and commercially recycling end-of-life car and truck/bus tyres (ELTs)
into the valuable commodities of oil, carbon, and steel. ELTs are a blight on the
Chapter 1: Introduction 23
environment because, until now, no means have been found to effectively and
profitably recycle them [18]. However, using a technique known as destructive
distillation, a kind of pyrolysis, GDT is able to turn this wasted resource and
environmental hazard into the high demand valuable raw materials of tyre oil, carbon,
and steel. However, the process involves dry feedstock, which may extend the length
of the process and is unsuitable for wet-biomass feedstocks.
To overcome this limitation, a HTL process could be used. Conversely, HTL is
a thermal depolymerisation method to convert wet biomass into biocrude at an elevated
temperature and pressure. HTL converts biomass into biocrude oil as well as aqueous,
gas and solid phase products at elevated pressures (5–24 MPa) and moderate
temperatures (250–400 °C). In general, the variation in the biochemical composition,
particularly the carbon-chain length and the degree of saturation, affects the conversion
rate of the HTL biocrude. HTL converts biomass into gas, liquid and solids similar to
pyrolysis, but operates at a higher pressure and at a lower temperature.
Microalgae biomass present the following advantages: rapid growth, high oil
yield per unit area, ability to grow in saline water, and an ability to be cultivated on
non-arable land [11]. The number of research studies carried out on the subject of
thermal treatment of microalgae has increased in recent years. This scientific research
has demonstrated that it is technically feasible to produce alternative fuel using
microalgae, though this approach is not economically suitable for industrial production
[19-22]. In a literature review on the processing of microalgae using a thermochemical
pathway carried out by Raheem et al. [23], it was confirmed that HTL of microalgae
was a promising technology to produce high-quality alternative fuel. There are two
key methods for obtaining biofuel from microalgae. The first is solvent extraction
followed by transesterification to produce fatty acid methyl esters (i.e. FAME
biodiesel). The second method is a thermochemical process, HTL, to produce
biocrude. The main benefits of liquefaction are that many different products can be
extended and that drying of the biomass is not required. In contrast, solvent-extraction-
processed biofuel contains only FAME and uses dry biomass. HTL biocrude does not
depend on the lipid content of the feedstock because the whole biomass is converted
into biocrude. Conversely, solvent extracted then transesterified biofuel depends on
the lipid content of the biomass. Solvent extraction is a low-pressure process but a
high-cost solvent is required, while HTL is a high-pressure process.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 24
Waste-tyre disposal is a growing problem across the world [24]. Most people are
aware that ELTs are a significant environmental hazard, but few know the extent of
the problem. It is reported that Australians generate over 51 million ELTs each year
[25], which is equal to 0.68 million tons [26]. Recently an Australian company, GDT,
developed a process to convert whole waste tyres into tyre oil as an alternative to diesel
fuel [18]. The technology reduces the full tyres to their original constituents of carbon,
steel, and tyre oil. Around one third of the total mass of waste tyres is converted to tyre
oil. The Australian Bureau of Resource and Energy Economics [27] has reported that
Australia’s petroleum consumption has reached about 64 billion litres per annum with
nearly 70% used for the transport sector in 2013. Diesel fuel holds the largest share,
which is 41% [28]. It is estimated that around 1% of diesel fuel could be replaced by
waste-tyre oil in Australia.
The physicochemical properties of biofuels are important parameters with
respect to the quality of fuels and their application. The physical properties vary with
chemical composition, including the carbon-chain length and the degree of
saturation/unsaturation. Other factors that affect fuel suitability for a conventional
engine include chemical composition, molecular structure, Cetane Number (CN), acid
value and sulphur content. Moreover, these fuel properties affect the engine performance
and exhaust emission results. Several studies have shown that fuel properties can
significantly affect engine exhaust emissions. There is widespread agreement that no
single factor is responsible for alternative fuel engine performance and the character
of exhaust emissions. Microalgae alternative fuels are considered to be a first fuel in
this research.
The chemical composition and physical properties of microalgae biocrude
produced using HTL methods were found to be different to that of diesel and biodiesel.
Therefore, the biocrude required further processing (i.e. upgrading) to improve its
quality by reducing undesired components. The authors carried out research to produce
a microalgae HTL surrogate fuel based on various chemical compounds, which gave
a GC-MS analysis of the biocrude. This research covered the selection of different
chemicals of microalgae HTL and their percentages based on the target fuel properties.
The physiochemical properties of the target fuels were considered as the design
parameters and the percentile ranges for different groups of chemicals were based on
previous research or knowledge gained from experience. The reference chemicals
Chapter 1: Introduction 25
were selected from microalgae HTL biocrude chemicals. The selected chemicals were
then blended in different proportions and measured against the design properties.
Those properties were compared with the target fuels and optimised by changing the
input parameters, for example, the percentages of different chemicals. Finally, a
surrogate fuel was prepared to test in an internal combustion (IC) diesel engine. On
the other hand, the properties of tyre oil were tested and were found to be similar to
diesel fuel in higher-heating value (HHV), viscosity, density, and CN. Before
conducting the experimental studies, a careful fuel analysis was carried out. It is
broadly accepted that fuel properties influence fuel-spray characteristics, fuel
evaporation, the formation of fuel droplet size, the distribution of fuel atoms, and,
therefore, the exhaust emissions. These features are determined by the physiochemical
property of the fuel.
However, the HTL technology required to generate alternative fuel from
microalgae and the feedstock waste-tyre oil is still in its early stages of development.
It appears that there is a considerable amount of research on microalgae biofuel
production and its use in engine tests, but none using a surrogate based on microalgae
HTL biocrude for engine tests. Similarly, there is little research on waste-tyre oil using
a pyrolysis process and its application in diesel engines and no research testing GDT-
tyre oil in turbo-charged diesel engines. This research project investigates the effects
on engine performance and exhaust emissions of adding both tyre oil and microalgae
surrogate to diesel. A more thorough investigation of HTL microalgae biocrude and
waste-tyre oil properties, as well as their effect on engine performance and emissions,
should also be researched to establish both fuels as an alternative fuel option.
1.2 RESEARCH OBJECTIVES
The initial concern of this research is the thermochemical conversion of wet
microalgae and dry waste tyre to an alternative fuel, with the help of HTL and pyrolysis
technology, respectively. It is important to identify the physicochemical properties of
alternative fuels as their quality determines their application. The physicochemical
properties of HTL microalgae alternative fuel are not suitable for a transport diesel
engine. As a result, a new surrogate fuel was developed, based on the microalgae HTL
chemical compounds that could be used for diesel engines. Conversely, the
physiochemical properties of waste-tyre pyrolysis oil was measured and found to be
suitable for use in a diesel engine. Following this, the HTL microalgae surrogate fuel
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 26
and tyre pyrolysis oil, respectively, were mixed with diesel fuel, and an experiment
was conducted in the internal combustion engine. The engine performance and exhaust
emissions of the blended microalgae HTL alternative fuel and tyre pyrolysis fuel were
compared separately with regular diesel fuel.
Objectives: This project aimed to achieve the following objectives
1. To investigate the thermochemical conversion process for wet microalgae
and dry-waste-tyre feedstock and identify key process parameters, which
affect biocrude properties.
2. To determine the critical physicochemical properties of microalgae biocrude
from the HTL process and compare them with those of FAME and petroleum
diesel.
3. To develop a surrogate fuel based on a microalgae HTL chemical compound
and investigate its diesel engine performance and exhaust emissions.
4. To investigate the physicochemical properties of waste-tyre oil and
investigate diesel engine performance and exhaust emissions, compared to
diesel fuel.
1.3 RESEARCH QUESTIONS
Four research questions (see below) were formulated from gaps in the research based
on thermochemical conversion, physicochemical properties of fuels, engine
performance and exhaust emissions. Each of these questions are carefully examined
and addressed in the remaining Chapters of this thesis.
Q1. What thermochemical conversion methods are convenient for a wide range (wet
to dry) of second-generation alternative fuel feedstocks?
In most cases, second-generation feedstock is processed differently to first-
generation biofuels using a thermochemical conversion. Thermochemical conversion
is the use of heat, with or without the presence of oxygen, to convert various feedstocks
into other forms of energy. Among different thermochemical conversion processes,
pyrolysis and hydrothermal conversion are most used for their easy of operation. Both
processes are used to transform the component into fuels along with other related HC-
Chapter 1: Introduction 27
based products. In this research, the authors experimentally investigated the
conversion of wet microalgae to biocrude using HTL and waste tyre to an alternative
fuel using a pyrolysis process.
Q2. What are the complex physicochemical properties of microalgae-obtained HTL
and how do they compare with FAME and diesel?
A microalgae HTL process for biofuel production is only a recent development
in the field of alternative fuel research. Researchers have been working with
microalgae to produce a biofuel using a solvent-extract-derived then
transesterification. More recently, researchers have been using a HTL process to
produce biofuel from microalgae. However, the physicochemical properties of
microalgae liquefaction biofuel need to be investigated. This biofuel can be used in IC
engines and has the potential to significantly change exhaust emissions. The engine
performance and exhaust emission results should be compared with diesel to modify
the HTL microalgae bio-fuel.
Q3. What properties of HTL microalgae biocrude create problems for the engine
operation and how can a surrogate be produced using selected chemical compounds
of microalgae HTL to overcome the problem and improve engine performance and
exhaust emissions?
The major challenge remaining is being able to use hydrothermal liquefied
microalgae biofuels in diesel engines. Being an alternative fuel in the transportation
sector, it provides the easiest and most crucial solution for environmental problems as
it does not require any engine modifications and reduces greenhouse gas (GHG)
emissions substantially. However, the physicochemical properties of microalgae HTL
alternative fuels are not suitable for transport engines. As a result, a new surrogate fuel
was invented using a higher percentage of some of the chemical compounds of the
microalgae HTL alternative fuel. To achieve an efficient surrogate fuel that produces
fewer emissions and more power without hindering engine operation, the
physicochemical properties must be modified.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 28
Q4. What physicochemical properties of GDT/pyrolysis tyre oil affect the diesel
engine performance and exhaust emissions?
Globally, waste-tyre disposal is a growing problem. Most people are aware that
ELTs are a significant environmental hazard, but few know the extent of the mass that
is generated each year. It has been reported that each year over one billion waste tyres
are generated worldwide and this will increase to 1.5 billion by 2020, which is a huge
problem in terms of waste disposal. Therefore, waste-disposal-tyre-to-fuel
technologies offer a very promising solution for both issues. The next major challenge
is to test current vehicle engine performance and exhaust emissions using pyrolysis
tyre oil.
1.4 RESEARCH APPROACH
This experimental research is a comparative study of thermochemical
conversion, alternative fuel physicochemical properties and a diesel engine test
between wet microalgae and waste-tyre feedstock. These experimental results are then
compared with the limited previous studies available. Some available studies focus on
microalgae HTL surrogate fuel, though no studies can be found that utilise waste-tyre
oil. The approach used in this study is as follows:
Experimentally investigate wet microalgae and waste-tyre conversion to
alternative fuel using HTL and pyrolysis as a thermochemical conversion
method.
Analyse physicochemical properties of both types of fuel and compare with
regular diesel fuel to develop an alternative fuel for diesel engines.
Develop a new surrogate fuel based on microalgae HTL chemical compounds
and investigate CI engine performance and exhaust emissions.
Investigate engine performance and exhaust emissions with waste-tyre oil and
compare the results with diesel fuel.
The objective of this research is primarily to establish suitable feedstock and
appropriate conversion technology for industrial production. Concurrently, the
physicochemical properties of the fuel are analysed with the intention of investigating
its use as an alternative transport fuel, which would reduce exhaust emissions. The
conceptual flow chart of this research is shown in Figure 1.1.
Chapter 1: Introduction 29
Chapter_1: Introduction
Thesis aim: Experimental investigation of thermochemically derived fuels in a diesel engine
Chapter_3: Literature review on hydrothermal
liquefaction of microalgae
This chapter related to objective 1 and paper 1.
Chapter_5: HTL Experiments
Microalgae HTL biocrude and its property analysis
This chapter related to objective 2 and paper 2.
Chapter_6 : Investigation of microalgae HTL fuel
effects on diesel engine performance and exhaust
emissions using surrogate fuels
This chapter related to objective 3 and paper 3.
Chapter_4: Literature review on paralysis waste
tyre to oil
Chapter_7 : Investigation of diesel engine
performance and exhaust emissions using GDT
tyre oil
This chapter related to objective 4and paper 4.
Chapter_8
Conclusions and Recommendations
Chapter_2: Research contribution
Current state of knowledge of microalgae HTL biocrude and waste tyre oil
First Stream Second Stream
IC engine testing with microalgae surrogate and waste tyre oil
Figure 1.1: Conceptual flow chart of dissertation.
Chapter 2: Contribution of thesis 30
Chapter 2: Contribution of thesis
This thesis is prepared in the form of a thesis for publication, with a total of eight
chapters. It comprises two streams, as shown in Figure 1.1. The first stream is based
on microalgae and the second is based on waste tyres. The background, motivation,
and research questions for this thesis are described in Chapter 1. The contribution of
the research and conceptual structure are presented in Chapter 2. Chapters 3, 5, and 6
are part of the first stream of the thesis and Chapters 4 and 7 are part of the second
stream of the thesis. All chapters are organised as per the conceptual chart shown in
Figure 1.1. An overview of Chapters 3–8 is included below.
Chapter 3, first stream: Chapter 3 begins with a literature review of microalgae
conversion into alternative fuel using two different methods, which the research
community has thus far focused on. These are solvent extraction and transesterification
to produce FAME biodiesel, and HTL to produce biocrude. The resulting differences
in biofuel physicochemical characteristics not only affect engine performance and
emissions but also engine selection. Most engine research relating to microalgae has
been carried out on high-speed diesel engines to investigate the performance and
exhaust emissions of FAME, whereas the HTL literature has mostly presumed
biocrude would be upgraded for such engines. This literature review provides a
detailed explanation of the conversion of microalgae into alternative fuel and its
application in a diesel engine.
This Chapter has been published as a journal paper in the ‘Journal of Renewable and
Sustainable Energy Reviews’, entitled, “Performance and exhaust emissions of diesel
engines using microalgae FAME and the prospects for microalgae HTL biocrude”,
paper 1, which is related to research objective 1.
Chapter 4, second stream: Chapter 4 introduces waste tyres as a source of alternative
fuel and explores the application of that fuel in a diesel engine. This Chapter presents
literature reviews on waste tyre statistics and their recycling status around the world.
It also reviews the thermochemical conversion of waste tyres to tyre oil by using a
pyrolysis process. Finally, the Chapter explores variances in the physicochemical
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 31
properties of waste-tyre oil due to the conversion process, which can affect diesel
engine performance and exhaust emissions.
Chapter 5, first stream: This chapter describes the experimental measurements of
physicochemical properties for a HTL biocrude from a high-growth-rate microalga,
Scenedesmus sp., using a large-batch reactor. HTL is well suited to wet biomass (such
as microalgae) as it greatly reduces the energy requirements associated with
dewatering and drying. Furthermore, batch reactors overcome issues with feeding,
despite the high pressure required (200 bar), and can change feedstocks easily. The
HTL literature mostly reports on work using very small-batch reactors, which are
preferred by researchers, so there are few experimental and parametric measurements
for the physical properties of biocrude in large-batch reactors, such as HHV, viscosity
and density. During this study, a difference between the traditional calculated values
and the measured values was noted.
This Chapter has been published as a journal paper in the ‘Journal of Energies’,
entitled, “Experimental investigations of physical and chemical properties for
microalgae HTL biocrude using a large-batch reactor”, paper 2, which is related to
research objective 2.
Chapter 6, first stream: Chapter 6 focuses on engine performance and exhaust
emission testing using a surrogate fuel of microalgae HTL. This Chapter provides the
details of surrogate fuel preparation, physicochemical properties analysis and engine
testing. The performance of microalgae surrogate alternative fuel in different blends is
compared with petroleum diesel. The gaseous emissions of all surrogate alternative
blends are also compared with petroleum diesel. This Chapter provides unique
information on microalgae surrogate alternative fuel engine performance and exhaust
emissions. In Chapter 3, it was noted that no engine tests performed with microalgae
surrogate fuel had been found. Therefore, this Chapter holds great value in the field of
alternative fuel research.
This Chapter will be submitted as a journal paper in the ‘Journal of Industrial Crops
and Products’, entitled, “Investigation of the effects of microalgae HTL surrogate fuel
on diesel engine performance and exhaust emissions”, paper 3, which is related to
research objective 3.
Chapter 2: Contribution of thesis 32
Chapter 7, second stream: This chapter focuses on engine performance and exhaust
emissions testing, using waste-tyre oil provided by GDT Corporation Ltd, Australia.
Globally there is a significant volume of ELTs that can be converted into tyre oil using
a thermochemical conversion process. Chapter 4 presents a detailed review of waste
tyre statistics across the world. The physiochemical properties of the tyre oil are similar
to diesel fuel and miscible with diesel in any blend ratio. The experimental results
showed that there was no change in engine performance using 10% and 20% blend
tyre oil as well as showing a reduction in exhaust emissions. It was the first time this
fuel has been used in a diesel engine test and analysed as an alternative fuel.
Consequently, this Chapter also makes a valuable contribution to this field of fuel
research.
This Chapter will be submitted as a journal paper in the ‘Journal of FUEL’ entitled,
“Engine performance, combustion and exhaust emissions using diesel and biodiesel
with tyre oil”, paper 4, which is related to research objective 4.
Chapter 8: Chapter 8 concludes the thesis with a summary of the original
contributions and proposes possible directions for future research.
Chapter 3: Literature review on diesel engine performance using microalgae FAME and the prospects of HTL
biocrude 33
Chapter 3: Literature review on diesel
engine performance using
microalgae FAME and the
prospects of HTL biocrude
Title: Performance and exhaust emissions of diesel engines using
microalgae FAME and the prospects for microalgae HTL biocrude
Farhad M. Hossain*1, 2, Thomas J. Rainey1, 2, Zoran Ristovski1, 2, 3,
Richard J. Brown1, 2, 3
1Biofuel Engine Research Facility, Queensland University of Technology (QUT),
Brisbane, Queensland 4001, Australia
2School of Chemistry, Physics and Mechanical Engineering, QUT
3 International Laboratory for Air Quality and Health, QUT
* Corresponding author
Contact: Md Farhad Hossain
Email: [email protected], [email protected]
Postal address: GPO Box 2432, 2 George St, Brisbane, QLD 4001, Australia
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 34
Statement of contribution of Co-Authors for this publication
The authors listed in the table below have certified that:
1. They meet the criteria for authorship in that they have participated in the conception, execution, or
interpretation, of at least that part of the publication in their field of expertise;
2. They take public responsibility for their part of the publication, except for the responsible author who
accepts overall responsibility for the publication;
3. There are no other authors of the publication according to these criteria;
4. Potential conflicts of interest have been disclosed to (a) granting bodies, (b) the editor or publisher of
journals or other publications, and (c) the head of the responsible academic unit, and
5. They agree to the use of the publication in the student’s thesis and its publication on the Australasian
Research Online database consistent with any limitations set by publisher requirements.
Title and status: Performance and exhaust emissions of diesel engines using
microalgae FAME and the prospects for microalgae HTL biocrude, (Published at
Renewable and Sustainable Energy Reviews)
Contributor Statement of contribution
Md Farhad Hossain Candidate
Design concept of the article, wrote the manuscript and acted as the
corresponding author.
Signature
Date
Richard J. Brown Principal Supervisor
Professor Richard Brown is a mechanical engineer, he is a leading expert
in thermodynamics and environmental fluid mechanics, particularly in
relation to internal combustion engine performance and emissions.
Design concept, reviewed material related to engine performance and
edited the manuscript.
Zoran Ristovski Associate Supervisor
Professor. Zoran Ristovski is a physicist who works at Queensland
University of Technology as one of the leading researchers on vehicle
emissions with a special focus on particulate vehicle emissions.
Reviewed the manuscript in the section of engine exhaust emissions.
Thomas J. Rainey Associate Supervisor
Dr. Thomas Rainey has 15 years of industrial and research experience in
biomass processing particularly in pulp and paper and sugar processing.
His research focuses on bioenergy and related value-added products.
Chapter 3: Literature review on diesel engine performance using microalgae FAME and the prospects of HTL
biocrude 35
Design concept, reviewed and edited the manuscript in the section related
to biofuel production.
Principal Supervisor Confirmation
I have sighted email or other correspondence from all Co-authors confirming their certifying authorship.
Professor Richard J. Brown
Name Signature Date
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 36
Abstract:
Microalgae have attracted recent attention due to their potential as a second-
generation biofuel. This article compares and contrasts two key methods the research
community is focussing on to obtain biofuel from microalgae, namely solvent
extraction followed by transesterification, to produce fatty acid methyl esters (i.e.
FAME biodiesel), and hydrothermal liquefaction (HTL) to produce biocrude. The
resulting differences in biofuel physicochemical characteristics not only affect engine
performance and emissions but also engine selection. Most engine research relating to
microalgae has been carried out on high-speed Compression Ignition (CI) engines to
investigate the performance and exhaust emissions of FAME, whereas the HTL
literature has mostly presumed biocrude would be upgraded for similar engines.
However, growing awareness of the significant contribution of shipping emissions to
public health brings into focus alternatives to heavy-fuel oil (HFO) for low-speed CI
(marine) engines. Microalgae FAME contains about 10.5–11 % (wt.) oxygen and
36.2–39.2 MJ/kg calorific value, (10–15% lower than for petroleum diesel). When
tested in high-speed CI engines, microalgae FAME generally decreases particulate
emissions but there is a small penalty in terms of engine power owing to the high
oxygen content and lower higher-heating value (HHV). Conversely, biocrude obtained
by HTL for green freshwater microalgae contained 10–11% (wt.) oxygen, 4–8% (wt.)
nitrogen and 32–35 MJ/kg calorific value (20–27% lower than for petroleum diesel).
HTL biocrude would be expected to reduce exhaust emissions for low-speed marine
CI engines compared to HFO, especially soot emissions due to their very low sulphur
content, although NOx emissions may increase. HTL biocrude may reduce the engine
performance in terms of output power compared to HFO due to the higher oxygen
content and lower HHV. The aim of this article is to review and compare microalgae
FAME and HTL biocrude and their suitability for high- and low-speed CI engines in
terms of engine performance and emissions.
Keywords: Biodiesel, microalgae, HTL, FAME, CI Engine, emissions
Chapter 3: Literature review on diesel engine performance using microalgae FAME and the prospects of HTL
biocrude 37
3.1 INTRODUCTION
Renewable biofuel has become a key issue in the modern world due to fossil fuel
reserve depletion, increasing fuel prices and exhaust emissions [29]. Compared to
diesel, biofuel has a generally favourable combustion emission profile, including
lower emissions of carbon monoxide (CO), particulate matter and unburned
hydrocarbons [30, 31], however, NOx may increase. Microalgae have recently
received a lot of attention to produce biofuel as a renewable feedstock because of its
potential for mass production on non-arable land [2, 10, 32-35]. They are also not
highly compatible with bioethanol, which has been the focus of much research in
recent years. Although numerous conversion technologies exist, biofuel properties
vary significantly, even when the same feedstock is used [32, 36-38]. With regards to
using microalgae to make biofuel for Compression Ignition (CI) engines (i.e. diesel
engines), there has been significant recent interest in two conversion technologies.
Firstly, microalgae can be solvent extracted to recover lipids, which
subsequently undergo a traditional transesterification reaction to produce fatty acid
methyl esters (i.e. FAMEs)—normally known as biodiesel. However, for microalgae,
the raw material should be dried (at considerable expense) prior to the solvent
extraction. Microalgae FAMEs have a large variance in chemical composition due to
the feedstock [6, 35, 39]. Hussain et al. [40] tested lipid profiling and corresponding
biofuel properties of Mortierella isabellina microalgae using different drying and
extraction methods and found that differences in chemical composition of the lipids
were obtained for the same species [6, 41-43]. Islam [10] found that the
physicochemical properties of the FAME also varied with microalgae species.
A second method undergoing intensive research is HTL, which can utilise wet
biomass to produce a biocrude [44-47]. HTL converts biomass into gas, liquid and
solids similar to pyrolysis [48], but operates at a higher pressure (up to 300 bar) and at
a lower temperature between 250 °C and 350 °C [47, 49]. There have been some
investigations into converting microalgae into biofuels via HTL [33, 50-54]. HTL has
been investigated with a wide range of microalgae feedstocks, including laboratory
and commercially grown strains of Botryococcus braunii [55], Spirulina and
Tetraselmic sp. [32, 47]. Jena et al. [49] tested Spirulina platensis using HTL for
biocrude production and found the operating conditions varied the chemical
composition. The energy balance and CO2 mitigating effect of liquid fuel production
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 38
from microalgae by HTL has been reported by Sawayama et al. [56]. Eboibi et al. [47]
found that up to 65 % (wt.) biocrude oil could be obtained by HTL [47]. However,
their experimental work found that the HTL biocrude properties were dissimilar to
diesel and biodiesel and closer to that of HFO, which is used for low-speed marine
diesel engines. Consequently, the target application for HTL biocrude needs further
investigation depending on the physicochemical properties of the fuel [57].
There are two types of diesel engines high speed and low speed. The main
difference is fuel type. High-speed diesel engines use low-density and cleaner fuel (e.g.
diesel), whereas low-speed diesel engines use high-density and impure fuels (e.g.
HFO/HTL). High-speed diesel engines are used for vehicles and portable power
generators and are run using diesel or biodiesel. Conversely, low-speed diesel engines
are used for industrial power plants, marine ship engines, and are run by various grades
of HFO. However, most researchers have only used high-speed diesel engines to
investigate various biodiesel influences on performance and emissions [5, 7, 57]. The
authors couldn’t find any publications relating to low-speed diesel engines tested using
a bio-based alternative to HFO for measuring engine performance and emissions.
This review aims to compare the relative engine performance and emissions of
FAME and HTL biocrude from microalgae for high-speed and low-speed engines,
based on physicochemical properties. This requires a brief description of the
conversion technologies to set the context.
3.2 MICROALGAE BIOMASS TO BIOFUEL CONVERSION
TECHNOLOGIES
Microalgae to biofuel conversion technologies can be divided into two main
processes: biochemical and thermochemical. Thermochemical processes can be
subdivided into gasification, pyrolysis and liquefaction [58]. The microalgae biomass
energy conversion technique is shown in Figure 3.1. However, microalgae biomass
has high water content (80–90%) meaning that not all conversion processes are
suitable [59]. This article focusses on technologies suitable for diesel engines.
Chapter 3: Literature review on diesel engine performance using microalgae FAME and the prospects of HTL
biocrude 39
Biochemical
conversion
Thermochemical
conversion
Fermentation Transesterification Gasification Pyrolysis
Raw microalgae
Dry
microalgae
Solvent-
extraction
Wet
microalgae
Hydrothermal
liquefaction
Thermochemical
conversion
Figure 3.1: Classification microalgae conversion processes [60].
3.2.1 Solvent extraction and transesterification to produce FAME
Solvent extraction of lipids from microalgae biomass transfers crude lipids from
a liquid phase to a second, immiscible phase. Possible solvents include benzene,
ethanol, hexane or ethanol-hexane mixtures [35, 60, 61]. The most widely used solvent
is hexane, due to its lower cost, ready availability, low toxicity, density and boiling
point [62, 63]. Extracted lipids are dissolved in the solvent and form a solution separate
to the cell debris and hydrophilic compounds [64, 65]. This is due to oil being highly
soluble in the organic solvents used in this process, which is shown in Figure 3.2. Non-
polar solvents typically are better at extracting non-polar lipids whereas polar materials
are typically extracted better by polar solvents. Therefore, a solvent with similar
polarity to that of the crude lipids being extracted is desirable. This connection between
polar compounds minimises the co-extraction of non-lipid contaminants (protein and
carbohydrates) [66]. Higher lipid yields can be achieved by either disrupting cell walls
before adding the solvent or using a combination of solvents such as hexane (non-
polar), methanol (polar) and water [62]. Contamination is a major obstacle when using
organic solvents, as pigments can be extracted into the product.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 40
Dry biomass
Extraction vessel
(Solvent extraction)
Filtration
Distillation
of solvent
Raw oil
Biofuel
Transesterification
Figure 3.2: Solvent-extraction and transesterification SET process.
The extracted lipid is then converted into biodiesel via transesterification.
Transesterification is a chemical reaction between triglycerides and alcohol in the
presence of a catalyst (usually basic) to produce biofuel [67]. FAME can be used
directly in a conventional high-speed CI (i.e. diesel) engine.
3.2.2 HTL to produce microalgae biocrude
HTL is a thermal depolymerisation method to convert wet biomass into biocrude
at elevated temperature and pressure [68, 69]. HTL has been effectively carried out at
both sub-critical and super-critical conditions but the problem for high-speed diesel
engines is that the chemical composition and physical properties of HTL biocrude are
not similar to that of diesel and biodiesel [47, 70, 71]. HTL produces biocrude with
higher oxygen and nitrogen content compared to diesel. In addition, HTL biocrude
contains inorganic salts and metals, which pose challenges with traditional refining
process [32, 55, 72]. Therefore, the biocrude requires further processing (i.e.
upgrading) to improve quality by reducing the levels of these undesired components.
The retention times in the reactor are usually in the range 5–120 min. Figure 3.3 shows
the HTL conversion process using dichloromethane (DCM) as the solvent.
Chapter 3: Literature review on diesel engine performance using microalgae FAME and the prospects of HTL
biocrude 41
As mentioned, liquefaction can occur with high moisture content feedstocks [59,
60]. However, this can result in high energy costs. The formulation of additives could
help to improve process economics [60].
HTL process
Residues
Liquid phase
DCM phaseAqueous
phase
Bio-crude
Filtration
Evaporation
Extraction
Wet biomass
Figure 3.3: HTL process and product separation [33].
3.2.3 Comparison of biomass to biocrude conversion technology
The main benefits of liquefaction are that many different products can be
produced and that drying of the biomass is not required. Solvent-extraction-processed
biofuel contains only FAME and is produced from dry biomass. HTL biocrude doesn’t
depend on the lipid content of the feedstock because the whole biomass is converted
into biocrude and so conversion yields are high. Conversely, solvent-extracted biofuel
depends on the lipid content of the biomass. Solvent extraction is a low-pressure
process but high-cost solvent is required, whereas HTL is a high-pressure process that
produces a much broader range of chemicals and requires further refining to produce
suitable physicochemical properties for high-speed diesel engines. For low-speed
diesel engine application, HTL biocrude is closer to HFO with considerably lower
sulphur content and so relatively less refining is required.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 42
There have been several studies investigating the price of microalgae biodiesel
with prices from studies found to be in the range of $0.63/L (best-case scenario with
highly optimistic lipid yields) [21] to $2.60/L [19]. $1.50/L was found for a multi-
output system including fertiliser co-production [22]. In contrast, there have been very
few techno-economic investigations exploring the cost of microalgae HTL biocrude
production.
The physicochemical properties of biofuels are important parameters with
respect to the quality of fuels and their application. The physical properties vary with
chemical composition including the carbon-chain length and the degree of
saturation/unsaturation [7, 38, 43, 73]. Other factors that affect fuel suitability for a
conventional engine include chemical composition, molecular structure, cetane
number (CN), acid value and sulphur content. Moreover, these fuel properties affect the
engine performance and exhaust emission results [57]. Several studies have shown that
fuel properties can significantly affect engine exhaust emissions [57, 73-80]. There is
widespread agreement that no single factor is responsible for biodiesel engine
performance and the character of exhaust emissions. Table 3.1 shows the influence of
fuel properties on heavy-duty diesel engine exhaust emissions.
Table 3.1: Influence of fuel properties on heavy-duty diesel emissions [57, 81, 82].
Fuel properties influence HC CO NOx PM
Reduce density ↑↑ ↑ ↓ ↓↓
Increase CN ↓↓ ↓↓ ↓ 0
Increase oxygenate * ↑ -- 0 ↓
Reduce sulphur 0 0 0 ↓↓
Legend: ↑↑, ↓↓- large effect, ↑, ↓-small effect
* - Tentative results, require confirmation by further work
HC: Hydrocarbon , CO: Carbon monoxide, NOx: Nitrogen oxide,
PM: Particulate matter
McCormick et al. [83] concluded that the molecular structure of biofuel has a
direct relationship with emissions. The effect of biofuels on high-speed diesel engine
emissions has been investigated by Song et al. [84], who found reduced emissions
compared to diesel. CN is measured based on the ignition and combustion quality of
Chapter 3: Literature review on diesel engine performance using microalgae FAME and the prospects of HTL
biocrude 43
the fuels. Higher CN fuels tend to increase power output and reduce emissions. The
density of biofuel is generally higher than for conventional diesel fuel. The viscosity
and surface tension of the fuels act to reduce atomisation. Additionally, the raw
material greatly influences their physicochemical properties.
3.2.4 FAME biofuel properties
The purified biofuel obtained from microalgae oil transesterification (i.e.
FAME) has been tested for physicochemical properties by several researchers [3].
Table 3.2 shows some of the chemical and physical properties of microalgae biofuel,
standard biodiesel and diesel properties; many properties are similar. The CN of
FAME microalgae biofuel is close to ASTM D6751-12 diesel. Lower CN affects
ignition delay and can reduce engine performance. The kinematic viscosity and density
of the microalgae biofuel is higher than standard biodiesel and diesel fuel, which can
affect atomisation, penetration and ignition in the combustion chamber. Basically,
those properties reduce engine performance. Islam et al. [3] experimentally
investigated common-rail heavy-duty high-speed diesel engine performance with
microalgae FAME. They found brake-specific fuel consumption (BSFC) for
microalgae FAME was higher compared to diesel and brake thermal efficiency (BTE)
was lower than diesel [3]. Due to higher fuel density, BSFC is higher for microalgae
biofuel and BTE is lower due to its lower calorific value [3]. However, the chemical
composition and structure of microalgae biofuel is different compared to that of diesel
fuel. Microalgae biofuel contains compounds with higher carbon-chain length than
diesel. A key difference between microalgae FAME and diesel is the presence of
oxygen. The chemical properties affect the combustion inside the engine cylinder and
reduce exhaust emission from microalgae biofuel [3, 85-87].
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 44
Table 3.2: Solvent-extraction microalgae biofuel properties [3, 86, 87].
Fuel Properties Unit
Standard Biodiesel [82]
Petroleum
Diesel ASTM
D6751-12
EN 142
14:2012
Microalgae
FAME [3]
CN 47 51 46.5 50–53.3
Kinematic
viscosity@40 ˚C mm2/s 1.9–6.0 3.5–5.0 5.06 2.62–2.64
Density @15 ˚C kg/L -- 0.86–.90 0.912 0.82–0.84
HHV MJ/kg -- -- 39.86
LHV MJ/kg -- -- 37.42 44
Acid value mg KOH/g 0.50 0.5 max 0.14 0
Flash point (close
cup) ˚C 93 101 95 71
Sulphur content mg/kg 15 ppm 10 max 7.5 5.9
Cloud point ˚C Report Report 16.1 4
Lubricity @60 ˚C mm -- 1 max 0.136 0.406
Oxygen content wt.% -- -- 10.47 0
Hydrogen content wt.% -- -- 11.12 13.86
Carbon content wt.% -- -- 78.41 86.13
Nitrogen content wt.% -- -- 0 0
3.2.5 HTL biocrude properties
HTL biocrude produced from various kinds of biomass including microalgae is
a dark, highly viscous and energy-dense liquid [23, 50, 88]. Its energy content is 70–
95% of that for diesel fuels and is similar to HFO [54, 89]. Typical chemical
components are carbon, hydrogen, oxygen and nitrogen. The nitrogen content is a key
difference to other biofuels. The biocrude contains a carbon content of usually 70–
75%, an oxygen content of 10–16% and 3–7% nitrogen, as shown in Table 3.3. The
oxygen contents of microalgae biocrude is significantly lower than the oxygen content
in the original microalgae cells. The biocrude components change with respect to
experimental condition and biomass feedstocks [51, 89].
The physicochemical properties of biocrude are strongly dependent on biomass
feedstock and conversion technology. It is a mixture of compounds including
aromatics, oxygenated and nitrogenised species, straight carbon chains of varied
molecular weights [90]. The biocrude’s chemical components are affected by the
processing conditions including temperature, pressure and sample-slurry
concentration. A major problem related to HTL biocrude is its high N content, usually
Chapter 3: Literature review on diesel engine performance using microalgae FAME and the prospects of HTL
biocrude 45
in the vicinity of 3–7%, which can lead to high NOx emissions upon combustion [51,
67]. The calorific value of the biocrude is lower compared to diesel because the oxygen
content and the carbon-to-hydrogen ratio of biocrude are lower. The calculated
calorific value based on chemical composition using the Dulong formula [91] is shown
in Table 3.3 for different microalgae biocrude. However, the chemical and physical
properties of microalgae biocrude differ significantly compared to FAME microalgae
biofuel.
Table 3.3: Elemental analysis and HHV of microalgae HTL biocrude.
HTL biocrude
(on dry basis)
Operating
conditions Fuel Properties
Refe-
rence Temp.
(°C)
Time
(min)
Chemical composition
(wt. %) HHV
(MJ/kg) C H N O
Scenedesmus sp. 350 60 75.6 10.1 3.97 10.3 37.4 [92]
Enteromorpha
prolifera 370 40 77.9 9.6 5.6 6.9 39.4 [51]
Enteromorpha
prolifera 300 30 64.5 7.7 5.4 22.4 30.8 [50]
Sargassum
patens C. Agardh 340 10 64.6 7.4 2.5 25.5 30.4 [93]
Laminaria
saccharina 350 15 82.0 7.1 4.9 6.0 37.4 [72]
Saccharina sp. 340 87 79.4 8.0 4.1 8.5 37.5 [53]
Chlorella
pyrenoidosa 350 60 75.1 9.9 7.3 7.7 38.1 [94]
Lemna sp. 350 30 72.1 7.8 4.6 15.5 32.8 [95]
3.2.6 FAME and HTL biofuel properties
The FAME microalgae biodiesel is a deep-brown low-viscosity fuel, whereas
microalgae HTL biocrude is dark high-viscosity oil. The chemical composition,
compound structure and carbon-chain length differ significantly. Islam et al. [3]
performed a detailed investigation with FAME microalgae biodiesel as shown in Table
3.4. The chemical composition was found to be similar to standard biodiesel. In
contrast, the properties of microalgae HTL biocrude are similar to HFO, which as
shown in Table 3.6. FAME microalgae biodiesel is suitable for high-speed diesel
engines including buses, tractors, cars and similar vehicles while HTL biocrude is
suitable for low-speed diesel engines, such as large marine ship engines and large
electric generators.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 46
Table 3.4: FAME versus HTL microalgae biofuel properties in comparison with
conventional diesel and HFO.
Fuel Properties Unit
Microalgae
(FAME)
[3]
Diesel
[3, 96]
Microalgae
(HTL)
[92]
HFO
(selected)
[97]
Viscosity@40 ˚C mm2/s 5.06 2.64 70.7–73.8 743.4
Density @15 ˚C kg/L 0.912 0.84 0.97–1.04 0.99
HHV MJ/kg 39.86 44 30–35 ---
Sulphur content mg/kg 7.5 5.9 0 2030
Oxygen content wt% 10.47 0 10.33 1.64
Hydrogen content wt% 11.12 13.4 10.14 9.63
Carbon content wt% 78.41 86.5 75.56 85.87
Nitrogen content wt% 0 0 3.97 0.46
3.3 ENGINE PERFORMANCE AND EMISSIONS
HTL biocrude could be used in low-speed diesel engines, which will result in a
significant change to exhaust emissions. The engine performance and exhaust
emissions results should be different to microalgae FAME and existing biofuels [3,
98]. So, one of the options is to use HTL biocrude in low-speed diesel engines with
little or no modification. To achieve an efficient biofuel that produces less emissions
and more power without hindering engine operation, the physicochemical properties
must be optimised.
Diesel engine performance parameters for both high-speed and low-speed
engines include engine power, torque, BSFC and BTE [3, 5, 99]. It is commonly
argued that biodiesel slightly reduces the power output and torque compared to diesel
due to its lower calorific value [3, 57, 73, 100]. Utlu and Kocak [101] found around
4.5% and 4.3% reductions in power and torque, respectively when used waste cooking
oil methyl ester, compared to diesel. Hansen et al. [102] found that lower calorific
value is not the only factor that reduces the power and torque, but density and viscosity
also have significant effects on engine output power and torque. For example, higher
viscosity and density of biofuels causes an increased amount of fuel injected into the
combustion chamber, which can lead to an increase in power [103]. Conversely, lower
atomisation due to higher viscosity can sometimes reduce combustibility of the fuel
and reduce power [103, 104]. Furthermore, higher lubricity of biodiesel will reduce
the frictional loss and consequently recover engine power and torque [105].
Chapter 3: Literature review on diesel engine performance using microalgae FAME and the prospects of HTL
biocrude 47
Researchers found no noticeable difference for 5% rapeseed biodiesel blend usage
results in terms of power and torque, compared to diesel [106, 107]. It is also reported
that the BSFC of biofuel is increased, compared to diesel [107]. In a high-speed diesel
engine running with rapeseed oil and its blends, Buyukkaya [106] found that BSFC
increased by up to 11%, compared to diesel. In summary, it was proposed that power
and torque were not only dependent on feedstock and fuel properties, but also on the
engine type and operating conditions, such as engine speed, load, injection timing and
injection pressure [104, 108].
Diesel engine emissions contain pollutants that adversely affect human health
and the environment. Diesel engine emission regulations have included NOx, PM and
CO since the adoption of the first emission standards. More recent regulations also
introduced emission limits on CO2 and other greenhouse gases. The use of renewable
biofuel plays a role in energy security issues by reducing dependence on imported
petroleum products, which are being depleted rapidly [109, 110]. Despite this, other
factors are having an influence on the uptake of biofuel, such as the need to mitigate
global warming and to reduce exhaust emissions [85, 111].
3.3.1 Microalgae FAME
Low-speed diesel engines are finding an increasing market for marine
applications and large scale electric power generation due to their high combustion
efficiency. Unfortunately, diesel engine exhaust emissions are increasing with
economic growth and causing widespread concern in terms of environmental pollution
[3, 96, 112-114]. However, diesel engine performance with FAME microalgae has
been investigated by only a small number of researchers [3, 86, 87]. Their results differ
due to the difference in engine operating conditions and the variation in fuel properties
[3, 86]. High viscosity and low volatilities of microalgae FAME is one of the main
reasons for diesel engine tests over long-periods. Higher viscosities of microalgae
biofuel affects fuel droplet size, resulting in poor atomisation and fuel penetration in
the cylinder, which is very important for combustion, but it reduces emissions relating
to the oxygen content in the biofuels [5, 29, 115]. The influence of microalgae
biodiesel (FAME) on exhaust emission (only gases) is shown in Table 3.5.
Hydrocarbon (HC) and CO are consistently lower compared to diesel when using
microalgae biodiesel as shown in Table 3.5. Conversely, nitrogen oxide emissions
showed no consistent trend.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 48
Table 3.5: Influence of microalgae biodiesel (FAME) on exhaust emissions [116].
University FAME blend HC CO NOx References
Queensland University of
Technology, Australia
10%MBD+90%D
20%MBD+80%D
50%MBD+50%D
↓ ↑ [3]
Aleksandras Stulginskis
University, Lithuania 30%MBD+70%D ↓ ↓ ↑ [117]
Çukurova University,
Turkey
5%MBD+95%D
10%MBD+90%D
25%MBD+75%D
50%MBD+50%D
↓ ↓ [87]
Colorado State University,
USA
20%MBD+80%D ↓ ↓ ↑ [118]
Utah State University, USA 100MBD ↓ ↓ ↓ [34]
Legend: ↑- increase, ↓- decrease, ↓↑- near equal. MBD= Microalgae, D+ Diesel
Tuccar et al. [86] conducted emission and engine performance tests using a four-
cylinder diesel engine with microalgae biofuel blends. The average torque value of the
engine reduced approximately 2.7% for D80B20 blend compared to that of diesel fuel.
The oxygen content of microalgae biofuel led to a decrease in the brake torque and
brake power when compared to diesel fuel [86]. The highest BSFC values increased
by 10.9% for D80B20 compared to diesel fuel. Conversely, the CO, particulate matter
(PM), and HC emissions were lower for microalgae biofuel blends [86, 87]. Islam et
al. [3] investigated microalgae biofuel exhaust emission and engine performance in a
common rail four-cylinder diesel engine. The BTE decreased for different microalgae
biodiesel (FAME) blends compared to diesel fuel and BSFC increased but exhaust
emissions improved [3]. However, due to the high flash point, density and lubricity,
the combustion efficiency reduced but emissions improved because of the oxygen
content in the microalgae biofuel.
3.3.2 HTL Microalgae biocrude
An extensive literature review by the authors did not find any literature relating
to diesel engine performance and exhaust emission measurements using microalgae
HTL biocrude. Due to the physicochemical properties of the HTL biocrude it is not
Chapter 3: Literature review on diesel engine performance using microalgae FAME and the prospects of HTL
biocrude 49
possible to use it in a conventional high-speed diesel engine without first upgrading.
However, the HTL biocrude could be used in heavy duty marine diesel ship engines
(low-speed diesel engine). Marine ship engines generally use HFO, which has several
common properties to HTL biocrude [54, 71, 119, 120]. HFO produces high levels of
emissions due to physicochemical properties of the HFO in particular high kinematic
viscosity and sulphur (shown in Table 3.6). It is also noted that while researchers
generally have better access to on-road vehicle emission information, it is not easy to
access ship engines for testing performance of biofuels and their emissions [97].
Almost 80% of marine engines worldwide are dominated by just a few companies such
as MAN, BMW, Wartsila and Mitsubishi. These companies have very few engine
dynamometers and scientists are rarely granted access to such extraordinary facilities
[97, 121]. So, it is quite difficult to explore the exact emissions from marine diesel
engines. However, HTL microalgae biocrude seems to be a suitable substitute to HFO
based on their properties (as shown in Table 3.6). There are vast applications of HFO,
such as marine diesel engines, steam boilers, and power plants. Exhaust emissions are
much higher compared to diesel fuel due to their chemical composition [97]. On the
other hand, HTL biocrude could be a viable alternative to HFO. It would be a great
achievement in terms of emission reduction because HTL biocrude comes from
renewable sources. Microalgae HTL biocrude could be a good alternative fuel for
marine diesel engines, which would reduce exhaust emission substantially.
HFO can’t be used in high-speed diesel engines due to its fuel properties. The
properties of diesel/biodiesel and HFO are fundamentally different, including density,
viscosity, and HHV. However, Rahman et al. [27] and Pham et al. [30] experimentally
investigated the effect of the physicochemical properties of biodiesel on high-speed
diesel engine exhaust emissions. Exhaust emissions from diesel engine vehicles and
power plants contain a high concentration of nano-sized particles and gaseous
pollutants [19, 31, 32]. Fine particles are present in heavy-duty diesel engine exhausts,
which can cause cancer and other diseases due to their small size [27]. Alternative
fuels, such as those from microalgae, are another one of the potential options for
reducing emissions [33-37]. Also, using biodiesel in diesel engines has the potential to
greatly reduce carbon emissions and is a renewable source of energy. Many groups
have investigated novel uses of conventional biofuels in diesel engines to investigate
engine performance and exhaust emissions [3, 29, 38]. Alternative drop-in fuels for
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 50
transportation provide an excellent opportunity for reducing greenhouse gas (GHG)
emissions as they can be incorporated into existing fuel-distribution networks with
minimal engine modification. This will support energy security and environmental
sustainability. Second- and third-generation biofuel must be actively developed
because they come from biomass, which do not affect the food chain. Microalgae
biomass presents the advantages of rapid growth, high oil yield per unit area, and being
cultivated on land unsuitable for other forms of cultivation [39].
Table 3.6: Qualitative comparison between microalgae HTL biocrude and HFO.
Fuel Properties Diesel
Microalgae
HTL
biocrude
HFO
Similarity between
HTL & HFO
Density Low High High Similar
HHV High Medium Medium Similar
Appearance Yellow Black Black Similar
Viscosity Low Medium High Moderately similar
Hydrogen content High Low Low Similar
Carbon content High Low Medium Moderately similar
Nitrogen content No High Medium Not similar
Sulphur content Low No High Not similar
Ash content Low Low High Not similar
Asphaltene content Low Low High Not similar
Heavy duty marine diesel engine exhaust emissions contribute significantly to
the total exhaust emissions from the transport sector globally. In addition, shipping
offers a lower GHG option for the transport of goods [122]. Almost two-thirds of all
heavy marine engines are operated with HFO [119]. The heavy-duty marine diesel
engine uses HFO as a primary fuel, which usually contains high amounts of sulphur
compounds. The relatively high amount of sulphur in HFO is approximately ten times
higher than that of light fuel oil (LFO), which generally produces sulphuric acid with
other exhaust emissions [112]. It is crucial nowadays for shipping companies to reduce
bunker consumption while maintaining a certain level of shipping service in view of
the high bunker price and concern about shipping emissions [123, 124]. The emissions
are different due to the fact that the vessel types and measurement methods are
different. However, most of the vessels use HFO/marine fuel oil (MFO)/residue; none
use renewable HTL biocrudes. Therefore, this HTL biocrude could be an alternative
for marine engines.
Chapter 3: Literature review on diesel engine performance using microalgae FAME and the prospects of HTL
biocrude 51
Table 3.7 shows emissions for various types of ocean-going vessels. The
emissions are different due to the fact that the vessel types and measurement methods
are different. However, most of the vessels use HFO/marine fuel oil (MFO)/residue;
none use renewable HTL biocrudes. Therefore, this HTL biocrude could be an
alternative for marine engines.
Table 3.7: Exhaust emissions for different ocean-going vessel using
HFO/MFO/residual.
Vessel
type
Measurement
type
g NOx/kg
fuel
g SO2/kg
fuel
Type of fuels Reference
HFO/MFO HTL
Various Remote 72 ± 24 30 ±15 HFO
Res
earc
h g
aps
[125]
Container Onboard 85.9 ± 0.5 50.3b HFO [126]
Freight Remote 87.0 ± 29.6 20.4 ±5.6 HFO [127]
Container Remote/
Onboard
59.8 ± 20.8 30.4 ±16.6 HFO [127]
Crude
tankers
79.2 ± 23.4 27.3 ±17.4 HFO [128]
Container Onboard 90.5a 41.6b HFO [129]
Ship Remote
(airplane)
43 ± 26 23 ± 7 MFO [130]
Container Remote
(airplane)
65.5 ± 3.3 52.2 ± 3.7 Residual [131]
However, environmental legislation regarding exhaust emissions and a high
dependency on fossil fuels set the scene for a growing area of research concerning
alternative fuels and their effect on engine performance and emissions [43]. Similar to
HFO, the HTL biocrude is also receiving much attention in recent years due to high
yields and its ability to utilise wet biomass [47]. With the HTL method, biomass is
changed into gas, liquid and solids such as common pyrolysis in the gas phase [48].
The HTL biocrude could be an alternative of HFO, which is used for marine engine
operation. It will help to reduce exhaust emissions for heavy duty diesel marine
engines and will improve engine performance for HTL biocrude.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 52
3.4 CONCLUSION
Microalgae-based biofuels have potential for replacing fossil fuels in both high-
speed and low-speed diesel engines. Microalgae HTL biocrude could be used in low-
speed diesel engines including marine diesel engines and large power generators
without further treatment due to their properties, which are similar to HFO. This could
mean that microalgae HTL biocrude could be a future fuel of marine diesel engines.
However, the chemical composition including sulphur, nitrogen and oxygen content
of HTL are different, which both affect engine performance and exhaust emissions.
HTL biocrude would reduce exhaust emissions for low-speed marine diesel engines
compared to HFO, especially soot emissions due to their very low sulphur content,
although NOx emissions may increase. Furthermore, HTL may reduce the engine
performance in terms of output power compared to HFO due to their higher oxygen
content and lower HHV. Conversely, solvent-extraction and transesterification to
produce microalgae FAME is better suited to high-speed diesel engines, such as heavy
vehicles, as a substitute for diesel. The physicochemical properties of FAME
microalgae and diesel are similar except for the higher oxygen content in FAME.
Therefore, microalgae FAME results in high-speed diesel engines having decreased
emissions but there is a small penalty in terms of engine power compared to diesel
fuel. Both, microalgae FAME and HTL, types of fuel could be used to reduce exhaust
emissions and also replace fossil fuel in the future although further improvements
could be made with more research.
3.5 ACKNOWLEDGEMENTS
This research was supported by the Australian Research Council’s Linkage
Projects funding scheme (project number LP110200158). The author would like to
acknowledge Dr. Mohammad Aminul Islam for assistance with reviewing this
manuscript.
Chapter 4: Literature review on thermochemical conversion of waste tyres 53
Chapter 4: Literature review on
thermochemical conversion
of waste tyres
Abstract:
The growing demand of transport and the development of industrialised
countries increases the production of tyres every year. ELTs are a significant
environmental hazard; the mass that is generated each year is around 17 million tons.
It has been found that a thermochemical conversion process can convert whole tyres
into oil, which has similar characteristics to diesel and gasoline. The Australian Bureau
of Resource and Energy Economics has reported that petroleum consumption in
Australia has reached about 64 billion litres per annum with nearly 70% used for
the transport sector in 2013. Diesel fuel holds the largest share, which is 41%. It is
estimated that around 1% of diesel fuel could be replaced by waste-tyre oil in
Australia. This review summarises two recent conversions of waste tyre to oil and the
application of that fuel in diesel engines. The first step was to develop a process to
convert waste tyres to tyre oil, which could be used in a diesel engine directly or as a
blended fuel. The second step was to analyse and measure its performance and
emissions in diesel engines to determine the viability of using oil from waste tyres as
fuel, since it has less impact on the environment and retains the same performance in
the vehicles. In addition, the thermochemical conversion of waste tyres produces steel
and carbon/char, which could be used in the re-rolling and cement manufacturing
industries respectively.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 54
4.1 INTRODUCTION
The rapid global spread of industrialisation has led to an increase in the
production of vehicles as a primary means of transport to mobilise citizens and grow
economies. Very large numbers of waste tyres are generated every year [12, 13, 132,
133]. The number of tyres produced worldwide is approximately 1.5 billion per year,
which means the same number are ending up as wasted tyres. This is the equivalent of
about 17 million tons [26, 134, 135]. Most of the waste tyres are stored for disposal,
which represents an environmental problem because the life of a tyre is so long.
Recycling waste tyres is extremely difficult because of their highly complex structure,
the diverse composition of the raw material, and the chemical structure of the rubber
from which the tyres are manufactured. The process of manufacturing rubber products
is based primarily on the irreversible vulcanisation reaction that takes place between
natural and synthetic diene rubbers, sulphur and a variety of auxiliary compounds.
Therefore, transverse bonds connect the elastomer chains to and from the cross-linked
structure of the rubber. As a result, rubber is characterised by elasticity, insolubility
and infusibility, which do not permit being easily reprocessed. Their recycling requires
much time and energy and is based mostly on mechanical, thermochemical destruction
[136]. A tyre consists not only of rubber, which makes up some 70–80% of the tyres
mass, but also of steel belts and textile overlays, which give the tyre its ultimate form
and utilitarian properties, which are shown in Table 4.1.
For the last decade, the management of waste tyres has been regulated by
organisations such as the Waste Management Association of Australia (WMAA),
which controls the final destination of waste tyres [137]. There are many ways to
recycle used tyres. The most common uses for waste tyre recycling are: waste tyre to
oil, rethreading, energy recovery, product recycling and material recycling.
The most common method used to process ELTs into fuel is pyrolysis, which is
a form of thermochemical conversion. Pyrolysis is the thermal degradation of the
organic component of tyres at a high temperature to produce oil, gas and char and
recovery steel [13]. The oil obtained from this process can be used directly in
industrial application and in diesel engines or further up graded. The most important
characteristic of this oil is the low exhaust emission in comparison with petroleum-
derived fuel oils. There is a large amount of research covering diesel engine
performance and emissions using tyre pyrolysis oil [24, 26, 138, 139].
Chapter 4: Literature review on thermochemical conversion of waste tyres 55
Table 4.1: Major components of tyres [135, 137, 140, 141].
Components of
tyre
Average
composition
of tyre
Composition of tyre
in USA
Composition of tyre
in European Union
Passenger Truck Passenger Truck
Total rubber 45–47 -- -- -- --
Natural rubber -- 14 27 22 30
Synthetic rubber -- 27 14 23 15
Carbon black 21.5–22 28 28 28 20
Steel 16.5–25 14–15 14–15 13 25
Textile 5.5 16–17 16–17 14 10
Average
weight
New -- 11 54 8.5 65
Old -- 9 45 7 56
4.2 WASTE TYRE TO OIL USING THERMOCHEMICAL CONVERSION
Thermochemical conversion methods conducted at high temperatures, with or
without the presence of oxygen, chemically degrade waste tyres. Pyrolysis, thermal
cracking and gasification conversion methods are used to produce fuel [68, 69, 142,
143]. Among different possible solutions, one potential resolution to the issue of tyre-
waste settlement is to transform them to fuels along with other related hydrocarbon
(HC)-based products using thermochemical processes [144].
4.2.1 Waste conversion using pyrolysis
The pyrolysis process, among other similar thermochemical processes, is
assumed to be most friendly to the environment due to the fewer processing steps
involved [144]. The process involves the decomposition of the solid at a considerably
inflated temperature of around 300 °C to 900 °C in an environment that is free of
oxygen and resultantly producing char, oil and gas [68, 145-148]. The crucial
conditions in the experiments that have impact include the degree of temperature and
the rate of heating. Based on these factors, the resulting oil and energy yield is
determined and are assessed in the diesel engine for evaluation in respect to
performance and emissions. Research has also revealed that inflated temperatures
along with increased gas residence in the heated areas of the reactor can have a
negative influence on the fuel and the conversion of oil to gas. Varying yield outcomes
due to the pyrolysis process are dependent upon different conditions and reactor
settings [146, 149].
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 56
Many technologies have been developed for the generation of ethanol, char,
biodiesel etc. using the pyrolysis process. Temperature is the main factor to control the
configuration of the pyrolysis process. There are three main kinds of pyrolysis: (i) slow
pyrolysis process, (ii) fast pyrolysis process, and (iii) flash pyrolysis process. The
pyrolysis processes depend on factors such as temperature, material size, period etc.
[68, 150]
There is a different type of pyrolysis reactor used to produce waste tyre to oil,
char and gas. The pyrolysis process using various temperature ranges depend on
reactor types and product yield. The reactor is the same but product yield is different
due to the operating conditions. Table 4.2 shows a range of pyrolysis reactors and their
product yield for waste tyres.
Chapter 4: Literature review on thermochemical conversion of waste tyres 57
Table 4.2 Collection of pyrolysis reactors and product yield from the pyrolysis
of waste tyres.
Reactor
Experimental
Condition
Maximum oil yield Refer-
ences
Temp
C
Oil
wt.%
Char
wt.%
Gas
wt.%
Fixed bed
batch
400–700C Temp. 500 40.26 47.88 11.86 [132]
Closed batch
reactor
350–450C Temp.
30 min-1 heating
rate
450 ~63 ~30 ~7 [151]
Fixed bed,
batch
350–600C Temp
5C min-1 and 35
min-1 heating rate.
400 38.8 34.0 27.2 [152]
Fixed bed,
batch, internal
fire tubes
375–575C Temp:
750g tyre
475 55 36 9 [153]
Moving screw
bed
600–800C Temp.
3,5–8.0kgh-1 mass
flow rate
600 48.4 39.9 11.7 [154]
Two stages
fixed bed
reactor
600–800C Temp
2 ml h-1 flow rate
600 5.03 39 81.1 [155]
Two stages
fixed bed
reactor
600–800C Temp
5 ml h-1 flow rate
600 10 38 82 [155]
Two stages
fixed bed
reactor
600–800C Temp
Not water
600 22
37 27.2 [155]
Quartz
microwave
oven reactor
Flow rate nitrogen
1L-0,4L m-1
450Watts
450–650C
- 43 45 12 [156]
Rotary reactor 600–1000C ratio
0.2. Using waste
heat of blast-
furnace slag.
600 30.21 62.67 7.12 [157]
Rotary reactor 600–1000C ratio
0.6. Using waste
heat of blast-
furnace slag.
1000 55.8 33.67 10.50 [157]
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 58
4.2.2 Thermal cracking of waste tyre
Thermal cracking is a recent thermal conversion for waste tyres. The pyrolysis
process transfers the colloidal particles to the pyrolysis furnace for pyrolysis, and the
colloidal particles are then subjected to thermal cracking at high temperature and high
pressure. Colloidal particles refer to substances of a minor size that are floating in a
medium of one of three substances: a solid, a liquid, or a gas. Colloidal particles are
heterogeneous in medium. The gas-phase product enters the washing tower to
condense and cool, and the condensed fuel oil is stored in the cooling tank. Non-
condensable HC gas phase is recovered as a gas, from the pyrolysis furnace [158].
Figure 4.1 shows the thermal cracking process for waste tyre to fuels.
Waste tyre
1. whole
2. Commuted
Thermal Cracking
1. Temperature (350 C – 1000 C)
2. Absence of oxygen
3. Fixed bed batch
4.Close batch
5.Rotary reactor
CondenserChar
(40 – 50) wt. %
Steel wire
(15-20) wt. %
Tyre Oil
(40 – 60) wt.%
Figure 4.1: Thermal cracking of waste tyre [158].
4.3 WASTE TYRE TO OIL, CARBON AND STEEL
Recycling of waste tyres into useful products is of interest for both
environmental and economic reasons. Many researchers have been working to solve
the above issues and convert waste tyres into valuable products including oil, carbon
and steel. Waste-tyre oil could be used by industry for heating purposes, further refined
for use in diesel engines or used directly as blended fuel in some stationary diesel
engines. Carbon has a plethora of industrial uses, from toothpaste to electrodes and
pharmaceutical goods, as well as being about 35% cleaner than coal and burning
hotter, while steel can be sold as scrap metal or returned to tyre manufacturers for
reuse.
Chapter 4: Literature review on thermochemical conversion of waste tyres 59
4.3.1 Oil from waste tyres
Oil from waste tyres using a thermochemical conversion process is varied due
to the conversion process and the operating conditions. The tyre oil colour is black and
it also has a recognisable odour. Table 4.3 shows the physicochemical properties of
fuel. Those properties identify the fuel category and quality. In Table 4.3, two different
types of tyre oil are presented: one that is produced using pyrolysis and the other that
is produced by a destructive distillation process invented by GDT. Pyrolysis oil density
is higher than that of biodiesel, diesel and GDT-tyre oil. However, GDT-tyre oil
properties are similar to diesel, therefore making it suitable to be used in a diesel engine
directly. Tyre pyrolysis oil is not suitable.
Table 4.3: Physicochemical properties of tyre oil, WCBD and diesel.
Properties Units Diesel Biodiesel
(WCBD)
TPO DGT_
TO
References
Density Kg/L 0.83 0.88 0.91–.96 0.84 [3, 12, 24]
HHV MJ/L 45.6 37.2 38–42 42.3 [3, 12, 24]
Water content mg/kg <30 -- 118 [12, 24]
Aromatic % m/m 26.0 -- 39.3 21.4 [12, 24, 159]
Kinematic V. mm2/s 2.66 4.73 3.22–6.3 3.43 [3, 12, 24]
Carbon © Wt. % 87.0 76.9 79.61–88 [3, 12, 24, 133]
Hydrogen (H) Wt. % 13.0 12.2 9.4–11.73 [3, 12, 24, 133]
Nitrogen (N) Wt. % -- -- 0.40–1.05 [3, 12, 24, 133]
Oxygen (O) Wt. % 0 10.9 0.5–4.62 [3, 12, 24, 160]
Ash content Wt. % 0.01 .002–0.31 10* [12, 160]
Flash point ° C 50 130 20–65 97 [12, 160]
Cetane index 53.2 58.6 28.6 51.7 [3, 24]
*ppm
4.3.2 Char from waste tyres
The chars from waste-tyre pyrolysis are another valuable product. It is reported
that the char produced from tyre conversion ranges from 22–49% by weight [12].
There are many researchers that have been investigating the characteristics of the char.
Table 4.4 shows the properties of waste tyre char. The chars have a low heating value,
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 60
29.3–31.5 MJ/kg, compared to tyre oil, which has a range of 38–42 MJ/Kg. The tyre
char can be used by different industries including cement and fertiliser.
Table 4.4: Properties of waste-tyre chars.
Properties Units Tyre pyrolysis char
[161] [162] [163] [164]
HHV MJ/kg 30.8 31.5 30.7 29.3
Water content mg/kg 0.37 2.35 3.57
Carbon (C) Wt. % 88.19 82.17 85.31 80.3
Hydrogen (H) Wt. % 0.6 2.28 1.77 1.3
Nitrogen (N) Wt. % 0.1 0.61 0.34 0.3
Sulphur (S) Wt. % 1.9 2.32 2.13 2.7
Ash content Wt. % 8.27 12.32 15.33
4.3.3 Steel from waste tyre
Waste tyres also produce steel when converted by a thermochemical process. It
is reported that the amount of steel recovered from waste tyres typically ranges from
10–15% by weight of the waste tyre [12]. The recovered steel can be reused by the
tyre manufacturer or diverted to steel re-rolling mills.
4.4 DIESEL ENGINE PERFORMANCE AND EXHAUST EMISSION
USING TYRE OIL
According to various researchers [136, 159], the resulting properties from waste-
tyre pyrolysis have similar characteristics to that of diesel and gasoline. The diesel
engine is a widely used internal combustion engine in current times. An increase in the
demand for diesel fuel and associated limited resources have resulted in a search for
alternative fuels for running diesel engines, such as alcohol, LPG, biodiesel, and CNG
[145]. The studies in the literature show differing results due to different properties of
the test fuels and different test-engine technology [165]. There are many variables to
control in an analysis on emissions in engines, for example, engine speed, fuel
composition and load condition. The fuel derived from tyres has proved to be one of
the most important and useful research outputs. However, there has been limited
funding directed at the use of tyre-derived pyrolytic fuel or diesel-blend fuel because
effects on overall engine performance as well as emissions have not been sufficiently
Chapter 4: Literature review on thermochemical conversion of waste tyres 61
confirmed. Hence, further research focusing on the emissions from diesel engines
using oil from waste tyres is expected to have a favourable impact in alternative
industries. Moreover, it could also be a promising possibility in the search to find low-
emission sources of energy.
In recent years, tests on diesel engine performance with tyre oil have been
performed by many researchers [24, 26, 138, 166]. Vihar et al. [24] experimentally
analysed the combustion characteristics of tyre pyrolysis oil in a turbo-charged six-
cylinder compression ignition engine. They found stable combustion without engine
modification as well as almost the same thermal efficiency as diesel fuel. Kapura et al.
[138] studied the effect of diethyl ether in a diesel engine run on a tyre-derived fuel-
diesel blend. They blended 40% tyre-pyrolysis oil with diesel and simultaneously 4%
diethyl ether was added to improve the CN of the blended fuel. It has been reported
that those blended fuels reduced the NO emission by approximately 25% with respect
to diesel operation at full load [138]. Cumali and Huseyin carried out an experimental
investigation of fuel production from waste tyres using a catalytic pyrolysis process
and tested it in a diesel engine. They tested several types of blended fuels in a diesel
engine including 100% tyre oil. It was reported that 50%, 75% and 100% tyre-oil
blends raise CO, HC and SO2 exhaust emissions when compared to diesel emissions.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 62
4.5 CONCLUSION
The use of waste tyres as an alternative fuel to solve the global problem of waste
tyre management, and the importance of a thermochemical process, is the focus of this
research.
Even though tyre pyrolysis oil is still a relatively new product and possibly needs more
research regarding its properties and application, it is nevertheless an innovative
solution to the problem of waste tyres.
The diesel engine experimental results on engine performance and emissions
with different tyre-oil blends were carried out using diesel as a principal fuel. In most
cases it was found to reduce exhaust emissions without any penalty to engine
performance.
Chapter 5: Experimental investigation of physical and chemical properties of microalgae biocrude using a large
batch reactor 63
Chapter 5: Experimental measurements of
physical and chemical properties
of microalgae biocrude using a
large-batch reactor
Farhad M. Hossain1,2*, Jana Kosinkova1,2, Richard J. Brown1,2, Zoran
Ristovski1,2, Ben Hankamer3, Evan Stephens3 and Thomas J. Rainey1, 2,
1 Biofuel Engine Research Facility, Queensland University of Technology (QUT), Brisbane,
Queensland 4001, Australia 2 QUT, International Laboratory for Air Quality and Health 3 University of Queensland, The Institute for Molecular Bioscience, 306 Carmody Road, St Lucia,
QLD 4072, Australia
Statement of contribution of Co-Authors for this publication
The authors listed in the table below have certified that:
1. they meet the criteria for authorship in that they have participated in the conception, execution, or
interpretation, of at least that part of the publication in their field of expertise;
2. they take public responsibility for their part of the publication, except for the responsible author who
accepts overall responsibility for the publication;
3. there are no other authors of the publication according to these criteria;
4. potential conflicts of interest have been disclosed to (a) granting bodies, (b) the editor or publisher of
journals or other publications, and (c) the head of the responsible academic unit, and
5. they agree to the use of the publication in the student’s thesis and its publication on the Australasian
Research Online database consistent with any limitations set by publisher requirements.
Title and status: Experimental investigation of physical and chemical properties of
microalgae biocrude using a large-batch reactor, (Published at Energies)
Contributor Statement of contribution
Md Farhad Hossain Candidate
Conducted the experimental work, performed data analysis, interpreted
the results wrote the manuscript and acted as the corresponding author.
Signature
Date
Jana Kosinkova Dr Jana Kosinkova graduated in Chemical Engineering from Slovak
University of Technology. Her research interests focus on the
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 64
optimisation of thermal liquefaction processing for second- and third-
generation feedstocks for the production of biocrude oils.
Conducted the experimental work in a group, performed data analysis
and helped to write the manuscript.
Richard J. Brown Principal Supervisor
Professor Richard Brown is a mechanical engineer, he is a leading expert
in thermodynamics and environmental fluid mechanics, particularly in
relation to internal combustion engine performance and emissions.
Professor Richard Brown designed and performed fuel properties related
to engine performance and reviewed the manuscript as a principal
superviser.
Zoran Ristovski Associate Supervisor
Professor Zoran Ristovski is a physicist who works at Queensland
University of Technology as one of the leading researchers on vehicle
emissions with a special focus on particulate vehicle emissions.
Professor Zoran Ristovski designed and performed fuel properties related
to engine exhaust emissions and reviewed the manuscript.
Ben Hankamer Professor Ben Hankamer is Group Leader, Chemistry and Structural
Biology Division Director, Breakthrough Science Program in Algal
Biomedicine Co-Director, Breakthrough Science program in bio-
membrane design.
Professor Ben Hankamer provided the raw microalgae for biofuel
production as a collaboration work and reviewed the manuscript.
Evan Stephens Professor Evan Stephens and the team at UQ’s Institute for Molecular
Bioscience, in collaboration with Germany’s Bielefeld University and
Karlsruhe Institute of Technology, have identified fast-growing and
hardy microscopic algae that could prove the key to cheaper and more
efficient alternative fuel production.
Professor Dr Evan Stephens provided the raw microalgae for biofuel
production as a collaboration work and reviewed the manuscript.
Thomas J. Rainey Associate Supervisor
Dr Thomas Rainey has 15 years of industrial and research experience in
biomass processing particularly in pulp and paper and sugar processing.
His research focuses on bioenergy and related value-added products.
Chapter 5: Experimental investigation of physical and chemical properties of microalgae biocrude using a large
batch reactor 65
Design concept, reviewed and edited the manuscript in the section related
to biofuel production and properties analysis.
Principal Supervisor Confirmation
I have sighted email or other correspondence from all Co-authors confirming their certifying authorship.
Professor Richard J. Brown
Name Signature Date
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 66
Abstract:
As a biofuel feedstock, microalgae have good scalability and potential to supply
a significant proportion of world energy compared to most types of biofuel feedstock.
Hydrothermal liquefaction (HTL) is well suited to wet biomass (such as microalgae)
as it greatly reduces the energy requirements associated with dewatering and drying.
This article presents experimental analyses of chemical and physical properties of
biocrude oil produced via HTL using a high-growth-rate microalga, Scenedesmus sp.,
in a large-batch reactor. The overarching goal was to investigate the suitability of
microalgae HTL biocrude produced in a large-batch reactor for direct application in
marine diesel engines. To this end we characterised the chemical and physical
properties of the biocrudes produced. The HTL literature mostly reports work using
very small-batch reactors, which are preferred by researchers, so there are few
experimental and parametric measurements for biocrude physical properties such as
viscosity and density. In the course of this study, a difference between traditional
calculated values and measured values was noted. In the parametric study, the biocrude
viscosity was significantly closer to regular diesel and biodiesel standards than
transesterified (FAME) microalgae biodiesel. Under optimised conditions, HTL
biocrude’s high density (0.97–1.04 kgL-1) and its high viscosity (70.7–73.8 mm2s-)
had enough similarity to marine heavy fuels, though the measured higher-heating value
(HHV) was lower (29.8 MJ kg-1). The reaction temperature was explored in the range
280–350 °C and biocrude oil yield and HHV reached their maxima at the highest
temperature. Slurry concentration was explored between 15–30% at this temperature
and the best HHV, O:C and N:C was found to occur at 25%. Two solvents
(dichloromethane (DCM) and n-hexane) were used to recover biocrude oil, affecting
the yield and chemical composition of the biocrude.
KEYWORDS: Microalgae, HTL, biocrude, FAME, fuel properties.
Chapter 5: Experimental investigation of physical and chemical properties of microalgae biocrude using a large
batch reactor 67
5.1 INTRODUCTION
Microalgae are of considerable interest for the production of next-generation
biofuels [10, 32] that are indistinguishable from petroleum fuels based on their
properties [2]. This is because using microalgae for biofuel production would have
fewer adverse effects on food supply and other agriculture [167, 168] as they can be
cultivated on non-arable land using fresh, waste or saline water sources, enable more
efficient nutrient recycling and achieve higher productivities [169, 170].
A range of conversion techniques are under development to generate biofuels
from microalgae. These include solvent extraction followed by trans-esterification to
produce fatty acid methyl esters (FAME), fermentation to alcohols, as well as
thermochemical conversion pathways such as pyrolysis and hydrothermal liquefaction
(HTL) [171, 172] to produce biocrude oils. HTL efficiently converts wet microalgae
biomass feedstock into biocrude oil [51, 54, 173] as it eliminates the need for
expensive pre-drying of the raw material. Compared to trans-esterifying lipids
obtained from microalgae by solvent extraction, HTL has the potential to require less
energy for the conversion process, which would improve production costs [71]. The
high-solvent losses associated with FAME production means its financial viability is
directly related to the lipid content (high lipid content being better) whereas HTL can
make use of more highly-productive microalgae species (i.e. more tonnes per hectare),
which have higher carbohydrate content, lower lipid content and the potential for
additional co-products [174]. These advantages of HTL make it a competitive route
for the conversion of raw microalgae biomass to fuels [51, 54, 173].
HTL converts microalgae biomass into biocrude oil as well as aqueous, gas and
solid phase products at elevated pressures (5–24 MPa) and moderate temperatures
(250–400 °C) [68, 69]. A wide range of microalgae biomass feedstocks has been
explored using HTL, including laboratory and commercially grown strains
Botryococcus braunii [55], Arthrospira (Spirulina), Scenedesmus sp [175]. and
Tetraselmis sp. [32]. Among the green microalgae the most common Scenedesmus sp.
has high productivity although the lipid yield can be optimised to reach over 60%
[176], which makes this strain attractive for biofuel production. In general, the
variation in the biochemical composition, particularly the carbon-chain length and the
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 68
degree of saturation, affects the conversion rate and the chemical-physical properties
of the HTL biocrude [57, 177].
The effect of operating conditions such as residence time, temperature, slurry
concentration and catalyst, on physical and chemical properties of microalgae HTL
biocrude have been investigated previously in limited studies [47, 49, 178, 179]. In
this study, three temperatures and slurry concentrations were investigated in the range
280–350 °C and 15–30% respectively; temperature and concentration, as well as
reaction time of 60 min was based loosely on literature [49, 51]. Higher temperatures
were not explored so as to remain below water’s supercritical point. Jena et al. [49]
demonstrated that among the various process parameters the temperature had the
strongest influence on the higher-heating value (HHV), viscosity and chemical
composition. HTL produces biocrude oil that by weight can have 6 to 8 times higher
oxygen and nitrogen content than heavy fuel oil (HFO) [97]. The inorganic salts in
many types of HTL biocrude oil require modifications to be compatible with a
traditional refining process [32, 51, 72, 180]. Biocrude oil may also need subsequent
upgrading to improve quality and reduce these undesired components.
Most experimental research in HTL continues to use small-batch reactors (less
than 1000 ml), while scale-up reactors are usually continuous. The kinetics of small
size reactors or autoclaves may differ from large ones, both batch and continuous,
which lead to different chemical reactions. Therefore, the results from these reactors
are not fully reliable in terms of scale-up. Batch reactors are commonly used to validate
the process conditions for further commercial scale. Although industry tends to prefer
continuous reactors to batch reactors because of higher energy efficiency, the steady
production rate and uniformity of product, large-batch reactors still have several key
advantages:
Pumping the biomass slurry into continuous reactor at high pressure and
temperature remains technological challenge at industrial scale
Ability to switch easily between feedstocks.
For a factory, individual reactors can be taken out-of-service for maintenance.
Due to the lack of biocrude for testing, most groups only reported values at
optimised parameters. The aim of this study was to conduct more comprehensive
Chapter 5: Experimental investigation of physical and chemical properties of microalgae biocrude using a large
batch reactor 69
experimental analyses with three key objectives; (i) to empirically investigate the
relationship between the reaction parameters and experimentally determined values
for biocrude oil’s physical properties of biocrude, (ii) to evaluate how the chemical
composition varies with operating conditions, and (iii) to identify the best possible fuel
physical and chemical properties of microalgae HTL biocrude. Both physical and
chemical properties are needed to meet legislated diesel and FAME biodiesel
standards. In further analysis, the physical properties of the optimal biocrude were
compared with other fuel standards to determine the similarities and reveal areas for
improvement.
5.2 MATERIALS AND METHODS
5.2.1 Hydrothermal Liquefaction (HTL)
The experiments were performed in a 1.8 L batch reactor system (Parr
Instruments Co.) and data were collected across three physical variables: temperature,
slurry concentration, and solvents for recovering the biocrude from the liquid mixture.
The experimental temperatures used were 280 °C, 300 °C and 350 °C, and solid
concentrations in the slurry were 15%, 25% and 30% by weight. When loading the
reactor, the headspace was purged thoroughly using nitrogen to remove oxygen, and
pre-pressurised to 2 bar with nitrogen gas. The reactor was heated to the desired
temperature (heating rate ~3.3 °C/min) and held constant for one hour, which is
consistent with the literature [49, 181-185]. At the end of the reaction time, the reactor
was cooled by passing water through an internal cooling tube until room temperature
was reached. Experiments were performed in duplicate and the average yield of two
runs is reported. After the gas was vented from the reactor, the vessel was opened and
the mixture was separated (following the steps in Figure 5.1). The walls of the reactor
were washed thoroughly with solvent (dichloromethane (DCM) or n-hexane) and
mixed with the liquid phase. The amount of solvent added was determined as the
volume of the solvent per mass dry weight of algae. The solid phase was removed from
the liquid mixture by vacuum filtration before being washed with the remaining
solvent. The solids were then oven-dried at 105 °C overnight.
The liquid phase mixture was poured into a separation funnel and the water-
insoluble components (organic phase) were separated from the water soluble (aqueous)
phase. The solvent was evaporated from the biocrude by a rotary vacuum evaporator.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 70
Due to the volatile nature of DCM we have used 40°C 760 Tor and placed an additional
trap between the vacuum source and the condenser unit. Whereas for n-hexane the
temperature was set up at 68 °C (760 Tor). The evaporation was continued until no
further yield was obtained. The time for the DMC was shorter than that for n-hexane.
Liquefaction of biomass slurry
Products mixture
Gas fractionWashing with
solvent
Liquid and solid
fraction
Vacuum filtration
Solid
residues
Liquid
fraction
Addition of solvent/phase separation
Organic phase Aqueous phase
Solvent removal
Solvent fractionWater soluble
fraction
Solvent removal/
Vacuum evaporation
Bio-crude oil
Figure 5.1: HTL product recovery workflow.
5.2.2 Raw materials
A robust and fast-growing green freshwater microalga, Scenedesmus sp., which
had been isolated as part of previous work [186], was used for these experiments. The
Scenedesmus sp. bulk biomass was produced at the University of Queensland’s Solar
Biofuels Research Centre facility at Pinjarra Hills near Brisbane, Australia. High
density slurry was frozen and stored at -20 °C directly after harvest to prevent
degradation during the HTL experiments. Proximate analyses were performed
Chapter 5: Experimental investigation of physical and chemical properties of microalgae biocrude using a large
batch reactor 71
according to American Society for Testing and Materials (ASTM) standards and using
a thermo-gravimetric analyser (TGA–NETZSCH thermal analyser). Ultimate analyses
were carried out using a LECO TruSpec Micro CHNS elemental analyser (Table 5.1).
The HHV of the dried microalgae sample was calculated according to the formula used
by Demirbas [187] and Friedl [188], which were 18.07 MJ kg-1 and 19.5 MJ kg-1
respectively for Scenedesmus species microalgae. The lipid content for the samples
used in this study was typically 15–20%.
Table 5.1: Microalgae proximate and ultimate analyses data.
Proximate analyses Ultimate analyses
Composition Percentage of weight
Element Percentage of weight
Fixed carbon 24.8 C 46.3
Volatile matter 67.3 H 6.9
Ash 3.2 O 32.3
Moisture 85 N 7.3
S 2.3
5.2.3 Analytical methods
The conversion and product yields were defined as the mass fraction of the
respective product (i.e. biocrude and solid residue) as a function of the initial mass of
biomass. For approximation, the total yield of gas + aqueous products were determined
by difference according to the approach commonly used in the literature [e.g. 189].
Solid residues (wt. %) = (mass of solid residues
mass of raw material ) x 100 ………………… (5.1)
Biocrude yield (wt. %) = (mass of bio−crude
mass of raw material ) x 100 ………………… (5.2)
5.2.4 Biocrude properties measurements
The chemical and physical biocrude properties such as higher-heating value
(HHV), viscosity, density and chemical composition were measured experimentally.
HHV of the biocrude was measured with a Parr 6200 compensated jacket calorimeter.
For comparative purposes, the correlations used for fossil fuels (liquid, gas and coal),
and that form the basis of calculation applied in other research articles, are Boie’s and
Dulong’s formulae, which are shown equations 5.3 and 5.4 respectively [187, 190].
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 72
HHV (MJ/kg) = 35.16 C + 116.225 H – 10.09 O + 6.28 N + 10.465 S----- (5.3)
HHV (MJ/kg) = 0.3383C + 1.422 (H – O/8) ----------------------------------- (5.4)
A Brookfield DV-III ultra-programmable rheometer was used to measure the
viscosity of the biocrude at constant temperature. The accuracy of the rheometer for
viscosity measurements is ±1.0% of full scale range for a specific spindle running at a
specific speed. The density of the biocrude was measured using German industrial
standard (DIN) 1306.
Gas Chromatography with Mass Spectroscopy (GC-MS) was used to identify
the chemical compositions in the biocrude samples. GC-MS analyses were performed
using a Thermoscientific, Trace 1310 system, equipped with a single quadrupole mass
selective detector (ISQ). Each sample was dissolved and diluted in DCM. The injector
was set to 250 °C and a Thermo TG-5MS (30 m long, 0.25 mm ID, 0.25 mm
film) column was used. The oven was programmed at an initial temperature at 50 °C
(held 1/min) then heated at a constant rate of 10 °C min-1 until a temperature of 250
°C was reached, and then held for 9 min with a split ratio of 1:25 and a column flow
of 1.4 mL min-1. The MS detector scanned from 40–400 m/z with a solvent cut time
of 1.8 min and the ion source and transfer line temps were both set at 250 °C. The
carrier mode was set to constant flow.
5.3 RESULTS AND DISCUSSION
To investigate the influence of reaction conditions on product yields, HTL was
conducted using a range of reaction temperatures, solid concentrations, and two types
of solvents (DCM and n-hexane) to recover the biocrude.
5.3.1 Influence of solvents in product separation
After completion of HTL, the biocrude must be separated from the aqueous and
solid phases. The most common solvents reported in the literature, with a focus on
maximising biocrude yield, are the organic solvents DCM, chloroform, acetone and
n-hexane [178, 185, 191]. However, there was insufficient information about the
effect of these polar and non-polar solvents on the biocrude quality. The data presented
in Figure 5.2 was obtained from experimental runs with 25% slurry concentration at
350 °C for 60 min in a nitrogen atmosphere.
Chapter 5: Experimental investigation of physical and chemical properties of microalgae biocrude using a large
batch reactor 73
Figure 5.2: Effect of solvent on the recovery of biocrude, solids and gas + aqueous
components after HTL treatment (350 °C, 60 min, 25% slurry concentration).
Suitable nonpolar (n-hexane) and more polar (DCM) solvents were selected
based on previous studies and the product yields and chemical composition were
compared (see section 3.4). For the same algae species, and under identical reaction
conditions, biocrude yield varied from 31.2% (wt.) with n-hexane to 33.6% (wt.) with
DCM. This differed from the results of Valdez et al. (2011) who obtained the highest
biocrude yield (39%) with nonpolar solvents (hexadecane and decane) and the lowest
value with 30 % DCM for Nannochloropsis sp. at 350 °C for 60 min [185]. This
supports the view that both biomass properties and the solvent type used for separating
products after HTL has an influence on biocrude recovery. However, as n-hexane has
a higher boiling point than DCM, this could lead to higher losses of volatile
compounds during the evaporation process and this could possibly account for the
small difference (2.4%). Despite this, DCM was used as a solvent of choice for product
separation in all subsequent experiments.
5.3.2 Effect of reaction temperature on yield and HHV The effect of three different temperatures (280, 300, 350 °C) was investigated
using a 60 min reaction time and a nitrogen atmosphere at an initial pressure of 2 bar
(Figure 5.3). Biocrude yield increased with temperature from 24.5% at 280 °C to
32.5% at 300 °C and reached a maximum of 33.6% at 350 °C, in the range analysed.
33.6 31.2
15.3 15.9
51.1 52.9
0
10
20
30
40
50
60
DCM n-Hex
Yie
ld (
%)
bio-crude
SR
gas+aqueous
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 74
Similar results for temperature’s influence on biocrude yield have been reported
recently [49, 178, 183, 192]. The HHV was characterised for biocrude generated at
temperatures of 300 °C and 350 °C only, due to an insufficient amount of biocrude at
280 °C. The HHV followed the trend of biocrude yield; it increased from 26.1 MJ.kg-
1 to 29.8 MJ.kg-1, which was approximately 50% higher than in the original microalgae
biomass. The solid residue yield decreased gradually from 20.1% to 15.3% with rising
temperature suggesting organic conversion mostly into the aqueous and gas phases.
These outcomes generally support processing at the higher temperature range where
biocrude yield was maximised. Higher temperatures than these were not investigated
because of potential corrosion issues related to supercritical fluids. To this end, 350 °C
was used for future experiments.
Figure 5.3: Influence of the reaction temperature on product yields at 25% solids
concentration and 60 min reaction time in a nitrogen atmosphere (2 bar at
commencement), values are for yield data.
5.3.3 Effect of solid concentration on yield and HHV Liquefaction of Scenedesmus sp. was conducted at 350 °C for 60 min in a
nitrogen atmosphere using a range of algae slurry concentrations between 15 to 30%
by weight (Figure 5.4). These results show that the solid concentration of algae slurry
may have had a minor had a modest effect upon the biocrude yield (ranging between
~28.9–33.6%) and HHV (26.5–29.8 MJ.kg-1) with the highest yields and HHV
observed at 25% biomass concentration. However, the slurry concentration did have a
25
27
29
31
33
35
0
10
20
30
40
50
60
70
280 300 350
HH
V (
MJ/
kg)
Yie
ld (
% w
t.)
Temperature (°C)
Bio-crude SR Gas + aqueous HHV
Chapter 5: Experimental investigation of physical and chemical properties of microalgae biocrude using a large
batch reactor 75
significant effect upon chemical speciation (see section 5.3.4). A similar trend for
biocrude and the water soluble fraction was reported by Jena et al. (2011). The fact
that biocrude yield peaked at the 25% slurry concentration suggests that the substrate
was limiting at lower concentrations and that H+ and OH- ions responsible for
liquefaction become limiting at higher concentrations [49]. The presence of active
hydrogen formed from the water under HTL conditions stabilises the biomass
liquefaction intermediates. This prevents formation of more new compounds that do
not decompose easily, producing a higher yield of biocrude [193]. The yield of the gas
+ aqueous fraction ranged between 51.1%–60.6% over the slurry solid concentration
range tested and the lowest yield 51.1% was observed at 25% solid concentration,
which corresponded with the highest biocrude yields. Solid residues increased from
10.5% to 17.1% with slurry concentration due to the increase of solid mass fraction in
the slurry. This corresponded with the report of Jena et al. [49] where solid residues
had a small increase (5.4%–7%) with solids concentration in range from 10%–50%
[49].
Figure 5.4: Effect of slurry concentration on the recovery of biocrude, solids and gas
+ aqueous components after HTL treatment (350 °C, 60 min). Standard deviations
are based on 2 replicates; values provided are for yield data.
25
26
27
28
29
30
31
0
10
20
30
40
50
60
70
15 25 30
HH
V (
MJ/
kg)
Yie
ld (
% w
t.)
Slurry concentration (%)
Bio-crude SR Gas + aqueous HHV
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 76
5.3.4 Chemical characterisation of biocrude oil The chemical composition of each biocrude oil sample was characterised by GC-
MS. Due to the complex composition of the biocrude oil, only abundant compounds
were evaluated based on the peak areas (defined by the percentage of the
chromatographic area of the compound out if the total area). GC-MS revealed distinct
amounts of chemical compounds, which consisted of more than 2% of the total area
within the retention time range of 3–34 min. Around 64 compounds were identified
which accounted for approximately 80–90% of the total peak area from all bio-oil
samples and 28 of them are listed in Table 5.2 and Table 5.3. The majority of the
compounds obtained were cyclic nitrogenates (e.g. pyrolle, pyrazine, piperidine) and
cyclic and aromatic oxygenates (e.g. phenols, ketones), which is similar to previous
studies [49, 175, 182]. These compounds are formed from carbohydrates and proteins
obtained from the feedstock that undergo depolymerisations, decompositions and
reformation [194]. The minor compounds were mostly hydrocarbons (HCs) and esters,
which may be derived from lipid content. Lipids can produce stable HCs via
decarboxylation and decarbonylation reactions [194, 195]. The tables show a
comparison of the identified chemical compounds in the biocrude oil under different
reaction conditions.
Table 5.2 presents only the key compounds that were identified through GCMS
for both solvents. It shows the effectiveness of the n-hexane and DCM in terms of the
extraction of biocrude oil from the water-soluble fraction, independently. DCM and
n-hexane extracted 57.1% and 40.2% of heterocyclic and aromatic compounds
(mostly nitrogenated) from the water, respectively. Ketones were the most abundant
oxygenated compounds. Neither solvent had a strong influence on aliphatic recovery
rates, although a slight increase was observed with DCM. Valdez et al. (2011) also
reported that the total yields of aliphatic compounds did not vary significantly between
the polar to nonpolar solvents. They also found that DCM extracted more light low
molecular products such as aromatics, nitrogen-, oxygen- and sulphur obtaining
compounds, than n-hexane [185].
Chapter 5: Experimental investigation of physical and chemical properties of microalgae biocrude using a large
batch reactor 77
Table 5.2: Major compounds of recovered bio-oils obtained from HTL (350 °C, 60
min, 2 bar nitrogen atmosphere) using two different extraction solvents (DCM and n-
hexane).
RT
(min) Name of compound
Area %
DCM
n-
hexane
4.5 4-hydroxy-4-methyl , 2-pentanone 5.03 -
4.82 Ethylbenzene 8.86 3.38
4.98 1,4-dimethyl ,benzene 11.99 6.34
5.44 1,3-dimethyl ,benzene 3.44 5.12
5.82 2,5-dimethyl-,pyrazine 4.09 -
6.91 2,6-dimethyl-, 4-heptanone - 4.74
7.54 Trimethyl pyrazine 2.76 4.3
7.79 2,3,5-trimethyl-, 1H-pyrrole - 3.06
8.18 2,3-dimethyl-, 2-cyclopenten-1-one 5.32 4.36
8.49 3,7-dimethyl ,undecane - 2.82
8.77 4-methyl , phenol 3.53 4.45
9.06 1- acetate 1,2,3- propanetriol 2.99 7.11
9.21 Undecane - 3.91
9.32 1-ethyl-2-pyrrolidinone 10.38 -
10.08 2,2,5,5-tetramethyl-,3-cyclopenten-1-one - 5.15
11.42 1-butyl-, 2-pyrrolidinone, 4.25 2.72
12.93 1-pentyl-, piperidine 3.78 4.84
13.49 2-methyl-, 3-hydroxy-2,4,4- trimethylpentyl ester,
propanoic acid, - 5.11
24.91 Di(2-propylpentyl) ester , phthalic acid 10.78 -
Total 77.2 67.41 - , chemical compounds either not detected or peak area less than 2%.
Table 5.3 presents the variation of key chemical compounds from the biocrude
oil samples produced with a microalgae mass fraction in the feed ranging from 15%–
30% under various temperatures 280°C–350°C). The main compounds include:
nitrogenated compounds (pyrolle, pyrazine, piperidine); oxygenated compounds
(phenols, ketones, esters); aliphatics (alkanes, alkenes); and aromatics (benzene).
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 78
Table 5.3: Major compounds of recovered bio-oils obtained from HTL under various
solid concentrations and temperature using (DCM).
RT
(min) Name of compound
Area (%)
Slurry Concentration Temperature
15% 25% 30% 280
°C
300
°C
350
°C
4.01 2-methyl , pyrimidine 3.92 - 4.05 4.94 8.18 -
4.41 4-hydroxy-4-methyl , 2-
pentanone - 5.03 - 23.81 4.15 4.03
4.82 Ethylbenzene 0.68 8.86 - 1.34 1.75 8.86
4.97 1,4-dimethyl , benzene - 11.99 - 2.48 2.77 11.30
5.67 2-methyl , 2-cyclopenten-
1-one 4.71 - 2.72 9.19 10.03 -
5.79 2,5-dimethyl , pyrazine 4.84 4.09 3.53 12.18 12.4 4.09
6.8 3-methyl , 2-cyclopenten-
1-one 6.66 4.86 2.31 2.7 6.0 4.5
7.1 Phenol 3.24 3.33 2.16 - 2.43 3.32
8.15 2,3-dimethyl , 2-
cyclopenten-1-one 12.86 12.04 5.32 2.29 5.73 6.05
9.03 1- acetate 1,2,3-
Propanetriol, 4.72 5.09 5.63 2.58 4.22 5.19
9.27 Undecane 9.20 11.12 12.62 2.49 5.9 8.99
9.94 1,3-diethyl-3-methyl ,
2,5-pyrrolidinedione, 2.27 2.5 2.72 - 2.48 2.51
10.69 1-propyl , 2-
pyrrolidinone, 3.04 2.32 3.48 - - 2.30
11.39 1-butyl , 2-pyrrolidinone 3.3 4.25 3.16 - - 4.20
24.91 Di(2-propylpentyl) ester,
phthalic acid - 10.78 8.25 - - 10.78
- , chemical compounds either not detected or peak area less than 2%.
As shown in Table 5.3, cyclic oxygenated compounds (mostly ketones such as
2, 3-dimethyl, 2-cyclopenten-1-one), are slightly decreasing with increasing solids
concentration. This was in contrast to the aliphatic components, such as undecane,
which increased with the solid concentration. Cyclic nitrogenated and oxygenated
compounds including 1-butyl, 2-pyrrolidinone; 1, 3-diethyl-3-methyl, 2, 5-
pyrrolidinedione; 1-propyl, 2-pyrrolidinone were the most abundant in each sample.
In the low temperature reaction at 280 °C, biocrude oil had the highest amount of
oxygenated compounds—mostly aliphatic, prevalent ketones including 4-hydroxy-4-
methyl, 2-pentanone; 2-methyl, 2-cyclopenten-1-one; 2,3-dimethyl, 2-cyclopenten-1-
one. Abundance of HCs and aromatics were the lowest for the biocrude oil at 280 °C
but had the highest percentages at 350 °C. The number of identified nitrogenated
Chapter 5: Experimental investigation of physical and chemical properties of microalgae biocrude using a large
batch reactor 79
compounds such as pyrazine, 2-methyl, 2, 5-dimethyl, pyrimidine; trimethyl and
pyrazine, initially, increased with temperature and reached the maximum at 300 °C
after which it decreased. Jena et al. obtained similar results from biocrude oil
comparing five different temperatures [49]. Esters such as di (2-propylpentyl) ester,
phthalic acid; 15-methyl-, ethyl ester, heptadecanoic acid, were observed only in the
highest temperature. The detailed analysis shows the strong dependency of chemical
compounds on process condition.
5.3.5 Effect of temperature and concentration on chemical and physical
properties
Both the chemical and physical properties of biofuels are important to define
fuel quality in terms of combustibility, density, energy content, and lubricity. These
fuel properties vary with chemical composition and influence engine performance and
emission results [57, 73-77]. It was observed that the chemical components and
compositions of the biocrude varied with the process conditions (Table 5.2 and Table
5.3), which subsequently affected the fuel’s physical properties. Table 5.4 shows the
effect of temperature and concentration on ultimate analysis and HHV of the
microalgae biocrude. The chemical and physical properties of microalgae HTL
biocrude are shown in Table 5.5 and compared with FAME microalgae biofuel and
mineral diesel.
Biocrude chemical composition
The extracted biocrude contained a range of complex HC groups including
aliphatics, aromatics, as well as nitrogenated and oxygenated compounds. HCs mostly
contained either oxygen or nitrogen in the C-H chain. Table 5.4 shows the elemental
composition of the biocrude obtained at different temperatures with 25% slurry
concentrations and for different slurry concentration at 350 °C. The elemental analysis
showed that the mass percentage of oxygen decreased from 16% to 10% with
increasing temperature of the experiment for 25% slurry. In contrast, the hydrogen
percentage was relatively stable: within 8.93–10.14% over the experimental range. The
differences in chemical composition and molecular structure (e.g. C, H and O
composition, straight chain, cyclic, and heterocyclic compounds) affect the physical
properties of the biocrude oil including HHV, density, viscosity, cetane number and
surface tension; important parameters for internal combustion (IC) engines. The slow
heat-up and cooling-down time can potentially lead to polymerisation and secondary
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 80
reactions. It is expected that the engine performance and exhaust emissions would be
different compared to FAME biodiesel. For instance, the oxygen creates a permanent
dipole moment, which results in stronger hydrogen bonding and oxygenated fuels with
increased molecular affinity. Consequently, compressibility is decreased because the
free space between the molecules is similar. A follow-on effect is an increase in NOx
[74]. Nabi et al. [81] has also shown NOx emissions and adiabatic flame temperature
and NOx emissions present a linear decrease with increasing oxygen content.
Table 5.4: Ultimate analysis and HHV of the microalgae biocrude.
Component
(% wt.)
25% slurry concentration at
different temperature
350 °C temperature at
slurry concentration
280 ˚C 300 ˚C 350 ˚C 15% 25% 30%
C 68.1 70.4 75.6 74.1 75.6 73.7
H 9.3 8.9 10.1 9.7 10.1 9.8
O 15.7 12.1 10.3 11.2 10.3 10.8
N 6.9 8.6 4.0 5.0 4.0 5.7
H:C 0.14 0.13 0.13 0.13 0.13 0.13
O:C 0.23 0.17 0.14 0.15 0.14 0.15
N:C 0.10 0.12 0.053 0.07 0.05 0.08
HHV (Cal.), MJ kg-1 33.5 34.3 37.4 36.4 37.5 36.5
HHV(Meas.), MJ kg-1 -- 26.1 29.8 26.5 29.8 28.0
O:C, N:C and H:C significantly affect fuel quality and emissions, and so
temperature variation and slurry concentration effect on biocrude were compared with
diesel and FAME biodiesel standards in the Van Krevelen diagram (Figure 5.5). It is
important to note that the lowest N:C and O:C were found at the same conditions that
gave maximum biocrude yield and HHV (i.e. 350 °C and 25% slurry concentration;
for this range, the authors viewed lower O:C to be more beneficial). Figure 5.5 shows
that O:C changes with respect to N:C ratio, and H:C is almost constant; so N:C and
O:C varied more than H:C. The HHV is the highest at 350 °C due to the low O:C and
relatively good H:C. N:C also sharply reduced at high temperature. The biocrude oils
were more similar to FAME biodiesel than fossil fuel diesel in terms of H:C while the
nitrogen concentration was much higher than diesel and biodiesel standards due to the
high amount of proteins in the raw feedstock. We note that if n-hexane had been used
for the extraction rather than DCM the polarity of the biocrude would fall and
consequently the point would shift to the left on Figure 5.5 due to the lower oxygen
content.
Chapter 5: Experimental investigation of physical and chemical properties of microalgae biocrude using a large
batch reactor 81
Figure 5.5: Van Krevelen diagram of biocrudes gained for different temperatures
(280, 300 and 350 °C) and slurry concentrations (15%, 20% and 30%) in comparison
with diesel and FAME biodiesel standards [196].
The separated biocrude oil samples had a dark colour, high viscosity and an acrid
smoky odour. Chemical and physical properties were analysed for the optimal
biocrude produced at 350 °C, and 25% initial solids concentration and compared with
various types of fuel standards (Table 5.5).
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 82
Table 5.5: Comparison of chemical and physical properties of biocrude produced at
350 °C and 25% solids with trans-esterified microalgae biodiesel, diesel, biodiesel
and marine fuels standards [52].
Name of the
properties
HTL
Scenedesmus
sp. biocrude
oil
FAME
Crypthecodi
nium
cohnii
biodiesel
Biodiesel
Standar
ds
EN
14214
Petroleum
Diesel Marine
fuels
ISO
8217
Kinematic viscosity@40°
C (mm2 s-1)
70.7–73.8
5.06 3.5–5 2.64 1.4–
11.0
Density@15° C (kg L-1) 0.97* 0.91 0.86–0.9 0.84 0.96–
0.99
HHV (MJ kg-1) 29.7 39.8 - 44 44–45
Oxygen content (wt. %) 10.3 10.4 - 0 -
Hydrogen Content (wt. %) 10.1 11.1 - 13.8 -
Carbon Content (wt. %) 75.5 78.4 - 86.1 -
Nitrogen Content (wt. %) 3.97 0 - 0 -
Viscosity
At the optimum conditions, the viscosity of the HTL microalgae biofuel was
closer to conventional diesel and biodiesel than FAME from microalgae and varied
with chemical composition, possibly due to the varying degree of chemical saturation
[197]. The variation of biocrude compositions influenced the intermolecular forces.
The variation in viscosity can potentially affect injection timing, spray, atomisation
and combustion compared to microalgae FAME [180]. There is a possibility to use
biocrude in a heavy-duty diesel engine or a marine-ship engine with minimal
upgrading.
Density
The fuel density affects the mass of fuel injected because fuel injection systems
in modern diesel engines measure the fuel on a volume basis [74]. At optimal
conditions, the density of the HTL microalgae biocrude was 13% higher than
conventional diesel fuel and not comparable with any fuel standards in Table 5.5. The
increased density of the HTL microalgae biocrude might be due to it containing many
aromatic HCs and cyclic chemicals as well as an amount of high molecular weight
compounds that are beyond detection in GC-MS. However, the density value (0.97
Chapter 5: Experimental investigation of physical and chemical properties of microalgae biocrude using a large
batch reactor 83
kg.L-1) is comparable to the marine residual fuel standard ISO 8217:2012 (0.96–0.99
kg.m-3).
HHV
Among the fuels, the HHV of microalgae biocrude had the lowest value at 29.8
MJ.kg-1 (best H:C) [24]. Enrichment in double bonds generally results in lower than
expected levels of heats of combustion due to strong intra-molecular bonding [198].
The vapour heat capacity and thermal conductivity relates to the heating value of the
fuel. These affect droplet-surrounding heat transfer, temperature distribution and the
mass air fuel ratio that will reduce combustion performance [199].
5.3.6 Comparison with previous studies
The findings of this study are compared with previous studies in Table 5.6 where
most researchers worked with very small-batch reactors (<100 ml), although there
have been a few studies with larger continuous reactors (typically ~1000 ml). The vast
majority of HTL studies report physical properties, HHV in particular, derived from
correlations, which use elemental analysis results for gaseous, liquid, coal and biomass
materials [187, 190]. Our calculated values for HHV are similar to those reported
elsewhere but we also report a much lower measured value, which was also reported
by Li [93], despite the different oxygen content.
The density and viscosity of the biocrude are not widely reported (Table 5.6).
The biocrude viscosity was significantly closer to regular diesel and biodiesel
standards than transesterified (FAME) microalgae biodiesel. Under optimised
conditions, HTL biocrude’s high density (0.97–1.04 kg L-1) and its high viscosity
(3.61–3.37 mm2 s-1) had enough similarity to marine heavy fuels that it could be
immediately used without further processing, although the measured HHV was lower
(29.8 MJ kg-1).
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 84
Table 5.6: Comparison of results from this study with literature.
HTL biocrude
Reactor type
Reactor volume (ml)
Operating conditions
Physicochemical properties
Temp. (°C)
Time (min)
Yield wt %
Chemical composition % HHV (MJ/kg) Kinematic viscosity (mm2/s)
Density (kg/L)
Refer-ences
C H N O Calcu- lated
Meas- ured
Scenedesmus sp.
Batch reactor
1800 350 60 33.6 75.6 10.1 3.97 10.3 37.4 29.8 70.7–73.8 0.97 Current study
500 300 30 45 72.6 9.0 6.5 10.5 35.5 - - - [200]
Enteromorpha prolifera
25 300 30 23 64.5 7.7 5.4 22.4 30.8 - - - [50]
Lemna sp. 25 350 30 17.5 72.1 7.8 4.6 15.5 32.8 - - - [95]
Laminaria saccharina
75 350 15 19.3 82.0 7.1 4.9 6.0 37.4 - - - [72]
Chlorella pyrenoidosa
17.2 350 60 41 75.1 9.9 7.3 7.7 38.1 - - - [94]
Nannochloropsis sp
35 350 60 43 76.0 10.3 3.9 9.0 39 - - - [183]
Enteromorpha prolifera
25 370 40 31.7 77.9 9.6 5.6 6.9 39.4 - - - [51]
Sargassum patens C. Agardh
1000 340 10 32.1 64.6 7.4 2.5 25.5 - 27.1 - - [93]
Saccharina sp. Continuous-flow reactor
1000 340 87 58.8 79.4 8.0 4.1 8.5 37.5 - - - [53]
NB238 1000 350 38 78.6 10.4 4.2 5.3 - - - - [201]
Chapter 5: Experimental investigation of physical and chemical properties of microalgae biocrude using a large
batch reactor 85
5.4 CONCLUSION
This paper studied the impact of HTL operating conditions (reaction temperature
and slurry concentration) on the chemical compositions and the subsequent physical
and chemical properties of the microalgae biocrude. Physical properties were able to
be measured experimentally because of the larger scale of the reactor rather than being
derived using correlations based on elemental analysis. We note a significant
difference in the calculated and measured values, which is consistent with the
literature. The highest biocrude oil yield (33.6%) was produced at 350°C and at 25%
solids concentration. The aliphatic, aromatic, nitrogen-containing hetero-cyclic,
oxygenated compounds were the major group of components of HTL microalgae
biocrude. These conditions also produced the lowest O:C and N:C. The biocrude had
higher density and lower HHV than diesel and biodiesel and was closer in character to
HFO where it could be used directly. Future work will focus on further improving
chemical and physical properties, such as HHV, density, and decreasing N and O
percentages, via catalytic upgrading, or via reactions in-situ, followed by engine
testing.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 86
5.5 ACKNOWLEDGMENTS
This work was financially supported by the QUT ECARD program and by a PhD
scholarship from the QUT School of Chemistry, Physics and Mechanical Engineering.
The authors thank to the QUT Central Analytical Research Facility for their assistance.
Chapter 6: Investigation of microalgae HTL fuel effects on diesel engine performance and exhaust emissions
using surrogate fuels 87
Chapter 6: Investigation of microalgae
HTL fuel effects on diesel
engine performance and
exhaust emissions using
surrogate fuels
Farhad M. Hossain1, 2*, Md. Nurun Nabi3, Thomas J. Rainey1, 2, Timothy Bodisco4,
Md Mostafizur Rahman5, Kabir Suara1, Rahman S.M.A 1,2, Thuy Chu Van 1,2, Zoran
Ristovski1,2 and Richard J. Brown 1, 2,
1 Biofuel Engine Research Facility, Queensland University of Technology (QUT), Brisbane,
Queensland 4001, Australia 2 QUT, International Laboratory for Air Quality and Health 3 School of Engineering and Technology, Central Queensland University, Perth, WA 6000, Australia. 4 School of Engineering, Deakin University, Waurn Ponds, Victoria 3217, Australia 5 Rajshahi University of Engineering & Technology, Department of Mechanical Engineering,
Bangladesh
Statement of contribution of Co-Authors for this publication
The authors listed in the table below have certified that:
1. they meet the criteria for authorship in that they have participated in the conception, execution, or
interpretation, of at least that part of the publication in their field of expertise;
2. they take public responsibility for their part of the publication, except for the responsible author who
accepts overall responsibility for the publication;
3. there are no other authors of the publication according to these criteria;
4. potential conflicts of interest have been disclosed to (a) granting bodies, (b) the editor or publisher of
journals or other publications, and (c) the head of the responsible academic unit, and
5. they agree to the use of the publication in the student’s thesis and its publication on the Australasian
Research Online database consistent with any limitations set by publisher requirements.
Title and status: Investigation of microalgae HTL fuel effects on diesel engine
performance and exhaust emissions using surrogate fuels (Published at Energy
Conversion and Management-under review).
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 88
Contributor Statement of contribution
Md Farhad Hossain Candidate
Conducted the experimental work, performed data analysis, interpreted
the results, wrote the manuscript and acted as the corresponding author.
Signature
Date
Richard Brown Principal Supervisor
Conceptualised the design of instrument, aided the field experiments,
interpretation of the results, reviewed and edited the manuscript as a
principal supervisor.
Md Nurun Nabi Dr Md Nurun Nabi has been working as a Lecturer in the Department of
Mechanical Engineering at Central Queensland University (CQU), . He
has about 30 years of research experience in the field of engine exhaust
emissions.
Describe physicochemical properties effect of engine performance and
edited the manuscript.
Thomas Rainey Dr Thomas Rainey has 15 years of industrial and research experience in
biomass processing particularly in pulp and paper and sugar processing.
His research focuses on bioenergy and related value-added products.
Design concept of surrogate fuel and edited the manuscript.
Timothy Bodisco Dr Tim Bodisco has been working as a lecturer in the Department of
Mechanical Engineering at Deakin University. He has extensive
experience in engine experimental data analysis.
Dr Bodisco assisted in the analysis of cylinder data using his own matlab
code and edited the manuscript.
Md Mostafizur Rahman Dr. Md Mostafizur Rahman has been working as a Lecturer in the
Department of Mechanical Engineering at Rajshahi University of
Engineering & Technology.
Dr Md Mostafizur Rahman assisted with conducting the experiments.
Kabir Suara Dr Kabir Suara has been working as a Research Fellow at Queensland
University of Technology.
Dr Kabir assisted to analysis the data using matlab.
Rahman S.M.A Mr Ashrafur Rahman helped to conduct the engine experiment, especially
for PN measurements.
Chapter 6: Investigation of microalgae HTL fuel effects on diesel engine performance and exhaust emissions
using surrogate fuels 89
Thuy Chu Van Mr Thuy Chu Van helped to conduct the engine experiment, especially for
PM measurements.
Zoran Ristovski Professor Zoran Ristovski is a physicist who works at the Queensland
University of Technology as one of the leading researchers on vehicle
emissions with a special focus on particulate vehicle emissions.
Professor Zoran Ristovski designed and performed fuel properties related
to engine exhaust emissions and reviewed the manuscript as a co-authors.
Principal Supervisor Confirmation
I have sighted email or other correspondence from all Co-authors confirming their certifying
authorship.
Professor Richard J. Brown
Name Signature Date
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 90
Abstract
This paper builds on previous work using surrogate fuel to investigate advanced
internal combustion engine fuels. To date, a surrogate fuel of this nature has not been
used for microalgae hydrothermal liquefaction (HTL) biocrude. This research used
five different chemical groups found in microalgae HTL biocrude to design a surrogate
fuel. Those five chemical groups constitute around 65% (by weight) of a microalgae
biocrude produced by HTL. Weight percentiles of the microalgae HTL biocrude
chemical compounds were used to design the surrogate fuel, which was miscible with
diesel at all percentages. The engine experiments were conducted on a EURO IIIA
turbocharged common-rail direct-injection six-cylinder diesel engine to test engine
performance and emissions. Exhaust emissions, including particulate matter (PM) and
other gaseous emissions, were measured with the surrogate fuel and a reference diesel
fuel. Experimental results showed that without significantly deteriorating engine
performance, lower PM, PN and CO emissions were observed with a penalty in NOx
emissions for all surrogate blends compared to those of the reference diesel.
Keywords: Microalgae, surrogate fuel, diesel engine, emissions, PM, PN, NOx and
CO.
Chapter 6: Investigation of microalgae HTL fuel effects on diesel engine performance and exhaust emissions
using surrogate fuels 91
6.1 INTRODUCTION
Alternative fuels have become a key issue in the modern world due to the
depletion of fossil-fuel reserves, increasing fuel prices and issues relating to exhaust
emissions. Compared to petroleum diesel, biofuel has some advantages in relation to
emissions, including low emissions of carbon monoxide (CO), particulate matter and
unburned hydrocarbons (HCs) [31]. Hence, researchers have focused on the
development of biofuel and associated upgrading to meet fuel standards without
compromising engine durability [44, 45]. Many groups have investigated novel uses
of biofuel in diesel engines [6, 11, 65, 202, 203]. Unfortunately, most biofuels are not
able to be produced at an industrial scale. This is chiefly due to high production costs
and the fact that fuel properties may not be suitable for use in current diesel engines
due to their physiochemical properties. However, microalgae has recently received a
lot of attention as one option for producing biofuel as a renewable energy source
because it has minimal adverse effects on food supply and other agricultural systems
[10, 32, 204, 205]. Microalgae may be a potential feedstock for biofuel based on its
lipids and HCs [2, 206]. Various conversion techniques have been used to generate
biofuel from microalgae, including solvent extraction and hydrothermal liquefaction
(HTL) [32, 47, 180, 207].
HTL methods are gaining interest for producing biocrude. In liquefaction
methods, biomass is changed into gas, liquid and solids in a similar manner to
pyrolysis [48]. HTL is the most energetically advantageous thermochemical biomass
conversion process and it has been investigated with a wide range of microalgae
biomass feedstocks, including laboratory and commercially-grown strains
Botryococcus braunii [55], Spirulina and Tetraselmic sp. [32, 47]. Jena et al. [49]
studied the production of biocrude from Spirulina platensis. However, biocrude has a
higher oxygen and nitrogen content compared to reference diesel. In addition, HTL
biocrude contains inorganic salts and metals, which pose challenges within the
traditional refining process [32, 55, 72].
Therefore, microalgae-based biocrude requires further processing to improve
quality by reducing these undesired components. Chemical analysis of microalgae
biocrude reveals the presence of many chemical compounds in small quantities.
However, five chemicals contribute around 65% (wt.) of the total weight. In this study,
those five chemicals were blended to produce a surrogate fuel.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 92
Surrogate fuels are not new. Many researchers have developed diesel surrogate
fuels using various techniques [208-212]. Surrogates of diesel fuels are useful design
tools for developing engines with cleaner and more efficient combustion [212]. A
surrogate fuel is a mixture of pure chemicals to mimic the physicochemical properties
of a target fuel. Both physical and chemical fuel properties should be matched to the
surrogate fuel because those properties are important for engine operation,
performance and exhaust emissions. The chemical characteristics of the fuel include
molecular structure, flash point and C/H/O ration whilst physical characteristics
include HHV, density, viscosity and surface tension [208].
Pitz and Mueller [208] reviewed recent progress in the development of diesel
surrogate fuels. They investigated the status of chemical kinetic models and
experimental validation data of surrogate fuel components. They concluded that the
presence of higher molecular weight components is needed in models and
experimental investigations of surrogate fuel [208]. Dooley et al. [213] formulated a
jet surrogate fuel by real fuel properties. They used three chemical compounds—n-
decane, iso-octane and toluene mixture of 42.67, 33.02 and 24.31 (mol%)—to obtain
target surrogate properties [213]. Liu et al. [210] experimentally and numerically
investigated the combustion and emissions characteristics of diesel surrogate fuels in
a diesel engine. They investigated three different surrogates, including 85% (vol.) n-
heptane blended with 15% toluene (T15), 81% n-heptane blended with 14% toluene
and 5% c-hexane (T15 + CH5), and 80% (vol.) n-heptane blended with 20% toluene
(T20). They found the NOx and soot emissions were reasonably predicted. From the
modelling investigations, they inferred that the effects of physical properties on the
soot emission were larger than the effects of chemical properties of the different fuel
carbon-chain structures [210]. Das et al. [212] investigated sooting tendencies of diesel
fuels, jet fuels, and their surrogates in a diesel engine. They reported the opportunity
for developing new surrogates, composed of HCs with well-studied chemistry, which
can be used to replicate the sooting behaviour of most fuels [212]. Wu et al. [211]
experimentally investigated the miscibility of hydrogenated biomass-pyrolysis oil with
diesel as surrogate-ethylene glycol and its applicability to diesel engines. They found
that only 10% volume ethylene glycol could be mixed with diesel. They also reported
that there was no significant difference in specific fuel consumption, but found a
reduction in soot emissions [211]. Abboud et al. [214] tested the effect of the
Chapter 6: Investigation of microalgae HTL fuel effects on diesel engine performance and exhaust emissions
using surrogate fuels 93
concentration of oxygenated compounds on sooting propensities of surrogate diesel
and biodiesel. They found different behaviour for soot generation in both surrogate
diesel and biodiesel. They also reported that biodiesel-derived soot was smaller and
less reactive than diesel-derived soots [214].
The objectives of this study were to comparatively investigate the engine
performance and exhaust emissions of a series of microalgae HTL surrogate fuels on
a common-rail, multi-cylinder, turbo-charged diesel engine. The significance of this
research is to determine the thermal efficiencies and exhaust emissions of a new
surrogate fuel in a commercial diesel engine and establish a non-conventional fuel
application in a regular engine without modification. The performance of the engine
output is presented in terms of in-cylinder pressure and volume, brake power (BP),
brake mean effective pressure (BMEP), brake thermal efficiency (BTE) and brake-
specific fuel consumption (BSFC). Gaseous emissions of nitrogen dioxide (NO2),
nitrogen oxide (NOx), CO, particulate matter (PM) and particulate number (PN) were
compared.
To the authors’ knowledge, no investigation has been performed using a
microalgae HTL biocrude surrogate fuel to investigate performance and exhaust
emissions. This research will also provide fundamental knowledge for developing
microalgae biocrudes.
6.2 CONCEPT OF MICROALGAE HTL SURROGATE
In earlier experimental work, microalgae biomass were used to produce biocrude
using a HTL method. Two different variables were used as operating conditions:
temperature and slurry concentration. It was found that 25% slurry concentration and
350 ⁰C provided the best operating conditions. Further detail of the microalgae
biocrude operating conditions can be found in Farhad et al. [215]. It was also found
that microalgae HTL biocrude contains 13 main chemical compounds, seven of which
constitute 65% (wt.) of the total weight (i.e. under operating conditions with 25%
slurry concentration and 350⁰C) [215]. Those seven chemical compounds are
ethylbenzene, 1, 4-dimethyl-benzene, 3-methyl-2-cyclopenten-1-one, 2, 3-dimethyl-
2-cyclopenten-1-one, undecane, 4-hydroxy-4-methyl-2-pentanone and di(2-
propylpentyl) ester. These chemical compounds also contain key functional groups
present in the biocrude, including aromatics, cyclic ketones, alkanes, alcohols, and
aromatic FAMEs as shown in Figure 6.1 (results in duplicate). The horizontal red line
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 94
drawn at 5% (wt.) is used for illustrative purposes to elucidate which chemical
compounds are present at levels above 5%. Figure 6.2 shows the proportion of
compounds in microalgae HTL biocrude by functional group.
Figure 6.1: Weight percentage of chemical compounds in microalgae HTL biocrude.
Figure 6.2: Major chemical compounds of microalgae HTL biocrude [215].
6.2.1 Chemical compound for surrogate fuel
Each section of the surrogate palette is referred to as a surrogate chemical
compound. The surrogate chemical compounds were selected based on five key
0
5
10
15
% o
f H
TL
bio
-cru
de c
om
pou
nd
s
25% Slurry concentration @ 350 C_1
25% Slurry concentration@ 350 C_2
AlkaneCyclic ketone Aromatic FAMEAromatic Alcohol
Aromatics21%
Cyclic ketone17%
Alkane11%
Alcohel5%
Aromatic FAME11%
Others35%
Chapter 6: Investigation of microalgae HTL fuel effects on diesel engine performance and exhaust emissions
using surrogate fuels 95
functional groups: aromatics, cyclic ketones, alkanes, alcohols, and aromatic FAMEs.
Each are described in detail below.
Aromatics
Petroleum-based diesel contains around 25% of aromatic HCs [216]. They have
an impact on the cetane number and exhaust emissions of diesel engines, which means
improved engine performance. Aromatic HCs increase diesel engine particulate
emissions, which has long been of concern due to the toxic composition of the
emissions and the particle size distribution [217, 218]. Small, fine particles are
inhalable and penetrate deep into the lungs where they are able to enter the bloodstream
and even reach the brain [217, 219]. However, microalgae HTL biocrude contained
two aromatics in large quantities: 1, 4-dimethyl-benzene; and ethylbenzene. Their
chemical structures are shown in Figure 6.3 (a) and (b). Two methyl groups or an ethyl
group are attached to benzene. They are all colourless, flammable liquids.
(a) (b)
Figure 6.3: Chemical structure of (a)1,4 dimethyl, benzene and (b) Ethylbenzene.
Cyclic ketone
Two ketones (cyclic and straight chain) were found in microalgae HTL biocrude
in significant quantities. Figure 6.4 (a) and (b) shows cyclic ketone 3-methyl, 2-
cyclopenten-1-one, and 2, 3-dimethyl, 2-cyclopenten-1-one, which is contained in
microalgae HTL biocrude. However, both cyclic ketones are very expensive for the
purposes of engine testing, so cyclopentone (shown in Figure 6.4 (c)) was used instead
due to its functional similarity and low cost. It is also a colourless liquid with a petrol-
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 96
like odour. Cyclopentene is produced industrially in large amounts. It is used as a
monomer for synthesis of plastics, and in several chemical syntheses.
(a) (b) (c)
Figure 6.4: Chemical structure of (a) 3-methyl, 2-cyclopenten-1-one, (b) 2,3-
dimethyl, 2-cyclopenten-1-one and (c ) Cyclopentene.
Alkane
The majority of diesel fuel is made up of alkanes. Alkanes are straight-chain and
single carbon-carbon bond HCs. Petroleum-based diesel is composed of 75% saturated
HC, which are alkanes [216]. They are stable chemical compounds compared to
double- or triple-bond HC, which is called alkene and alkaline respectively. Straight-
chain alkanes are usually gaseous at room temperature; those with five to 15 carbon
atoms are usually liquids. The microalgae HTL biocrude contain about 11% (wt.)
undecane of the total biocrude weight. This chemical is low cost and can readily be
obtained. The chemical structure of undecane is shown in Figure 6.5.
Figure 6.5: Chemical structure of undecane.
Alcohol
The chemical compound 4-hydroxy-4-methyl-2-pentanone was found in the
microalgae HTL biocrude in significant quantities. This chemical contains both ketone
and hydroxide groups. It is also expensive. The chemical’s structure is shown in Figure
6.6 [220]. Butanol was selected to represent the alcohol group which occurs on a
number of biocrude compounds including (4-hydroxy-4-methyl-2-pentanone and 1-
Chapter 6: Investigation of microalgae HTL fuel effects on diesel engine performance and exhaust emissions
using surrogate fuels 97
acetate 1,2,3-propanetriol). Butanol is readily available and at a suitable cost compared
to 4-hydroxy-4-methyl-2-pentanone.
(a) (b)
Figure 6.6: Chemical structure of (a) 4-hydroxy-4-methyl and (b) butanol.
Aromatic FAME
The microalgae HTL biocrude contains a very irregular type of fatty acid methyl
ester (FAME): di-(2-propylpentyl) ester. This FAME contained aromatic ring in their
chemical structure, which is shown in Figure 6.7. In general, these compounds have
low toxicity.
Figure 6.7: Chemical structure of di-(2-propylpentyl) ester.
6.2.2 Design of microalgae HTL surrogate
There have been numerous engine studies using diesel surrogates [208-212,
214]. Most previous studies have involved up to six components [209, 211, 212]. The
current study provides a methodology for creating microalgae HTL surrogate fuel.
HTL microalgae biocrude contains many different chemical compounds from different
chemical groups. In addition, HTL biocrude contains inorganic salts and metals, which
bring challenges to the traditional refining process [32, 55, 72]. Therefore, the biocrude
requires further processing to improve quality by reducing these undesired
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 98
components. It is also noted that biocrude physicochemical properties are not similar
to regular diesel fuel, thereby preventing it being used directly in conventional diesel
engines (as a neat fuel). The approach for designing the target surrogate fuels with the
chemical groups is shown in Figure 6.8, while the final palette is shown in Figure 6.9.
The physicochemical properties of the target fuels were taken into account as design
parameters and the percentage of different chemical groups was decided according to
literature [208, 209]. The target fuel is a theoretical fuel with selected properties that
are to be matched by a surrogate fuel. Similarly, the design properties are the properties
of the target fuel that are to be matched by the surrogate fuel. The design properties
included CN, HHV, density, and the chemical composition of the fuel. The property
target for CN was 45 and 0.82–.084 (kg/L) for density. However, the reference
chemical groups were selected from the microalgae HTL biocrude list, which is shown
in Figure 6.1. The surrogate fuel properties are shown in Table 6.3 and compared to a
reference diesel fuel.
Microalgae HTL biocrude contained about 4% (wt.) nitrogen based on a selected
operating condition [215]. However, there are two reasons that the nitrogen was not
used in the surrogate fuel: (i) the chemical compounds considered were those having
above 5% weight percentages in the biocrude; and (ii) in general, it is very uncommon
for nitrogen to be in fuel. However, nitrogenated components in the fuel could be
another area for future research to explore. The behaviour of multi-component fuels is
more complicated than single-component fuels because of the potential for chemical
interactions. Though, these chemical compounds come from a relatively stable
microalgae HTL biocrude so these interactions in the surrogate fuel were presumed to
be realistic.
Chapter 6: Investigation of microalgae HTL fuel effects on diesel engine performance and exhaust emissions
using surrogate fuels 99
Selected palette for design fuel
Blend selected palette base
on design properties
Measure design properties
of surrogate fuel
Achieved target fuel
properties?
Y
Surrogate
fuel complete
Change selected
chemicals proportion
N
Design fuel
Select the design properties
and target
Measure and analysis physicochemical
properties of palette: chemical
composition, density, viscosity and HHV
Stop
Figure 6.8: Proposed roadmap for development of microalgae HTL surrogate fuels.
Figure 6.9: Percentage of chemical compound of a new microalgae HTL surrogate.
Aromatics20%
Cyclic ketone15%
Alkane45%
Alcohol10%
Aromatics FAME10%
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 100
The microalgae HTL surrogate fuel (100%) was blended with the reference
diesel at three different percentages: 10%, 20% and 50%.
Sur-10 Sur-20 Sur-50
Figure 6.10: Blended microalgae HTL surrogate for engine test.
6.3 MATERIALS AND METHODS
The experiments were conducted in the Biofuel Engine Research Facility
(BERF) at QUT with a EURO IIIA heavy-duty diesel engine using surrogate blends
and neat diesel fuel (100%). The engine was operated at a constant speed of 1500 rpm
(maximum torque speed) at four different loads: 25%, 50%, 75% and 100% of full
load. Maximum load at any engine speed depends on the type of fuel used, therefore
the maximum load for each fuel was determined when the engine was at full throttle
at 1500 rpm.
All experiments were conducted in a common-rail six-cylinder, turbo-charged
and after-cooled diesel engine with the specifications listed in Table 6.1. The engine
had a capacity of 5.9 L, maximum torque of 820 Nm at 1500 rpm and maximum power
of 162 kW at 2000 rpm. This engine was not fitted with any exhaust gas recirculation
(EGR). Each cylinder had four valves, two of them for inlet and two of them for
exhaust. The engine was coupled with a water-based dynamometer.
Diesel
Surrogate
Chapter 6: Investigation of microalgae HTL fuel effects on diesel engine performance and exhaust emissions
using surrogate fuels 101
Figure 6.11 shows the schematic of the experimental engine setup. Further detail
of the engine configuration and instruments can be found in Bodisco and Brown [221].
Table 6.1: Test engine specification.
Physicochemical properties of pure chemical compounds of surrogate fuel and
its blends are shown in Table 6.2 and Table 6.3 respectivey. The first row of Table 6.3
shows the name of the four different fuels 100D, 90D10S, 80D20S, and 50D50S
classified by the volume of each fuel. The Microalgae HTL surrogate was in colour
less with recognisable odour. The physicochemical properties of the reference diesel
and 100% surrogate fuel were experimentally measured. The properties of the blends,
including 90D10S, 80D20S, and 50D50S, were calculated proportionally based on the
neat fuel properties shown in Table 6.3 [3, 57]. Conversely, CN of the surrogate
chemical compound was found from published results, which are shown in Table 6.2.
CN for a few of the surrogate chemical compounds could not be found in the literature.
Therefore, an almost similar chemical compound for CN was used and is described
here. The CN for aromatic HC 1,2-dimethylbenzene is 8.3, which is part of the xylene
compound [222]. Xylene was used as a chemical compound of surrogate fuel, which
is a mixture of o-xylene, m-xylene, and p-xylene. The exact CN of xylene was
unknown. Likewise, the CN of cyclohexanone was unknown so the CN of
cyclopentanone, which is 10, was used instead. The CN for dihexyl phthalate was used
instead of dioctyl phthalate (DOP) due to an almost identical chemical structure [222].
Figure 6.11 shows a schematic diagram of the experimental set up for diesel-
engine performance and exhaust-emissions measurement. The engine performance
data, including in-cylinder pressure, diesel injection timing and degrees of crank angle
Model Cummins ISBe220 31
Cylinders 6 in-line
Capacity 5.9 L
Bore x stroke 102 x 120 (mm)
Maximum power 162 kW @ 2500 rpm
Maximum torque 820 Nm @ 1500 rpm
Compression ratio 17.3:1
Aspiration Turbocharged
Fuel injection High-pressure common rail
Dynamometer type Electronically-controlled water brake dynamometer
Emission standard Euro IIIA
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 102
rotation, were recorded. Indicated work (IW) was calculated by integrating a pressure
vs volume diagram using the trapezoid rule. Further detail of the engine performance
measurements can be found in Bodisco and Brown [221]. Different exhaust gas
measuring instruments, including DMS500, DustTrak (Model 8530), SABLE (CA-10)
and CAI 600, were used for emissions measurements. The DMS500 (Cambustion Ltd.)
is uniquely suited for a variety of diesel particulate filter applications. CAI 600 series
analysers were used to measure the raw exhaust gases CO, CO2, NO and NOx, and
Sable and DustTrak were used to measure diluted CO2 gas and particulate mass
respectively. Both DMS500 and DustTrak were used for measurement of PN and PM.
Further detail of the engine exhaust emission measurements can be found in Rahman
et al. [57]. All measurements were repeated three times, and the repeatability was
quantify by calculating the standard deviation and this is shown (Figure 21, 22, 24 26
and 28) as ±1σ standard deviation.
Table 6.2: Properties of diesel and surrogate chemical compounds.
Properties
Methods
Diesel
Chemical Groups
Aromatic Cyclic ketone
Alkane Alcohol Aromatic
FAME
Chemical compounds
Xylene Cyclopen-tanone
Undecane Butanol Dioctyl- pathalate
Surrogate comp- osition (% wt)
20 15 45 10 10
Density (kg/L)1 ASTM D4052 0.84 0.84 0.92 0.77 0.81 0.96
K. Viscosity (mm2/s)1
ASTM D240
2.66 1.39 1.70 1.89 2.57 27.40
HHV (MJ/kg)1 ASTM D240 45.64 42.41 34.09 46.24 36.2 35.7
LHV (MJ/kg) --- 43.95 40.48 32.14 43.09 33.43 33.70
Surface tension1 --- 26.77 27.44 29.89 25.17 25 30.55
Carbon (%wt.)2 --- 91.66 90.5 71.37 84.51 64.79 73.79
Hydrogen (%wt.)2 --- 8.34 9.5 9.59 15.49 13.61 9.81
Oxygen (%wt.)2 --- 0 0 19.04 0 21.59 16.4
C:H --- 10.99 9.52 7.44 5.45 4.76 7.52
Flash point (°C)3 ASTM D93 67.5 25 30 70 35 207
Cetane index ASTM D4737A
51.744 8.35 107 795 177 485
1- Measured at QUT, 2- Calculated, 3- Chemical certificate, 4- Caltex fuel certificate, 5-
Blend methods, 6- ASTM D613 (CFR), 7- Unknown methods.
Chapter 6: Investigation of microalgae HTL fuel effects on diesel engine performance and exhaust emissions
using surrogate fuels 103
Table 6.3: Properties of diesel, surrogate and surrogate blends.
Properties Methods 100D 100S 90D10S 80D20S 50D50S Biodiesel
Standard
ASTM
6751-12
Density(Kg/L)1 ASTM D4052 0.84 0.83 0.84 0.84 0.84 0.86-0.9
HHV(MJ/kg)1 ASTM D240 45.64 42.34 45.2 44.83 43.62 --
LHV(MJ/kg)2 -- 43.95 39.77 42.45 42.07 40.93 --
K. viscosity (mm2/s)2 ASTM D445 2.66 4.38 2.83 3.00 3.52 1.9-6.0
Lubricity (mm)3 IP 450 0.412 -- -- -- --
Carbon (% wt.)2 -- 87 80.69 85.59 85.04 83.41 --
Hydrogen (%wt.)2 -- 13 12.65 13.75 13.62 13.26 --
Oxygen (%wt.)2 -- 0 6.65 0.67 1.33 3.33 --
C:H2 -- 6.69 6.38 6.23 6.24 6.29 --
Flashpoint (°C)2 ASTM D93 68.66 65.2 67.27 67.04 66.35 130
Cetane index3 ASTM
D4737A
51.74 45.212 51.092 50.432 48.472 7 min
1- Measured at QUT, 2- Calculated, 3- Caltex fuel certificate
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 104
Compressed Air
SABLE CA-10Dust Track
Diesel Engine Exhaust emissions flow Diluted exhaust flow
CAI gas analyser
Engine control roomEngine room
DMS500
Figure 6.11: Schematic diagram of the engine exhaust measurement system used for
this study.
6.4 RESULTS AND DISCUSSION
This section describes the engine performance and exhaust emissions using
microalgae HTL surrogate blends, as well as comparisons of their individual
measurements. The engine performance parameters, including BP, IP, IMEP, BSFC,
ISFC, BTE, and ITE, in-cylinder pressure and volume, are presented in separate
Figures. The properties of microalgae HTL surrogate fuels were measured and
calculated and were found to be close to those of diesel fuel. It is generally accepted
that the fuel properties influence the fuel-spray characteristics, fuel evaporation, the
formation of fuel droplet size, distribution of fuel atoms and, therefore, the exhaust
emissions.
6.4.1 Engine performance
The indicated power (IP) of an engine is the power produced by the combustion
products on the piston in the cylinder. Conversely, the BP is the useful power at the
output shaft. The IP and BP variations with engine load are shown in Figure 6.12. It
was observed that both IP and BP linearly increased with increasing engine load for
Chapter 6: Investigation of microalgae HTL fuel effects on diesel engine performance and exhaust emissions
using surrogate fuels 105
the reference diesel and surrogate blends. The difference between the IP and BP
reduced as the load increased, indicating a reduction in friction power. This is
consistent with other research findings [218, 220]. On this engine, the maximum IP
for 100% of full load for reference diesel is 130 kW. A very small changes in either IP
or BP among the fuels were observed. This is most likely due to the close calorific
value of microalgae HTL surrogate blends compared to that of reference diesel.
Figure 6.12: IP and BP variation with IMEP for different fuels.
Figure 6.13 shows the BTE and BSFC, which are calculated using equations
(6.1) and (6.2), respectively. BTE can be defined as the BP of a heat engine as a
function of the thermal input from the fuel. BTE is used to measure how mechanically
efficient an engine is at converting the chemical energy of fuel to useful mechanical
energy [5]. It was observed that BTE reached a maximum (38%) at around 50% load
for all fuels. This is consistent with other published results [220, 221, 223]. . Compared
to diesel use of a surrogate blend results in a slight decrease in BTE for all engine loads
which is greatest for 50S50D. The reduction in BTE with surrogate blends is due to
the lower heating value of the surrogate blends.
BSFC is a measure of the fuel effectiveness of an engine that burns fuel and
produces power. It is typically used for comparing the efficiency of engines with
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 106
output power and represents the ratio between the rate of fuel consumption and the BP.
Compared to diesel use of a surrogate blend results in a slight increase in BSFC for all
engine loads which is greatest for 50S50D. The variation between BSFC for the
reference diesel and for the blends was in the range of 217–225 g/kWh across all loads.
Zare et al. [80] reported similar variation of results. It is revealed from Figure 6.13 that
BTE and BSFC have a reciprocal relationship. While BTE decreases with increasing
IMEP, BSFC increases with increasing engine load for reference diesel and their
blends.
𝐵𝑇𝐸 =𝐵𝑃∗100
Mf ∗ 𝐿𝐻𝑉 --------------------------------------------------- (6.1)
𝐵𝑆𝐹𝐶 =3600∗𝑀𝑓∗1000
BP ------------------------------------------ (6.2)
Where BTE in % and BSFC in g/kWh, BP in kW, Mf is the mass-flow rate of fuel in
kg/s, and LHV is the lower heating value of fuel in MJ/kg.
Figure 6.13: BTE and BSFC variation with IMEP for different fuels.
Chapter 6: Investigation of microalgae HTL fuel effects on diesel engine performance and exhaust emissions
using surrogate fuels 107
Figure 6.14: ITE and ISEC variation with IMEP for different fuels.
ISFC and ITE were calculated using equations (6.3) and (6.4). The ITE is a
dimensionless performance-measuring parameter, which gives an idea of the power
generated by the engine with respect to the heat supplied. As illustrated in Figure 6.14,
ITE was almost the same for all tested fuels. The ITE reduced gradually with an
increase in engine load for both blended fuels, which is consistent with other published
results [224]. On the other hand, ISFC results indicate that the fuel efficiency of the
engine is affected with respect to thrust output. Figure 6.14 also shows that ISFC
slightly decreased with increasing engine load but stayed almost the same for all tested
blends. This indicates that there was no change in the fuel efficiency when using
microalgae HTL surrogate blends compared to reference diesel fuels. This could be
due to the fuel’s heating value, surface tension and density, which are almost the same
as the reference diesel, as shown in Table 6.3.
𝐼𝑇𝐸 =𝐼𝑃∗100
𝑀𝑓∗𝐿𝐻𝑉 ------------------------------------------------- (6.3)
𝐼𝑆𝐹𝐶 =3600∗𝑀𝑓∗1000
IP ---------------------------------- (6.4)
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 108
To minimise the effect of cycle-to-cycle variations, the in-cylinder pressure data was
recorded for 750 consecutive cycles and the mean was taken to plot Figure 6.15 to
Figure 6.18. The peak in-cylinder pressure with the reference diesel was found to be
11 MPa, which is the highest among the fuels, while 50D50S produced the lowest.
Variation of in-cylinder pressure (P) with respect to the crank angle (CA) for different
fuels, including 90D10S, 80D20S, 50D50S, and 100D, are shown in Figure 6.15 and
Figure 6.16 for 100% and 50% load respectively. The lower in-cylinder pressure with
surrogate blends is due to lower energy content (HHV) of the fuel. Conversely, for
both loads (100% and 50%), the surrogate fuels showed lower pressure peaks than the
reference diesel. Both loads in Figure 6.16 showed two pressure peaks, one near the
TDC and the other in the expansion stroke for all fuels, and were dominant for 50%
load. The dominant pressure peak for 50% load at the expansion stroke needs further
investigation.
The in-cylinder volume is a function of the crank angle so that it is possible to relate
the cylinder pressure to cylinder volume, which is depicted in the PV diagram shown
in Figure 6.17 and Figure 6.18 for 100% and 50% of full load respectively. When the
piston is at bottom dead centre (BDC), the cylinder will have its largest volume. As
the piston moves up to the top dead centre (TDC), the volume is reduced to a minimum.
No significant variation in pressure was observed with respect to cylinder volume for
all blends, which is consistent with the pressure versus crank-angle curve. Combustion
resonance with a frequency of ~6000 Hz was observed in both Figure 6.17 and Figure
6.18. This resonance has been investigated in detail by Bodisco et al. [30].
Chapter 6: Investigation of microalgae HTL fuel effects on diesel engine performance and exhaust emissions
using surrogate fuels 109
Figure 6.15: Variation of pressure with crank angle for 100% load for different fuels.
Figure 6.16: Variation of pressure with crank angle for 50% load for different fuels.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 110
Figure 6.17: Variation of pressure with crank angle for 100% load for different fuels.
Figure 6.18: Variation of pressure with crank angle for 50% load for different fuels.
Chapter 6: Investigation of microalgae HTL fuel effects on diesel engine performance and exhaust emissions
using surrogate fuels 111
Figure 6.19 shows the peak pressure and rate of pressure rise versus engine load
for the four fuels. Although surrogate blends showed lower peak pressure, the
reduction was small. In regards to maximum pressure rise rate, compared to the
reference diesel, all surrogate blends showed a higher maximum pressure rise rate.
This could be due to the lower CN in the surrogate blends and warrants further
investigation. The highest peak pressure and boost pressure were found to be around
11,000 kPa and 245 kPa respectively for 50D50S, which may pose a concern for
engine vibration and wear (see Figure 6.20).
Figure 6.19: Effect of Microalgae HTL surrogate blended fuels on peak pressure and
rate of pressure rise.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 112
Figure 6.20: Effect of Microalgae HTL surrogate blended fuels on boost pressure.
6.4.2 Engine performance
In this section, engine exhaust emissions, including specific NOx, CO, PM and
PN, are discussed. The engine was operated at a maximum torque speed condition
(1500 rpm) with four different loads.
Gaseous emissions
Figure 6.21 and Figure 6.22 show NO2 and NOx emissions with respect to engine
load for the reference diesel and three surrogate blends. At low-load condition (25%),
the formation of NO2 emissions with surrogate blends was much higher than that at
high loads (50%, 75% and 100%), which could be due to pre-injection. This pre-
injection works through an engine management system (EMS) for low-load
conditions. Further research is therefore required to confirm the causes to higher NO2
emissions at low-load conditions. However, compared to the reference diesel, all
surrogate blends produced higher NOx emissions at all engine loads. Figure 6.24 shows
the percentage increase of NOx, which is approximately 15–20%, with respect to the
reference diesel. This is due to the oxygen percentage of surrogate blends, which is
consistent with the published literature [78, 81, 225]. Nabi et al. [220] reported that
Chapter 6: Investigation of microalgae HTL fuel effects on diesel engine performance and exhaust emissions
using surrogate fuels 113
higher NOx emissions resulted from fuel oxygen. The higher NOx emissions with
surrogate blends are associated with the higher maximum pressure rise rates (Figure
6.19) during the premixed combustion and lower CN, which is shown in Table 6.3. As
shown in Figure 6.21 and Figure 6.22, the percentage of normalised NO2 compared to
NOx is 4–5.5% for all tested fuels except for a 25% load of surrogate fuel.
Figure 6.21: Brake-specific nitrogen dioxide (NO2) emissions for four different load.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 114
Figure 6.22: Brake-specific nitrogen oxide (NOx) emissions for four different loads.
Figure 6.23: Percentage increases of NOx emissions compared to reference diesel.
25 50 75 100
Load (% of full load)
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5N
Ox (
g/k
Wh)
100D 90D10S 80D20S 50D50S
EURO-III
Chapter 6: Investigation of microalgae HTL fuel effects on diesel engine performance and exhaust emissions
using surrogate fuels 115
Figure 6.24: Brake-specific CO emissions for four different loads.
Figure 6.25: Percentage reduction of CO emissions compared to reference diesel.
The CO emission is one indication of the incomplete combustion of the air-fuel
mixture that takes part in the combustion chamber [226]. Diesel engines generally
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 116
produce low CO emissions as they usually run on a lean mixture [227]. It is important
to note that all surrogate blends reduced CO emissions compared to those of the
reference diesel at every loading condition. This can be seen in Figure 6.24. This is
due to the oxygen content of the fuel, which helps to complete combustion. [226]. A
maximum 45% reduction in CO emissions with surrogate blends was observed
compared to the reference diesel. Furthermore, the CO emissions among all fuels were
within the EURO IIIA standard limit (5 g/kWh) [82].
Particle emissions
Figure 6.26 illustrates particulate matter (PM) emissions using three surrogate
blends (90D10S, 80D20S and 50D50S) and the reference diesel (100D). Reductions
in PM emissions with microalgae HTL surrogate blends were obtained compared to
those with the reference diesel, which is shown Figure 6.27. Nabi et al. [220] and Zare
et al. [80] reported reduced PM emissions with oxygenated fuels. The literature has
revealed that the increases in surface tension improve fuel combustion, while reducing
NOx and PM emissions [82]. PM emissions are significantly affected by the fuelling
system, engine operating conditions and ambient conditions [223, 228]. However, the
relationship between PM and surface tension is not linear and surface tension is
possibly not the only factor to reduce PM emissions—there are other fuel properties
that could influence PM reductions [82]. The current investigations are consistent with
a number of previous studies [3, 5, 229]. It is interesting to note that the PM emissions
are significantly lower than the Euro IIIA standard for all tested fuels, which is shown
in Figure 6.27. Compared with the Euro IIIA standard, all three surrogate blends
showed remarkable reductions in PM emissions. Relative to the reference diesel, a
maximum of 88% PM reductions was observed with the surrogate blends.
Variations in the brake-specific PN emissions across the four different fuels at
four loading conditions are shown in Figure 6.28. For all loading conditions, surrogate
blends reduced PN emissions compared to those of the reference diesel (100D). At
medium- to high-load conditions, the reductions in PN emissions among the surrogate
blends were low compared with low-load conditions. The percentage reduction of PN
compared to the reference diesel is shown in Figure 6.29. The literature showed that
oxygenated fuels reduced PN emissions [5, 57, 230]. The current investigation
therefore supports the published literature [35, 38, 51].
Chapter 6: Investigation of microalgae HTL fuel effects on diesel engine performance and exhaust emissions
using surrogate fuels 117
Figure 6.26: Variation of brake-specific particulate mass for different loads.
Figure 6.27: Percentage of reduction of particulate mass emissions compared to
reference diesel.
25 50 75 100
Load (% of full load)
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
PM
(g
/kW
h)
100D 90D10S 80D20S 50D50S
EURO-III
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 118
Figure 6.28: Variation of brake-specific PN for four different loads.
Figure 6.29: Percentage reduction of PN emissions compared to reference diesel.
Chapter 6: Investigation of microalgae HTL fuel effects on diesel engine performance and exhaust emissions
using surrogate fuels 119
Based on the results discussed above, it can be concluded that microalgae HTL
surrogate blends performed well in terms of engine performance and exhaust
emissions. Most of the emissions using microalgae HTL surrogate blends were
reduced due to the similarity in their physical and chemical properties with biocrude.
However, all engine performance parameters showed insignificant change with
microalgae HTL surrogate blends due to the similarities in energy content with that of
the reference diesel.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 120
6.5 CONCLUSION
The objective of this study was to develop a microalgae surrogate using a pure
chemical compound of microalgae HTL biocrude that effectively approximated the
chemical composition, density, viscosity, HHV, and surface tension of the reference
diesel. Engine performance and exhaust emissions were also investigated with
microalgae surrogate blends in a six-cylinder fully-instrumented turbo-charged diesel
engine.
The aromatics, cyclic ketone, alkane, alcohol, and aromatic FAME chemical
groups were used to produce target surrogate fuel by HTL microalgae biocrude. Each
chemical compound of surrogate fuel had its physicochemical properties controlled by
the target fuel. The interaction between each chemical compound was already
quantified because those chemical compounds were part of the same microalgae
biocrude.
No significant changes in engine performance were observed with HTL
surrogate blends when compared to those of the reference diesel.
All major emissions, including PM, PN and CO, were reduced significantly with
the surrogate blends, with increasing in NOx emission.
When compared with the reference diesel, a maximum of approximately 88%
and 58% reductions in PM emissions were obtained with the surrogate blends at 25%
and 100% of full load. Maximum reductions in PN emissions with the surrogate blends
were found at lower loads, but minimum reductions were found at medium and higher
loads.
NOx emissions with surrogate blends were higher compared to those of the
reference diesel. Exhaust after treatment, including exhaust gas recirculation technique
or changing the injection timing, could also reduce NOx emissions with surrogate
blends and thus needs more investigation.
Chapter 6: Investigation of microalgae HTL fuel effects on diesel engine performance and exhaust emissions
using surrogate fuels 121
6.6 ACKNOWLEDGEMENTS
This research was supported by the Australian Research Council’s Linkage
Projects funding scheme (project number LP110200158). The authors would also like
to acknowledge Mr. Andrew Elder from DynoLog Dynamometer Pty Ltd and Mr. Noel
Hartnett for their laboratory assistance, Dr. Md Jahirul Islam and Dr. Svetlana
Stevanovic for their guidance, and Mohammad Jafari for assistance with measuring
instruments.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 122
Chapter 7: Investigation of diesel engine performance and exhaust emissions using tyre oil 123
Chapter 7: Investigation of diesel engine
performance and exhaust
emissions using tyre oil
Farhad M. Hossain1,2*, Thomas J. Rainey1,2, Timothy Bodisco3, Trevor Bayley4,
Denis Randall4, Zoran Ristovski1,2, Richard J. Brown1,2
1Biofuel Engine Research Facility, Queensland University of Technology (QUT), QLD 4000,
Australia 2School of Chemistry, Physics and Mechanical Engineering, QUT, QLD 4000 Australia 3School of Engineering, Deakin University, Waurn Ponds, Victoria 3217, Australia 4Green Distillation Technologies (GDT) Corporation Limited, Victoria 3142, Australia
Statement of contribution of Co-Authors for this publication
The authors listed in the table below have certified that:
1. they meet the criteria for authorship in that they have participated in the conception, execution, or
interpretation, of at least that part of the publication in their field of expertise;
2. they take public responsibility for their part of the publication, except for the responsible author who
accepts overall responsibility for the publication;
3. there are no other authors of the publication according to these criteria;
4. potential conflicts of interest have been disclosed to (a) granting bodies, (b) the editor or publisher of
journals or other publications, and (c) the head of the responsible academic unit, and
5. they agree to the use of the publication in the student’s thesis and its publication on the Australasian
Research Online database consistent with any limitations set by publisher requirements.
Title and status: Investigation of diesel engine performance and exhaust emissions
using tyre oil (under review)
Contributor Statement of contribution
Md Farhad Hossain Candidate
Conducted the experimental work, performed data analysis, interpreted
the results, wrote the manuscript and acted as the corresponding author.
Signature
Date
Richard J. Brown Principal Supervisor
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 124
Professor Richard Brown is a mechanical engineer, he is a leading
expert in thermodynamics and environmental fluid mechanics,
particularly in relation to internal combustion engine performance and
emissions.
Aided the design of the experiment, conducted the experiments,
interpreted the results, discussed and edited the manuscript.
Thomas J. Rainey Dr Thomas Rainey has 15 years of industrial and research experience
in biomass processing particularly in pulp and paper and sugar
processing. His research focuses on bioenergy and related value-added
products.
Design concept of fuel properties measurements and edited the
manuscript as an associate supervisor.
Timothy Bodisco Dr Timothy Bodisco has been working as a Lecturer in the Department
of Mechanical Engineering at Deakin University. He has extensive
experience with engine experimental data analysis.
Dr Bodisco assisted with analyses of in-cylinder data using his own
matlab code and edited the manuscript.
Trevor Bayley Trevor Bayley has been working as a Chief Operating Officer (COO)
of GDT. Trevor Bayley and his company, Professor Richard Brown
and I have been working collaboratively.
Mr Bayley provided tyre oil for testing in the diesel engine.
Denis Randall Denis Randall is an inventor of GDT and is currently a GDT Technical
Director.
Zoran Ristovski Professor Zoran Ristovski is a physicist who works at Queensland
University of Technology as one of the leading researchers on vehicle
emissions with a special focus on particulate vehicle emissions.
Professor Zoran Ristovski designed and performed fuel properties
related to engine exhaust emissions and reviewed the manuscript.
Chapter 7: Investigation of diesel engine performance and exhaust emissions using tyre oil 125
Principal Supervisor Confirmation
I have sighted email or other correspondence from all Co-authors confirming their certifying
authorship.
Professor Richard J. Brown
Name Signature Date
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 126
Abstract:
This study investigates diesel engine performance and exhaust emissions using
tyre oil as an alternative fuel. There are approximately 20 million tons of end-of-life
tyres (ELTs) in the world today. In a novel process, Green Distillation Technologies
Corportation Ltd (GDT) converts whole ELTs into carbon, steel, and tyre oil. The
physiochemical properties of the tyre oil are similar to diesel fuel and the fuel is
miscible with diesel in any blended ratio. An engine experiment was conducted on a
EURO IIIA diesel engine at the Biofuel Engine Research Facility (BERF) at
Queensland University of Technology (QUT). All experiments were performed at
constant speed and four different engine loads. Two blends (10% and 20%) of tyre oil
were compared to reference diesel fuel. Exhaust emissions, including gaseous
emissions, particulate matter (PM) and particle count (PN), were investigated. The
results found significant changes, NOx emissions were reduced by approximately 30%
for both the 10% and 20% tyre oil blends when compared to the reference diesel fuel.
Other exhaust emissions, including PM and PN, were reduced significantly by 35-60%
and 5-20%, respectively, for both tyre oil blends. The only exception was the result for
CO, which showed an increase of approximately 2–3% compared to the reference
diesel, although not at a 25% load. Small changes were found with the tyre oil blends
with respect to engine performance parameters, including brake power (BP), brake
mean effective pressure (BMEP) and brake thermal efficiency (BTE). The engine
remained compliant with its EURO IIIA certification during the use of the tyre oil
blends.
Keywords: Tyre oil, diesel engine, emissions, pyrolysis, destination.
Chapter 7: Investigation of diesel engine performance and exhaust emissions using tyre oil 127
7.1 INTRODUCTION
Exhaust emissions regulations are becoming increasingly strict, globally.
However, the maximum exhaust emissions level for each country varies despite the
emissions legislation [231]. Diesel engine exhaust emissions may be controlled in
three ways: through engine modification, exhaust gas after-treatments or by using
alternatives to diesel fuel [232]. Engine manufacturing industries and researchers are
actively seeking alternative fuels for diesel engines that can reduce exhaust emissions.
Researchers are also trying to uncover reliable and efficient alternative feedstocks for
renewable fuels, including biomass feedstocks: corn, jatropha [233], palm oil [234],
mahua [235] and lignocellusic biomass [236], and non-biomass feedstocks, such as:
municipal waste and end-of-life tyres (ELTs) [24, 133, 166]. Unfortunately, the
majority are not able to be produced on a large enough scale owing to high production
costs. Many are also unsuitable for use in current diesel engines due to their
physiochemical properties.
There is a growing problem concerning ELTs disposal, globally [24]. Most
people are aware that ELTs are a significant environmental hazard, but few know the
extent of the mass that is generated each year. It has been reported that each year over
1 billion ELTs are generated worldwide, a number expected to increase to 1.5 billion
(or 20 million tons) by 2020, which represents a significant problem in terms of waste
disposal [13, 24]. These ELTs sometimes finish up in dumps, either legally or
illegally. One such tyre dump in the US has many millions of tyres, while one in the
Middle East is so vast that it can be seen from space. It has been reported that
Australians generate over 23 million ELTs, or 51 million equivalent passenger units
(EPU), each year [25]. A site in Stawell, Victoria, Australia contains an estimated 10
million old tyres. Local media have stated that if it caught fire, the local township
would be uninhabitable for 35 years [18]. Therefore, ELTs to fuel technology offers a
very promising solution for both issues [24].
ELTs are an organic waste from which useful energy in the form of liquid, gas
or solid can be derived. The calorific value of rubber from tyres is 35-40 MJ/kg, so
vehicle tyres appear very promising as a feedstock for fuel production [24, 26].
Australian Green Distillation Technologies (GDT) has invented a technique to produce
an alternative to diesel fuel from ELTs [18]. The technology reduces the whole tyres
to their original constituents, which are carbon, steel, and tyre oil [18].
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 128
The literature shows that tyre pyrolysis oil (TPO) has a lower cetane number
(CN) compared to diesel fuel [160, 237]. Some tyre pyrolysis oils use a cetane
improver such as ethers, diethyl ether, nitrides, amines, in the blend for their engine
experimental research [138]. Vihar et al. [24] tested TPO with and without an
intercooler to investigate the effect of the intake air temperature in an engine
turbocharged. They found a significant change in exhaust emissions, including
nitrogen oxide (NOx), carbon monoxide (CO) and total hydrocarbon (THC) when
compared with reference diesel fuels. Tudu et al. [138, 166] tested TPO in a diesel
engine as a blend with diesel fuel. They found that increasing the percentage of TPO
in the blend decreased NOx, but the opposite result was found for CO emissions [138].
In this research the tyre oil properties were tested and analysed before engine
experiments were conducted at Queensland University of Technology (QUT). Many
properties of tyre oil were found to be similar to diesel fuel, particularly CN, higher-
heating value (HHV), and density. To the best of the authors’ knowledge, only a
limited number of experiments investigating the effect of TPO as an alternative fuel
have been performed on a common-rail multi-cylinder turbo-charged (TC) engine[18].
The objectives of this study were to comparatively investigate diesel engine
performance and exhaust emissions with tyre oil blends without any cetane improver
or engine modification. The significance of this research is to determine the thermal
efficiency and exhaust emissions of this new innovative tyre oil in a commercial diesel
engine and establish a non-conventional fuel application in a regular engine without
modification. The performance of the engine output is presented in terms of in-cylinder
pressure, brake power (BP), brake mean effective pressure (BMEP), brake thermal
efficiency (BTE) and brake-specific fuel consumption (BSFC). Gaseous emissions of
nitrogen dioxide (NO2), nitrogen oxide (NOx), carbon monoxide (CO), particulate
matter (PM) and particulate number (PN) were measured and compared among the
tested fuels.
7.2 FUEL PRODUCTION AND PREPARATION
The GDT process for ELTs produces tyre oil, carbon and steel. The process emits
minimal emissions because most gases released by tyre processing are re-treated and
burnt to supply process heat. Many conversion technologies have been developed to
convert various feedstocks into fuels. Thermochemical conversion processes involve
Chapter 7: Investigation of diesel engine performance and exhaust emissions using tyre oil 129
pyrolysis and hydrothermal liquefaction that have been used for transforming many
feedstocks into fuels [132]. Thermochemical conversion processes use high
temperatures with or without the presence of oxygen to cause structural degradation.
Such technology has drawn much interest because it can directly produce liquid fuels
[36]. The hydrothermal liquefaction process is mainly used to convert wet feedstocks
into liquid fuels [136]. On the other hand, the pyrolysis process uses dry feedstock as
the raw materials to convert to liquid fuels. There are two tyres of feedstocks based on
water contains, those are contained water called wet feedstocks and those are not
contained water or remove water from feedstocks called dry feedstocks. Pyrolysis
processes depend on factors such as temperature, material size, and time [68,
150].However, as far as the authors can ascertain, these processes are generally not
economically viable to produce fuel from ELTs.
GDT has achieved a technological breakthrough by successfully and
commercially recycling end-of-life car and truck/bus tyres into the valuable
commodities of oil, carbon, and steel. ELTs are a blight on the environment because
until now, no means have been found to effectively and profitably recycle them [18].
However, using a technique known as destructive distillation, GDT can turn this
wasted resource and environmental hazard into three high-demand valuable raw
materials: tyre oil, carbon, and steel. Table 7.1 shows the GDT-recycled product and
quantity based on tyre types. The process is emissions free and part of this tyre oil is
used as fuel for the burner which is a heat source for the production process.
Table 7.1: GDT recycled product and quantity based on tyre types [18].
Types of Tyre Unit
(mass)
Kg
Recycled product in weight
Tyre Oil (Kg) Carbon
(Kg)
Steel
(Kg)
Car tyre 10 3.5 – 4.0 3.5 – 4.0 1.5 – 2.0
Truck tyre 70 28.0 – 30.0 28 – 30.0 11.0 – 14.0
Giant mining tyre 7,000 2,800 – 3,000 2,800 – 3,000 1,000 -1,400
7.3 MATERIALS AND METHODS
The experiments were conducted at QUT in the Biofuel Engine Research Facility
(BERF) using two different blends. Two blends were prepared using tyre oil: 10% and
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 130
20% by volume with diesel. The engine was operated at a consistent speed of 1500
rpm (maximum torque speed), at four different loads 25%, 50%, 75% and 100%.
Maximum load at any engine speed depends upon type of fuel used, therefore the
maximum load for each fuel was determined when the engine was 1500 rpm.
This study used a Cummins EURO IIIA common-rail six-cylinder, turbo-
charged and after-cooled diesel engine with the specifications shown in
Table 7.2. The engine has a capacity of
5.9 L, maximum torque of 820 Nm at 1500 rpm and maximum power of 162 kW at
2000 rpm. The engine can be operated with a dual fuel mode and was coupled with a
water-flow dynamometer for loading the engine at different loads and speeds. The
software electronically controls the dynamometer. Figure 7.1 shows the schematic of
the experimental engine setup.
Table 7.2: Test-engine specifications.
The set of fuels used in the experiments is shown in Table 7.3. The first row
represents the name of the four different fuels—100D, 100T, 90D10T, and
80D20T.Classified by the volume of each fuel. The important physicochemical
properties of the fuels were experimentally measured. The blend properties were
calculated based on pure fuel properties that are shown in Table 7.3 [3, 57]. The
properties of tyre oil were tested and were found to be similar to diesel fuel when
comparing HHV, viscosity, and density. Regarding elemental composition, carbon and
hydrogen contents for tyre oil compare well with those for diesel fuel, while the sulfur
contents for tyre oil remarkably high compare to diesel. However, before conducting
the experimental studies, a careful fuel analysis was carried out. It is broadly accepted
that fuel properties influence the fuel-spray characteristics, fuel evaporation, the
Model Cummins ISBe220 31
Cylinders 6 in-line
Capacity 5.9 L
Bore x stroke 102 x 120 (mm)
Maximum power 162 kW @ 2500 rpm
Maximum torque 820 Nm @ 1500 rpm
Compression ratio 17.3:1
Aspiration Turbocharged
Fuel injection High-pressure common rail
Dynamometer type Electronically-controlled water brake dynamometer
Emission standard Euro IIIA
Chapter 7: Investigation of diesel engine performance and exhaust emissions using tyre oil 131
formation of fuel droplet size, distribution of fuel atoms and, therefore, the exhaust
emissions. These features depend on the physiochemical properties of the fuel.
Figure 7.1 shows a schematic of the engine performance and exhaust emission
measurements. The engine operating data load, mass flow rate of fuel and air, and
speed, were logged using Dynalog software. Further details of the engine performance
measurements can be found in Bodisco and Brown [221]. Various instruments were
used for exhaust emission measurements including DMS500, DustTrack (Model
8530), SABLE (CA-10) and CAI 600. The Cambustion DMS500 is uniquely suited
for a variety of diesel particulate filter applications. CAI 600 series analysers were
used to measure raw exhaust gasses CO, CO2, NO and NOx, and Sable and DustTrack
used to measure diluted CO2 gas and particulate mass respectively. Further details of
the engine exhaust emission measurements can be found in Rahman et al. [57].
Table 7.3: Properties of diesel, tyre oil and their blends.
Properties Methods 100D 100T 90D10T 80D20T
Density(Kg/L)1,2 ASTM D4052 0.844 0.847 0.845 0.845
HHV(MJ/kg)1,2 ASTM D240 45.64 42.28 45.31 44.97
LHV(MJ/kg) -- 43.95 39.05 43.46 42.97
K. viscosity (mm2/s)1,2 ASTM D445 2.66 3.43 2.74 2.81
Lubricity (mm)1,2 IP 450 0.412 0.289 0.339 0.387
Carbon (% wt.)3 -- 87 84.1 86.71 86.42
Hydrogen (%wt.)3 -- 13 15.9 13.29 13.58
C:H3 -- 6.69 5.29 6.52 6.36
Sulfur (ppm) ASTM D7039 7.2 3500 356.46 705.76
Ash content (mg/kg)1,2 ASTM D482 0.01 0.001 0.0091 0.0082
Flashpoint (°C)1,2 ASTM D93 68.66 97 71.49 74.32
Cetane index1,2 ASTM D4737A 51.74 51.7 51.74 51.73
1- Caltex fuel certificate, 2- Tyre oil certificate, 3- Calculated
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 132
Compressed Air
SABLE CA-10Dust Track
Diesel Engine Exhaust emissions flow Diluted exhaust flow
CAI gas analyser
Engine control roomEngine room
DMS500
Figure 7.1: Schematic diagram of the engine exhaust measurement system used for
this study.
7.4 RESULTS AND DISCUSSION
This section describes the engine performance and exhaust emissions using tyre
oil and blends of diesel and tyre oil, as well as a comparison of individual
measurements. The engine performance measurements include BP, IP, IMEP, BSFC,
ISFC, BTE, and ITE. In-cylinder pressure versus crank angle and volume are presented
in separate figures, for all tested fuels. The results with tyre oil blends were compared
to some other published results [5]. The research showed no significant difference in
the performance of the BP, BSFC and BTE parameters between the tyre oil blends and
the reference diesel tested in the same engine [220, 223]. However, the exhaust
emissions, including NO2, NOx, CO, PM and PN, were significantly different using
neat tyre oil when compared to other experimental results [24, 138, 166]. Ideally, the
results from both the diesel and the tyre oil blends engine performance and emissions
should be compared with those of tyre pyrolysis oil produced from other techniques
[24, 138].
Chapter 7: Investigation of diesel engine performance and exhaust emissions using tyre oil 133
7.4.1 Engine performance
The indicated power (IP) of an engine is the power produced in the cylinder.
Conversely, the BP is the useful power at the output shaft. The IP and BP variation
with engine load are shown in Figure 7.2. The difference between the IP and BP
reduced as load increased, indicating a reduction in power. This is consistent with the
findings of other researchers [5, 80, 218, 220, 238]. The maximum IP output at 100%
of full load for diesel was approximately 130 kW. There was no significant change
found in power between 100D, 90D10T and 80D20T fuels for either the diesel or
blends. This is most likely due to the relatively high calorific value of tyre oil, which
is approximately 42.8 MJ/kg and compares well with that of diesel (45.64 MJ/kg).
Figure 7.2: IP and BP variation with IMEP for three different fuels.
Figure 7.3 shows the BTE and BSFC, which are calculated using equations (7.1)
and (7.2), respectively. BTE can be defined as ratio of brake power to fuel power. BTE
is used to define how mechanically efficient the engine is at converting chemical
energy from the fuel to useful mechanical energy [5]. In this study, BTE reached its
maximum at around 0.95 MPa of IMEP for all fuels, which is about 38%. Zare et al.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 134
[80] and Nabi et al. [223] conducted experiments with the same engine using waste
cooking oil and reported similar results. The BTE was almost constant after 1.1 MPa
of IMEP. There were no significant changes found between the diesel and their blends.
This may be due to the similarity between fuel properties including HHV, CN and
density of the fuel, which were shown in Table 7.3.
The BSFC is a measure of the fuel effectiveness of the engine. It is typically used
for comparing the efficiency of engines with output power. However, as shown in
Figure 7.3, there were a very small change (about 1-2%) in BSFC with respect to load
among the diesel and tyre oil blends. The BSFC for diesel and the blends ranged
between 217–225 g/kWh for all load conditions. As depicted in Figure 7.3, while BTE
decreased with increased IMEP, BSFC increased with increased IMEP for diesel and
their blends. A similar observation was made by Islam et al. [3] and Nabi et al. [5].
Therefore, it can be said that an inverse relationship was found between BTE and
BSFC.
𝐵𝑇𝐸 =𝐵𝑃∗100
Mf ∗ 𝐿𝐻𝑉 -------------------------------------------------- (7.1)
𝐵𝑆𝐹𝐶 =3600∗𝑀𝑓∗1000
BP ------------------------------------------------- (7.2)
Where, BTE in % and BSFC in g/kWh, BP in kW, Mf is the mass flow rate of fuel in
kg/s, and LHV is the lower heating value of fuel in MJ/kg.
Chapter 7: Investigation of diesel engine performance and exhaust emissions using tyre oil 135
Figure 7.3: BTE and BSFC variation with IMEP for three different fuels.
Figure 7.4: ITE and ISEC variation with IMEP for three different fuels.
The indicated thermal efficiency (ITE) and indicated specific fuel consumption
(ISFC) were calculated using equations (7.3) and (7.4). As Figure 7.4 shows, ITE had
almost the same variation for all tested fuels with load. The ITE reduced gradually
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 136
with increasing engine load for both blended fuels, which is consistent with published
results [224]. On the other hand, ISFC indicated that the fuel efficiency of the engine
was affected with respect to thrust output. Figure 7.4 also shows that ISFC slightly
increased with increasing engine load but was almost the same for both blends. It can
be concluded that there was no change in fuel efficiency when using tyre-oil blends,
compared to diesel fuels.
𝐼𝑇𝐸 =𝐼𝑃∗100
𝑀𝑓∗𝐿𝐻𝑉 ---------------------------------------- (7.3)
𝐼𝑆𝐹𝐶 =3600∗𝑀𝑓∗1000
IP ------------------------------------ (7.4)
The slope of the pressure versus crank-angle curve gives an approximate value
for the start of combustion [239]. Variation of in-cylinder pressure (P) with respect to
the crank angle (CA) for different fuels90D10T, 80D20T, and 100Dis shown in Figure
7.5 and Figure 7.6 for 100% and 50% loads respectively. To minimise the effect of
cycle-to-cycle variations, the in-cylinder pressure data were recorded for 750
consecutive cycles and a mean cycle determined to plot Figure 7.5. The maximum
pressure was found for reference diesel fuel among all tested fuels, which was
approximately 11 MPa whereas this is the minimum for 80D20T blends. The peak
pressure of the cylinder reduced gradually as the load decreased for all tested fuels.
Furthermore, there was a small reduction 3-5% in peak pressure corresponding to
crank angle for the diesel and tyre-oil blends. This may be due to the difference in
HHV between diesel and tyre oil. The amount of heat generated in the cylinder is
related to C: H ratio, which is almost the same for diesel and tyre-oil blends. The C:H
ratio for 100D, 90D10T and 80D20T are 6.69, 6.52 and 6.36, respectively. This C:H
ratio, HHV and CN may be the reason for a small variation pressure curve. However,
it was observed cylinder peak pressure decrease with increases blend ratios and as a
decrease in load reduced the differences in cylinder pressure.
Chapter 7: Investigation of diesel engine performance and exhaust emissions using tyre oil 137
Figure 7.5: Variation of cylinder pressure with crank angle at 100% load for three
different fuels.
Figure 7.6: Variation of cylinder pressure with crank angle at 50% load for three
different fuels.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 138
The real engine cycle of a CI four-stroke engine can be presented by plotting the
pressure vs volume data extracted from in-cylinder pressure data. The in-cylinder
volume is a function of the crank angle so that it is possible to relate the cylinder
pressure to cylinder volume which constructs a PV diagram as shown in Figure 7.7 for
and Figure 7.8 for 100% and 50% of full load respectively. Further detail of the PV
curve can be found in appendix D. When the piston is at bottom dead center (BDC),
the cylinder will have its largest volume. As the piston moves up the cylinder, the
volume is reduced. At the top dead center (TDC) the cylinder is at its minimum
volume. From Figure 7.7 it can be seen that the peak pressure is consistently high for
diesel. This is due to the heat of combustion in the cylinder.
Figure 7.7: Variation of cylinder pressure with volume at 100% load for three
different fuels.
Chapter 7: Investigation of diesel engine performance and exhaust emissions using tyre oil 139
Figure 7.8: Variation of cylinder pressure with volume at 50% load for three
different fuels.
Peak cylinder pressure is the maximum in-cylinder pressure achieved during the
combustion process. The cylinder pressure is important because its relationship to
work. Figure 7.9 shows the peak pressure and rate of pressure rise of the cylinder
compared to the IMEP curve. There were no changes in peak pressure for different
fuels except at the maximum IMEP, for peak pressure. The rate of maximum pressure
rise was the same for the three different fuels in the same operating conditions. Figure
7.9 shows that the variation of maximum pressure rise curves was insignificant for all
tested loads except at a low IMEP. However, the rate of the rise in pressure was almost
the same for both tyre-oil blends. The only difference was with the reference diesel
fuel. The reason for the high level of maximum pressure rise for the tyre oil blend at
load are not clear at this stage. However, this may be important for interpreting NOx
emissions as it has normally been observed that increases in the maximum rate of
pressure rise are often associated with increases in NOx concentration, which has not
been found here. It may also have been caused by the physiochemical properties of
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 140
the tyre oil. This is an important avenue to investigate further in future. The highest
peak pressure was found at approximately 11000 kPa.
Figure 7.9: Effect of tyre oil on peak pressure.
7.4.2 Engine exhaust emissions
This section discusses engine exhaust emissions, including NOx, CO, PM and
PN, were measured and can be seen in the following Figures. The engine operated at
a constant RPM. Four loads tested with 100% corresponding to maximum torque (820
Nm) and reducing down to 25% load. All the emissions data were recorded at stable
and specific engine loads.
NOx emissions
The brake specific NOx formation in diesel engines is reportedly influenced by:
ignition delay, combustion temperature, compression ratio, CN and oxygen in the fuels
[5, 166, 240]. The variation of NO2 and NOx with load for the tested fuels are shown
in Figure 7.10 and Figure 7.11. It is also observed from both figures that about 5-10%
NO2 were produced compare to NOx. The two key factors predominantly affecting the
formation of the NOx emission in a diesel engine are the combustion temperature and
the ignition delay. At a constant power output, a maximum of 30% reduction in NOx
Chapter 7: Investigation of diesel engine performance and exhaust emissions using tyre oil 141
was found for GDT-tyre-oil blends, compared to diesel fuel. The parameters affecting
the formation of oxides of NOx in a diesel engine are the in-cylinder combustion
temperature, duration, higher compression ratio, engine operating speed,
physiochemical properties of fuel including CN, oxygen content etc. [13, 24, 138,
205]. There is no single explanation why NOx emissions change between fuels, rather
these emissions depend on a number of factors. However, in this case it is clear that
CN is not a factor in the observed NOx change since it is almost identical for both
diesel and tyre oil, (51.74 and 51.7, respectively).”
However, need further research to find out for that. Tudu et al. [166] reported
lower NOx emissions with increased tyre oil and diesel blends. It was reported by Frigo
et al. [237] that nitrogen oxide reduces as the volume percentage of the tyre pyrolysis
oil (TPO) rises in the mixture. The current investigation supports those similar studies
[80, 81, 138, 220]. The NOx results for all of all the tested fuels were lower when
compared to the EURO IIIA a standard 3.81 g/kWh.
CO emissions
The variation of CO with load for all tested fuels is shown in Figure 7.12. The
CO exhaust emissions are one indicator of incomplete combustion of the air-fuel
mixture that occurs in the combustion chamber [138, 237]. Diesel engines generally
produce low CO emissions as they run on a lean mixture. As shown in Figure 7.12,
there was no consistent increase or decrease of CO with the increase of engine load..
The maximum change of CO emissions was found at 25% load for both of the blended
fuels. Two important factors predominantly affect the formation of the CO in diesel
engine: incomplete combustion and air-fuel ratio. At low load operation condition this
may be due to a lean mixture at a low engine load operation.
The experimental results show that CO exhaust emissions change according to
the percentage of tyre-oil in the blends when compared to the reference diesel. Similar
results have also been reported in other published studies [145, 237, 241]. However,
the result for CO among all the tested fuels was within the EURO IIIA—a standard
limit of 5.0 g/kWh. CO emissions could be reduced using oxygenated fuel as an
additive with diesel and tyre-oil blends [220, 229].
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 142
Figure 7.10: Brake-specific NO2 emissions for four different loads.
Figure 7.11: Brake-specific NOx emissions for four different loads.
Chapter 7: Investigation of diesel engine performance and exhaust emissions using tyre oil 143
Figure 7.12: Brake-specific CO emissions for four different loads.
Particulate mass emissions
Figure 7.13 shows the results for particulate mass (PM) emitted by the engine
using the following fuels: 100D, 90D10T and 80D20T. There were significant
decreases in particulate mass emissions between the diesel and tyre-oil blends. The
CN number of tyre oil was 51.7, very similar to diesel. Increases in CN improve fuel
combustion, while reducing NOx and PM emissions. However, the relationship
between PM and CN is not linear and there are other properties, aside from CN, that
may influence PM. The results are consistent with a number of studies conducted
previously [3, 5, 229]. The PM reduction was more than 35% for both 10% and 20%
blends when compared to diesel. Finally, it was found that PM emissions for all the
tested fuels was low when compared to the EURO IIIA standard of 0.3.
NOx and PM have often been observed to have an inverse relationship. This is
generally most evident for a constant fuel operated in an engine with varying RPM and
loads. Comparisons of NOx and PM in Figures 11 and 13 did not show the above
simple trend most likely due to fuels of very different compositions (eg diesel and tyre
oil) increasing the complexity of the NOx – PM trade off mediated by cylinder
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 144
temperature, especially in the combustion zone. While the conventional NOx - PM has
been observed for comparisons of diesel and renewable fuels many researchers have
not observed that trend [34, 87, 116, 205, 242, 243].
Particulate number emissions
Variation of the brake specific PN with loads for different fuels is shown in
Figure 7.14. The maximum amount of PN was for the reference diesel fuel, which was
reduced in both 10% and 20% tyre oil blends. It can be seen from that the PN reduced
gradually according to the percentage of tyre oil in the blend. It can also be seen that
PN emissions were high at 25% of full load for each of the fuels. The percentage of
change of PN for blended fuel varied between 5-20% compared to diesel, which was
high at its low load condition. In this experiment, no oxygenated compounds were
used, so the results for PN are not influenced because of this. It was also observed that
the physical properties of tyre oil were similar to diesel, so it seems unlikely that PN
was influenced by this. The reduction of PN may be due to chemical properties of the
tyre oil such as chemical composition and structure. To the authors’ knowledge, the
measurement of PN with tyre oil is new and it is important to investigate further to
understand how PN changes with tyre oil.
Chapter 7: Investigation of diesel engine performance and exhaust emissions using tyre oil 145
Figure 7.13: Variation of brake-specific PM emissions for different loads.
Figure 7.14: Variation of brake-specific PN emissions for four different loads.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 146
7.5 CONCLUSION
In this study, diesel engine performance and exhaust emissions were measured
with 10% and 20% (by volume) tyre oil blends. The properties of the tyre oil were
measured and compared with the reference diesel. There was a small change found in
engine performance using tyre oil blends when compared to diesel, which may be due
to the energy content of the blends. Conversely, the brake-specific exhaust emissions
of NO2, NOx, CO, PM, and PN were measured and significant changes were found.
The brake-specific NOx decreased by 30% with tyre oil blends compared to the
reference diesel fuel. However, brake-specific emissions of CO increased with the
amount of tyre oil blended. PM and PN also reduced within the experiment. The PM
reduced by more than one third for tyre oil blends compared to diesel fuel. Tyre oil
properties, especially CN, HHV and density, were almost the same as diesel and there
was no separation found in the blends, which may be the reason for these results. The
results are very encouraging for the future use of tyre oil a blended alternative fuel,
like 10% ethanol (E10) for diesel engines. E10 is used as an alternative for petrol
engine. However, tests including aging, reliability, and durability need to be conducted
first.
Chapter 7: Investigation of diesel engine performance and exhaust emissions using tyre oil 147
7.6 ACKNOWLEDGEMENTS
This research was supported by the Australian Department of Industry,
Innovation and Science funded project (project number ICG000077). The author
would like to acknowledge Dr. Md Mostafizur Rahman for assistance with reviewing
this manuscript and would like to special thanks to Noel Hartnett for his help to
conduct experiments. The author would like to extend my great thanks to Niki
Widdowson, and Dennis Rutzou for their help in the waste-tyre oil project.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 148
Chapter 8: Conclusions and Recommendations 149
Chapter 8: Conclusions and
Recommendations
8.1 CONCLUSION
The research presented in this thesis aimed to investigate wet microalgae and
waste tyre as potential feedstock for alternative fuel using HTL and pyrolysis as a
thermochemical process. The particular focus with both fuels was on their
physicochemical properties and use in a CI engine. Microalgae HTL biocrude is not
suitable for use in a CI engine directly due to its physicochemical properties.
Consequently, a new surrogate fuel was developed based on the microalgae HTL
biocrude chemical compound and tested in a CI engine. Conversely, waste-tyre oil was
suitable for use directly as a blend in the engine test.
This project has filled a significant gap in the field of alternative fuel research,
including research into methods of reducing waste tyres from the environment. A
careful investigation of microalgae HTL surrogate and waste-tyre oil performance in
a CI engine and their emission characteristics have contributed significantly to the
existing literature.
8.1.1 Selection for feedstock
Feedstock selection is one of the most important steps to solve real-world
problems because the availability of the feedstock depends on large-scale production.
Microalgae have recently received a lot of attention in the production of biofuel as a
renewable feedstock because of their potential for mass production, having the
advantages of rapid growth, high-oil yield per unit area, and being cultivated on non-
arable land. Conversely, there is the growing problem of waste-tyre disposal globally.
Most people are aware that ELTs are a significant environmental hazard, but few know
the extent of the mass that is generated each year. It has been reported that each year
over one billion waste tyres are generated worldwide and this is expected to increase
to 1.5 billion by 2020, which is a huge problem in terms of waste disposal.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 150
8.1.2 Thermochemical conversion
Thermochemical conversion is the use of heat, with or without the presence of
oxygen, to convert various feedstocks into other forms of energy. Among different
thermochemical conversion processes, pyrolysis and hydrothermal conversion are
most popular for their smooth operation. Microalgae can be solvent extracted to
recover lipids, which subsequently undergo a traditional transesterification reaction to
produce FAMEs—normally known as biodiesel. However, for microalgae, the raw
material should be dried (at considerable expense) prior to the solvent extraction. A
second method undergoing intensive research is HTL, which can utilise wet biomass
to produce a biocrude. HTL converts biomass into gas, liquid and solids similar to
pyrolysis, but operates at a higher pressure and at a lower temperature. Tyres are an
organic waste from which useful energy in the form of liquid, gas or solid can be
derived. Meanwhile, the calorific values of rubber from tyres is 35–40 MJ/kg, so
vehicle tyres appear a very promising source of feedstock for fuel production.
However, Australian company GDT has invented a technique to produce an alternative
to diesel fuel from waste-disposal tyres. The technology reduces the full tyres to their
original constituents, which are carbon, steel, and tyre oil.
8.1.3 Analysis of physicochemical properties of fuel
The physicochemical properties of alternative fuel are important parameters to
consider in respect to the quality of the fuel and its application. The physicochemical
properties vary with the difference in chemical composition such as carbon-chain
length and the degree of saturation/unsaturation. Physicochemical properties include:
chemical composition, number of bonds in the molecule, molecular structure, fuel
density, viscosity, surface tension, heating value, CN, acid value, sulphur contents and
so on. These are the main factors that determine whether the fuel can be used in a
conventional engine. Moreover, the fuel properties affect the engine performance and
emission results. A number of studies have shown that fuel properties cause changes in
engine-exhaust emissions. There is widespread agreement that no single factor is
responsible for biodiesel engine performance and exhaust emissions. In this study, the
physicochemical properties have been analysed and it has been shown that changes in
those properties along with changes in the experimental condition for some microalgae
feedstock affect engine performance and exhaust emissions (see Chapter 4). The
physicochemical properties exhibited by microalge HTL biocrude show significant
Chapter 8: Conclusions and Recommendations 151
differences to microalgae FAME, conventional biofuel and diesel. The HTL results in
the breakdown of long-chain fatty acids, yielding shorter molecules and different
cyclic carbohydrates, giving higher yields. For microalgae, solvent extraction obtains
nonpolar storage lipids and membrane lipids along with some pigments. The variation
in the chemical composition, such as carbon-chain length and the degree of
saturation/unsaturation, changes the physicochemical properties of the biofuel.
Similarly, a careful analysis of waste-tyre oil was carried out and compared to diesel
fuel. The GDT-tyre oil is black and has a recognisable odour. The carbon residue
content is high compared to standard diesel fuel but if this is reduced it will help to
improve the fuel colour. The percentage of polycyclic aromatic HC and sulphur need
to be reduced so they fall within the range of regular diesel. At present, it is more
suitable for some off-road applications.
8.1.4 Diesel engine test
There is no literature available to validate the use of microalgae HTL biocrude
in diesel engine performance since its physiochemical properties make it unsuitable
for such use. Chapter 2 contains a detailed literature review of microalgae alternative
fuel. In this research, a new surrogate fuel was developed, which was suitable for a
diesel engine test. The experimental investigation of HTL microalgae surrogate fuel in
engine performance and emission characteristics is presented in Chapter 5. On the
other hand, information regarding the effect of waste-tyre oil on engine performance
and emission characteristics is extremely limited in the literature and even less
information is available in relation to turbo-charged diesel engines. Chapter 3
presented a detailed literature review on this topic.
In this study, it was found that HTL microalgae surrogate blended with diesel
(10%, 20% and 50%) in a turbo-charged common-rail diesel engine, generates almost
the same power as diesel alone. HTL microalgae surrogate blends have significant
variations when compared to petroleum diesel, especially in relation to gaseous
emissions. There is a significant increase in CO2, NO, and NOx emissions with all
blends when compared to petroleum diesel. However, the HC emissions reduce
significantly with microalgae-methyl-ester blends. After investigating all the
microalgae-methyl-ester blends, it was found that a 20% microalgae blend with
petroleum diesel showed the closest performance to petroleum diesel.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 152
The GDT-tyre oil was blended with diesel at two different volume percentages
(10% and 20%). The properties of GDT-tyre oil were measured and compared with
regular diesel before the experiments were conducted. There was no change found in
engine performance using tyre-oil blends when compared to diesel. Conversely, the
brake-specific exhaust emissions of NO2, NOx, CO, PM, and PN, were measured and
a significant change was found. The brake-specific NOx decreased by approximately
30% for each load, with increased percentages of GDT-tyre oil in the blends.
Conversely, it was observed that brake-specific emissions of CO increased slightly
with GDT-tyre-oil-blended fuels. PM and PN also showed a decrease in the
experimental results. The PM reduced by more than one-third for GDT-tyre oil
compared to diesel fuel for each load. GDT-tyre oil properties, especially CN, HHV
and density, were almost the same as diesel. There was also separation found in the
blends, which may be the reason for such results. The results from GDT-tyre oil are
very encouraging for future use as an alternative fuel to diesel in CI engines. However,
tests including aging, reliability, and durability need to be conducted before these fuels
can be used in engines.
8.2 APPLICATION OF OUTCOMES
The outcomes of this research could be implemented in industry to produce
alternative fuels. Microalgae biocrude could be used directly in marine-diesel engines.
Considering the increasing number of waste tyres every year all over the world, this
waste removal problem could be solved by converting the tyre into fuel using GDT
technology.
8.3 LIMITATIONS
There are some limitations in this research, which are summarised below.
Enough biocrude cannot be produced due to limitations of feedstocks.
The waste-tyre oil tested up to 20% by volume.
The production cost of microalgae biofuel is expensive compared to
mineral diesel fuel.
Chapter 8: Conclusions and Recommendations 153
8.4 RECOMMENDATIONS AND FUTURE STUDIES
There are several further studies that could be carried out to continue this
research. Regarding microalgae biofuel production, hybrid conversion techniques
could reduce production costs.
Two-stage biofuel production is a method that combines solvent-extracted lipids
into biofuel through a FAME-based process and biocrude by the HTL method. This is
a hybrid conversion method, as shown in Figure 8.1. The microalgae biomass is
converted into biofuel and the biomass waste, after solvent extraction, is used to
produce biocrude through the HTL process. The waste that comes from HTL is then
used as a fertiliser. At the same time, the heat produced from the HTL reactor is used
to produce steam, which can be used to produce electric power. The products are a
CO2-rich gas and water with nutrients that can be used to grow microalgae. This
proposed technique should reduce the per unit biofuel cost and simultaneously help to
recycle all waste produced through the conversion process.
Dry
microalgae
Solvent
extractor
Transesteri-
ficationBiodiesel
Biomass after
lipid extraction
Hydrothermal
liquefactionBio-crude
Solid residule
CO2 rich gas
Water and nutrients recycle
Fertilizer
Heat recovery
Hot water Cold water
Electricity
generationMicroalgae
Fuel pump
Figure 8.1: Microalgae hybrid conversion process.
A current challenge for researchers is the production cost of microalgae biofuel, which
is still expensive compared to mineral diesel fuel. It is possible to reduce the
microalgae biofuel production cost with hybrid production. However, the literature
Solvent extraction
HTL
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 154
shows that most of the cost comes from the cultivation of microalgae, which is about
20–30% of the total cost [87, 244]. It has been estimated that the microalgae biomass
production cost per kilogram is $2.95 and $3.80 for photobioreactors and raceways,
respectively. The microalgae production cost would be reduced to approximately
$0.47 and $0.60 per kilogram for photobioreactors and raceways respectively if the
production capacity increased to 10,000 tons per year. Considering microalgae
biomass is 30% oil by weight, then the cost of the biomass for providing a litre of oil
would be approximately $1.40 and $1.81 for photobioreactors and raceways,
respectively [87, 245]. This is still expensive compared to normal diesel fuel.
However, the microalgae biofuel production cost would be reduced further using the
proposed hybrid conversion technology. For microalgae biofuel to be competitive with
diesel, the algal oil price should be less than $1/L and this may be possible using a
hybrid technology.
Chapter 8: Conclusions and Recommendations 155
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 156
Bibliography
[1] Cremonez PA, Feroldi M, Feiden A, Gustavo Teleken J, José Gris D, Dieter J,
et al. Current scenario and prospects of use of liquid biofuels in South America.
Renewable and Sustainable Energy Reviews 2015;43:352-62.
[2] Azad AK, Rasul MG, Khan MMK, Sharma SC, Hazrat MA. Prospect of
biofuels as an alternative transport fuel in Australia. Renewable and
Sustainable Energy Reviews 2015;43:331-51.
[3] Islam MA, Rahman MM, Heimann K, Nabi MN, Ristovski ZD, Dowell A, et
al. Combustion analysis of microalgae methyl ester in a common rail direct
injection diesel engine. Fuel 2015;143:351-60.
[4] Islam MA, Brown RJ, O’Hara I, Kent M, Heimann K. Effect of temperature
and moisture on high pressure lipid/oil extraction from microalgae. Energy
Conversion and Management 2014;88(0):307-16.
[5] Nabi MN, Rahman MM, Islam MA, Hossain FM, Brooks P, Rowlands WN, et
al. Fuel characterisation, engine performance, combustion and exhaust
emissions with a new renewable Licella biofuel. Energy Conversion and
Management 2015;96:588-98.
[6] Jahirul M, Koh W, Brown R, Senadeera W, Hara I, Moghaddam L. Biodiesel
Production from Non-Edible Beauty Leaf (Calophyllum inophyllum) Oil:
Process Optimization Using Response Surface Methodology (RSM). Energies
2014;7(8):5317.
[7] Jahirul MI, Brown RJ, Senadeera W, Ashwath N, Rasul MG, Rahman MM, et
al. Physio-chemical assessment of beauty leaf (Calophyllum inophyllum) as
second-generation biodiesel feedstock. Energy Reports 2015;1:204-15.
[8] Rahman M, Rasul M, Hassan N. Study on the Tribological Characteristics of
Australian Native First Generation and Second Generation Biodiesel Fuel.
Energies 2017;10(1):55.
[9] Grima EM, González MJI, Giménez AG. Solvent Extraction for Microalgae
Lipids. In: Borowitzka MA, Moheimani NR, editors. Algae for Biofuels and
Energy. Dordrecht: Springer Netherlands; 2013, p. 187-205.
[10] Islam M, Magnusson M, Brown R, Ayoko G, Nabi M, Heimann K. Microalgal
Species Selection for Biodiesel Production Based on Fuel Properties Derived
from Fatty Acid Profiles. Energies 2013;6(11):5676-702.
[11] Chiaramonti D, Prussi M, Buffi M, Rizzo AM, Pari L. Review and
experimental study on pyrolysis and hydrothermal liquefaction of microalgae
for biofuel production. Applied Energy 2017;185, Part 2:963-72.
[12] Williams PT. Pyrolysis of waste tyres: A review. Waste Management
2013;33(8):1714-28.
[13] İlkılıç C, Aydın H. Fuel production from waste vehicle tires by catalytic
pyrolysis and its application in a diesel engine. Fuel Processing Technology
2011;92(5):1129-35.
[14] Martínez JD, Murillo R, García T, Veses A. Demonstration of the waste tire
pyrolysis process on pilot scale in a continuous auger reactor. Journal of
Hazardous Materials 2013;261:637-45.
[15] de Marco Rodriguez I, Laresgoiti MF, Cabrero MA, Torres A, Chomón MJ,
Caballero B. Pyrolysis of scrap tyres. Fuel Processing Technology
2001;72(1):9-22.
Bibliography 157
[16] Islam MR, Joardder MUH, Hasan SM, Takai K, Haniu H. Feasibility study for
thermal treatment of solid tire wastes in Bangladesh by using pyrolysis
technology. Waste Management 2011;31(9–10):2142-9.
[17] Laresgoiti MF, Caballero BM, de Marco I, Torres A, Cabrero MA, Chomón
MJ. Characterization of the liquid products obtained in tyre pyrolysis. Journal
of Analytical and Applied Pyrolysis 2004;71(2):917-34.
[18] GDT. Green distillation technologies corporation Ltd http://wwwgdtc6com/
25/08/2016.
[19] Davis R, Aden A, Pienkos PT. Techno-economic analysis of autotrophic
microalgae for fuel production. Applied Energy 2011;88(10):3524-31.
[20] Razon LF, Tan RR. Net energy analysis of the production of biodiesel and
biogas from the microalgae: Haematococcus pluvialis and Nannochloropsis.
Applied Energy 2011;88(10):3507-14.
[21] Darzins A, Pienkos P, L. E. Current status and potential for algal biofuels
production, a report to IEA Bioenergy Task 39. . IEA Bioenergy 2010. Report
T39-T2. .
[22] Doshi A, Pascoe S, Coglan L, Rainey T. The financial feasibility of microalgae
biodiesel in an integrated, multi-output production system. . Submitted 2017.
[23] Raheem A, Wan Azlina WAKG, Taufiq Yap YH, Danquah MK, Harun R.
Thermochemical conversion of microalgal biomass for biofuel production.
Renewable and Sustainable Energy Reviews 2015;49:990-9.
[24] Vihar R, Seljak T, Rodman Oprešnik S, Katrašnik T. Combustion
characteristics of tire pyrolysis oil in turbo charged compression ignition
engine. Fuel 2015;150:226-35.
[25] TSA. Tyre Stewardship Australia http://wwwtyrestewardshiporgau 2017.
[26] Martínez JD, Rodríguez-Fernández J, Sánchez-Valdepeñas J, Murillo R,
García T. Performance and emissions of an automotive diesel engine using a
tire pyrolysis liquid blend. Fuel 2014;115:490-9.
[27] BREE. Australian Bureau of Resource and Energy Economics wwwbreegovau
2013.
[28] FGE. Facts global energy wwwfgenergycom 2013.
[29] Yilmaz N, Vigil FM, Burl Donaldson A, Darabseh T. Investigation of CI
engine emissions in biodiesel–ethanol–diesel blends as a function of ethanol
concentration. Fuel 2014;115:790-3.
[30] Bodisco T, Reeves R, Situ R, Brown R. Bayesian models for the determination
of resonant frequencies in a DI diesel engine. Mechanical Systems and Signal
Processing 2012;26:305-14.
[31] Nabi MN, Brown RJ, Ristovski Z, Hustad JE. A comparative study of the
number and mass of fine particles emitted with diesel fuel and marine gas oil
(MGO). Atmospheric Environment 2012;57:22-8.
[32] Eboibi BE-O, Lewis DM, Ashman PJ, Chinnasamy S. Hydrothermal
liquefaction of microalgae for biocrude production: Improving the biocrude
properties with vacuum distillation. Bioresource Technology 2014;174:212-
21.
[33] Díaz-Vázquez LM, Rojas-Pérez A, Fuentes-Caraballo M, Robles-Ramos IV,
Jena U, Das KC. Demineralization of Sargassum spp. macroalgae biomass:
selective hydrothermal liquefaction process for bio-oil production. Frontiers in
Energy Research 2015;3.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 158
[34] Wahlen BD, Morgan MR, McCurdy AT, Willis RM, Morgan MD, Dye DJ, et
al. Biodiesel from Microalgae, Yeast, and Bacteria: Engine Performance and
Exhaust Emissions. Energy & Fuels 2013;27(1):220-8.
[35] Mata TM, Martins AA, Caetano NS. Microalgae for biodiesel production and
other applications: A review. Renewable and Sustainable Energy Reviews
2010;14(1):217-32.
[36] Elliott DC, Hart TR, Neuenschwander GG, Rotness LJ, Roesijadi G, Zacher
AH, et al. Hydrothermal processing of macroalgal feedstocks in continuous-
flow reactors. ACS Sustainable Chemistry & Engineering 2014;2:07-215.
[37] Kanda H, Li P, Ikehara T, Yasumoto-Hirose M. Lipids extracted from several
species of natural blue–green microalgae by dimethyl ether: Extraction yield
and properties. Fuel 2012;95:88-92.
[38] Chen Y-H, Huang B-Y, Chiang T-H, Tang T-C. Fuel properties of microalgae
(Chlorella protothecoides) oil biodiesel and its blends with petroleum diesel.
Fuel 2012;94:270-3.
[39] Wisniewski Jr A, Wiggers VR, Simionatto EL, Meier HF, Barros AAC,
Madureira LAS. Biofuels from waste fish oil pyrolysis: Chemical composition.
Fuel 2010;89(3):563-8.
[40] Hussain J, Ruan Z, Nascimento IA, Liu Y, Liao W. Lipid profiling and
corresponding biodiesel quality of Mortierella isabellina using different drying
and extraction methods. Bioresource Technology 2014;169:768-72.
[41] Dandı̇k L, Aksoy HA. Effect of catalyst on the pyrolysis of used oil carried out
in a fractionating pyrolysis reactor. Renewable Energy 1999;16(1–4):1007-10.
[42] Adebanjo AO, Dalai AK, Bakhshi NN. Production of Diesel-Like Fuel and
Other Value-Added Chemicals from Pyrolysis of Animal Fat. Energy & Fuels
2005;19(4):1735-41.
[43] Hedayat F, Stevanovic S, Milic A, Miljevic B, Nabi MN, Zare A, et al.
Influence of oxygen content of the certain types of biodiesels on particulate
oxidative potential Science of the Total Environment 2016;546:381-8.
[44] Surawski NC, Miljevic B, Roberts BA, Modini RL, Situ R, Brown RJ, et al.
Particle Emissions, Volatility, and Toxicity from an Ethanol Fumigated
Compression Ignition Engine. Environmental Science & Technology
2009;44(1):229-35.
[45] Barrios CC, Martín C, Domínguez-Sáez A, Álvarez P, Pujadas M, Casanova J.
Effects of the addition of oxygenated fuels as additives on combustion
characteristics and particle number and size distribution emissions of a TDI
diesel engine. Fuel 2014;132:93-100.
[46] Nabi MN, Minami M, Ogawa H, Miyamoto N. Ultra low emission and high
performance diesel combustion with highly oxygenated fuel. SAE Tech Pap
Ser; 2000, 2000-01-0231 2000.
[47] Eboibi BE, Lewis DM, Ashman PJ, Chinnasamy S. Effect of operating
conditions on yield and quality of biocrude during hydrothermal liquefaction
of halophytic microalga Tetraselmis sp. Bioresource Technology 2014;170:20-
9.
[48] Tommaso G, Chen W-T, Li P, Schideman L, Zhang Y. Chemical
characterization and anaerobic biodegradability of hydrothermal liquefaction
aqueous products from mixed-culture wastewater algae. Bioresource
Technology 2015;178:139-46.
Bibliography 159
[49] Jena U, Das KC, Kastner JR. Effect of operating conditions of thermochemical
liquefaction on biocrude production from Spirulina platensis. Bioresource
Technology 2011;102(10):6221-9.
[50] Zhou D, Zhang L, Zhang S, Fu H, Chen J. Hydrothermal Liquefaction of
Macroalgae Enteromorpha prolifera to Bio-oil. Energy & Fuels
2010;24(7):4054-61.
[51] Xu Y-P, Duan P-G, Wang F. Hydrothermal processing of macroalgae for
producing crude bio-oil. Fuel Processing Technology 2015;130:268-74.
[52] Xu C, Lad N. Production of Heavy Oils with High Caloric Values by Direct
Liquefaction of Woody Biomass in Sub/Near-critical Water. Energy & Fuels
2008;22(1):635-42.
[53] Elliott DC, Hart TR, Neuenschwander GG, Rotness LJ, Roesijadi G, Zacher
AH, et al. Hydrothermal processing of macroalgal feedstocks in continuous-
flow reactors,. ACS Sustain Chem Eng 2 2014;07–215.
[54] López Barreiro D, Prins W, Ronsse F, Brilman W. Hydrothermal liquefaction
(HTL) of microalgae for biofuel production: State of the art review and future
prospects. Biomass and Bioenergy 2013;53:113-27.
[55] Dote Y, Sawayama S, Inoue S, Minowa T, Yokoyama S-y. Recovery of liquid
fuel from hydrocarbon-rich microalgae by thermochemical liquefaction. Fuel
1994;73(12):1855-7.
[56] Sawayama S, Minowa T, Yokoyama SY. Possibility of renewable energy
production and CO2 mitigation by thermochemical liquefaction of microalgae.
Biomass and Bioenergy 1999;17(1):33-9.
[57] Rahman MM, Pourkhesalian AM, Jahirul MI, Stevanovic S, Pham PX, Wang
H, et al. Particle emissions from biodiesels with different physical properties
and chemical composition. Fuel 2014;134:201-8.
[58] Hasanuzzamana M, Hossain FM, Rahim NA. Palm Oil EFB: green energy
source in Malaysia. Applied Mechanics and Materials 2014;619:376-80.
[59] Patil V, Tran KQ, Giselrod HR. Toward sustainable production of biofuels
from microalgae. Int J Mol Sci 2008;9:1188–95.
[60] Amin S. Review on biofuel oil and gas production processes from microalgae.
Energy Conversion and Management 2009;50(7):1834-40.
[61] Sambusiti C, Bellucci M, Zabaniotou A, Beneduce L, Monlau F. Algae as
promising feedstocks for fermentative biohydrogen production according to a
biorefinery approach: A comprehensive review. Renewable and Sustainable
Energy Reviews 2015;44:20-36.
[62] Medina AR, Grima EM, Giménez AG, Gonzalez M. Downstream processing
of algal polyunsaturated fatty acids. Biotechnology Advances 1998;16(3):517-
80.
[63] Demirbaş A. Production of biodiesel from algae oils. Energy Sources part A
2009;31:163–8.
[64] Dutta R, Sarkar U, Mukherjee A. Extraction of oil from Crotalaria Juncea seeds
in a modified Soxhlet apparatus: Physical and chemical characterization of a
prospective bio-fuel. Fuel 2014;116(0):794-802.
[65] Jahirul MI, Brown RJ, Senadeera W, Ashwath N, Rasul M, Rahman MM, et
al. Physio-chemical assessment of beauty leaf (Calophyllum inophyllum) as
second-generation biodiesel feedstock. Energy Reports 2015;1:204-15.
[66] Pragya N, Pandey KK, Sahoo PK. A review on harvesting, oil extraction and
biofuels production technologies from microalgae. Renewable and Sustainable
Energy Reviews 2013;24(0):159-71.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 160
[67] Brennan L, Owende P. Biofuels from microalgae—A review of technologies
for production, processing, and extractions of biofuels and co-products.
Renewable and Sustainable Energy Reviews 2010;14(2):557-77.
[68] Srirangan K, Akawi L, Moo-Young M, Chou CP. Towards sustainable
production of clean energy carriers from biomass resources. Applied Energy
2012;100:172-86.
[69] Zhang L, Xu C, Champagne P. Overview of recent advances in thermo-
chemical conversion of biomass. Energy Conversion and Management
2010;51(5):969-82.
[70] Faeth JL, Valdez PJ, Savage PE. Fast Hydrothermal Liquefaction of
Nannochloropsis sp. To Produce Biocrude. Energy & Fuels 2013;27(3):1391-
8.
[71] Xiaowei P, Xiaoqian M, Yousheng L, Xusheng W, Xiaoshen Z, Cheng Y.
Effect of process parameters on solvolysis liquefaction of Chlorella
pyrenoidosa in ethanol–water system and energy evaluation. Energy
Conversion and Management 2016;117:43-63.
[72] Anastasakis K, Ross AB. Hydrothermal liquefaction of the brown macro-alga
Laminaria Saccharina: Effect of reaction conditions on product distribution and
composition. Bioresource Technology 2011;102(7):4876-83.
[73] Giakoumis EG. A statistical investigation of biodiesel physical and chemical
properties, and their correlation with the degree of unsaturation. Renewable
Energy 2013;50:858-78.
[74] Varatharajan K, Cheralathan M. Influence of fuel properties and composition
on NOx emissions from biodiesel powered diesel engines: A review.
Renewable and Sustainable Energy Reviews 2012;16(6):3702-10.
[75] Pandey RK, Rehman A, Sarviya RM. Impact of alternative fuel properties on
fuel spray behavior and atomization. Renewable and Sustainable Energy
Reviews 2012;16(3):1762-78.
[76] Kegl B. Effects of biodiesel on emissions of a bus diesel engine. Bioresource
Technology 2008;99(4):863-73.
[77] Vajda B, Lešnik L, Bombek G, Biluš I, Žunič Z, Škerget L, et al. The numerical
simulation of biofuels spray. Fuel 2015;144:71-9.
[78] Rakopoulos CD, Dimaratos AM, Giakoumis EG, Rakopoulos DC.
Investigating the emissions during acceleration of a turbocharged diesel engine
operating with bio-diesel or n-butanol diesel fuel blends. Energy
2010;35(12):5173-84.
[79] Kim D, Kim S, Oh S, No S-Y. Engine performance and emission
characteristics of hydrotreated vegetable oil in light duty diesel engines. Fuel
2014;125:36-43.
[80] Zare A, Nabi MN, Bodisco TA, Hossain FM, Rahman M, Ristovski ZD, et al.
The effect of triacetin as a fuel additive to waste cooking biodiesel on engine
performance and exhaust emissions. Fuel 2016;182:640-9.
[81] Nabi MN. Theoretical investigation of engine thermal efficiency, adiabatic
flame temperature, NOx emission and combustion-related parameters for
different oxygenated fuels. Applied Thermal Engineering 2010;30(8–9):839-
44.
[82] DieselNet. What Are Diesel Emissions.
https://wwwdieselnetcom/(21/05/2015) 2015.
Bibliography 161
[83] McCormick R, Graboski M, Alleman T, Herring A, Tyson S. Impact of
biodiesel source material and chemical structure on emissions of criteria
pollutants from a heavy-duty engine. Environ Sci Technol 2001;35:1742–7.
[84] Song H, Tompkins BT, Bittle JA, Jacobs TJ. Comparisons of NO emissions
and soot concentrations from biodiesel-fuelled diesel engine. Fuel
2012;96:446-53.
[85] Agarwal AK. Biofuels (alcohols and biodiesel) applications as fuels for
internal combustion engines. Progress in Energy and Combustion Science
2007;33(3):233-71.
[86] Tüccar G, Özgür T, Aydın K. Effect of diesel–microalgae biodiesel–butanol
blends on performance and emissions of diesel engine. Fuel 2014;132:47-52.
[87] Tüccar G, Aydın K. Evaluation of methyl ester of microalgae oil as fuel in a
diesel engine. Fuel 2013;112:203-7.
[88] Kosinkova J, Ramirez JA, Nguyen J, Ristovski Z, Brown R, Lin C, et al.
Hydrothermal liquefaction of bagasse using ethanol and black liquor as
solvents. Biofuels, Bioproducts and Biorefining 2015;9(6):630-8.
[89] Ross AB, Biller P, Kubacki ML, Li H, Lea-Langton A, Jones JM.
Hydrothermal processing of microalgae using alkali and organic acids. Fuel
2010;89(9):2234-43.
[90] Torri C, Garcia Alba L, Samorì C, Fabbri D, Brilman DWF. Hydrothermal
Treatment (HTT) of Microalgae: Detailed Molecular Characterization of HTT
Oil in View of HTT Mechanism Elucidation. Energy & Fuels 2012;26(1):658-
71.
[91] Minowa T, Yokoyama S-y, Kishimoto M, Okakura T. Oil production from
algal cells of Dunaliella tertiolecta by direct thermochemical liquefaction. Fuel
1995;74(12):1735-8.
[92] Hossain FH, Kosinkova J, Brown RJ, Ristovski R, Stephens E, Hankamer B,
et al. Chemical-physical properties of a HTL biocrude from a high growth-rate
microalga at a larger laboratory scale. Energy and Fuels (Submitted on
September, 2016) 2016.
[93] Li D, Chen L, Xu D, Zhang X, Ye N, Chen F, et al. Preparation and
characteristics of bio-oil from the marine brown alga Sargassum patens C.
Agardh. Bioresource Technology 2012;104:737-42.
[94] Duan P, Bai X, Xu Y, Zhang A, Wang F, Zhang L, et al. Catalytic upgrading
of crude algal oil using platinum/gamma alumina in supercritical water. Fuel
2013;109:225-33.
[95] Duan P, Chang Z, Xu Y, Bai X, Wang F, Zhang L. Hydrothermal processing
of duckweed: Effect of reaction conditions on product distribution and
composition. Bioresource Technology 2013;135:710-9.
[96] Reda AA, Schnelle-Kreis J, Orasche J, Abbaszade G, Lintelmann J, Arteaga-
Salas JM, et al. Gas phase carbonyl compounds in ship emissions: Differences
between diesel fuel and heavy fuel oil operation. Atmospheric Environment
2014;94:467-78.
[97] Zheng Z, Tang X, Asa-Awuku A, Jung HS. Characterization of a method for
aerosol generation from heavy fuel oil (HFO) as an alternative to emissions
from ship diesel engines. Journal of Aerosol Science 2010;41(12):1143-51.
[98] Wan Ghazali WNM, Mamat R, Masjuki HH, Najafi G. Effects of biodiesel
from different feedstocks on engine performance and emissions: A review.
Renewable and Sustainable Energy Reviews 2015;51:585-602.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 162
[99] Pham PX, Bodisco TA, Stevanovic S, Rahman MD, Wang H, Ristovski ZD, et
al. Engine Performance Characteristics for Biodiesels of Different Degrees of
Saturation and Carbon Chain Lengths. SAE Int J Fuels Lubr 2013;6(1):188-98.
[100] Choi CY, Reitz RD. An experimental study on the effects of oxygenated fuel
blends and multiple injection strategies on DI diesel engine emissions. Fuel
1999;78(11):1303-17.
[101] Utlu Z, Koçak MS. The effect of biodiesel fuel obtained from waste frying oil
on direct injection diesel engine performance and exhaust emissions.
Renewable Energy 2008;33(8):1936-41.
[102] Hansen A, Gratton M, Yuan W. Diesel engine performance and NOx emissions
from oxygenated biofuels and blends with diesel fuel. ASABE
2006;49(3):589-95.
[103] Öner C, Altun Ş. Biodiesel production from inedible animal tallow and an
experimental investigation of its use as alternative fuel in a direct injection
diesel engine. Applied Energy 2009;86(10):2114-20.
[104] Aydin H, Bayindir H. Performance and emission analysis of cottonseed oil
methyl ester in a diesel engine. Renewable Energy 2010;35(3):588-92.
[105] Ramadhas AS, Muraleedharan C, Jayaraj S. Performance and emission
evaluation of a diesel engine fueled with methyl esters of rubber seed oil.
Renewable Energy 2005;30(12):1789-800.
[106] Buyukkaya E. Effects of biodiesel on a DI diesel engine performance, emission
and combustion characteristics. Fuel 2010;89(10):3099-105.
[107] Kaplan C, Arslan R, Sürmen A. Performance Characteristics of Sunflower
Methyl Esters as Biodiesel. Energy Sources, Part A: Recovery, Utilization, and
Environmental Effects 2006;28(8):751-5.
[108] Lin L, Cunshan Z, Vittayapadung S, Xiangqian S, Mingdong D. Opportunities
and challenges for biodiesel fuel. Applied Energy 2011;88(4):1020-31.
[109] Demirbas A. Progress and recent trends in biofuels. Progress in Energy and
Combustion Science 2007;33(1):1-18.
[110] Surawski NC, Ristovski ZD, Brown RJ, Situ R. Gaseous and particle emissions
from an ethanol fumigated compression ignition engine. Energy Conversion
and Management 2012;54(1):145-51.
[111] Lapuerta M, Armas O, Rodríguez-Fernández J. Effect of biodiesel fuels on
diesel engine emissions. Progress in Energy and Combustion Science
2008;34(2):198-223.
[112] Sarvi A, Lyyränen J, Jokiniemi J, Zevenhoven R. Particulate emissions from
large-scale medium-speed diesel engines: 2. Chemical composition. Fuel
Processing Technology 2011;92(10):2116-22.
[113] Gautam A, Agarwal AK. Experimental Investigations of Comparative
Performance, Emission and Combustion Characteristics of a Cottonseed
Biodiesel-Fueled Four-Stroke Locomotive Diesel Engine. International
Journal of Engine Research 2012;0(0):1-19.
[114] Ghadikolaei MA. Effect of alcohol blend and fumigation on regulated and
unregulated emissions of IC engines—A review. Renewable and Sustainable
Energy Reviews 2016;57:1440-95.
[115] Mat Yasin MH, Yusaf T, Mamat R, Fitri Yusop A. Characterization of a diesel
engine operating with a small proportion of methanol as a fuel additive in
biodiesel blend. Applied Energy 2014;114:865-73.
Bibliography 163
[116] Islam MA. Microalgae: an alternative source of biodiesel for the compression
ignition (CI) engine. Queensland University of Technology 2014;PhD
thesis:38.
[117] Makarevičienė V, Lebedevas S, Rapalis P, Gumbyte M, Skorupskaite V,
Žaglinskis J. Performance and emission characteristics of diesel fuel
containing microalgae oil methyl esters. Fuel 2014;120:233-9.
[118] Fisher BC, Marchese AJ, Volckens J, Lee T, Collett JL. Measurement of
gaseous and particulate emissions from algae-based fatty acid methyl esters.
SAE International Journal of Fuels and Lubricants 2010;3(2):292-321.
[119] Merico E, Donateo A, Gambaro A, Cesari D, Gregoris E, Barbaro E, et al.
Influence of in-port ships emissions to gaseous atmospheric pollutants and to
particulate matter of different sizes in a Mediterranean harbour in Italy.
Atmospheric Environment 2016;139:1-10.
[120] Diab F, Lan H, Ali S. Novel comparison study between the hybrid renewable
energy systems on land and on ship. Renewable and Sustainable Energy
Reviews 2016;63:452-63.
[121] Kasper A, Aufdenblatten S, Forss A, Mohr M, Burtscher H. Particulate
emissions from a low-speed marine diesel engine. Aerosol Science and
Technology 2007;41:24–32.
[122] Goldsworthy L, Goldsworthy B. Modelling of ship engine exhaust emissions
in ports and extensive coastal waters based on terrestrial AIS data – An
Australian case study. Environmental Modelling & Software 2015;63:45-60.
[123] Wang S, Meng Q, Liu Z. Bunker consumption optimization methods in
shipping: A critical review and extensions. Transportation Research Part E:
Logistics and Transportation Review 2013;53:49-62.
[124] Johnson GR, Juwono AM, Friend AJ, Cheung H-C, Stelcer E, Cohen D, et al.
Relating urban airborne particle concentrations to shipping using carbon based
elemental emission ratios. Atmospheric Environment 2014;95:525-36.
[125] Burgard DA, Bria CRM. Bridge-based sensing of NOx and SO2 emissions
from ocean-going ships. Atmospheric Environment 2016;136:54-60.
[126] Khan MY, Agrawal H, Ranganathan S, Welch WA, Miller JW, Cocker DR.
Greenhouse Gas and Criteria Emission Benefits through Reduction of Vessel
Speed at Sea. Environmental Science & Technology 2012;46(22):12600-7.
[127] Williams EJ, Lerner BM, Murphy PC, Herndon SC, Zahniser MS. Emissions
of NOx, SO2, CO, and HCHO from commercial marine shipping during Texas
Air Quality Study (TexAQS) 2006. Journal of Geophysical Research:
Atmospheres 2009;114(D21306):1-14.
[128] Murphy SM, Agrawal H, Sorooshian A, Padró LT, Gates H, Hersey S, et al.
Comprehensive Simultaneous Shipboard and Airborne Characterization of
Exhaust from a Modern Container Ship at Sea. Environmental Science &
Technology 2009;43(13):4626-40.
[129] Agrawal H, Malloy QGJ, Welch WA, Wayne Miller J, Cocker Iii DR. In-use
gaseous and particulate matter emissions from a modern ocean going container
vessel. Atmospheric Environment 2008;42(21):5504-10.
[130] Chen G, Huey LG, Trainer M, Nicks D, Corbett J, Ryerson T, et al. An
investigation of the chemistry of ship emission plumes during ITCT 2002.
Journal of Geophysical Research: Atmospheres 2005;110(D10):1-15.
[131] Sinha P, Hobbs PV, Yokelson RJ, Christian TJ, Kirchstetter TW, Bruintjes R.
Emissions of trace gases and particles from two ships in the southern Atlantic
Ocean. Atmospheric Environment 2003;37(15):2139-48.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 164
[132] Aydın H, İlkılıç C. Optimization of fuel production from waste vehicle tires by
pyrolysis and resembling to diesel fuel by various desulfurization methods.
Fuel 2012;102:605-12.
[133] Martínez JD, Puy N, Murillo R, García T, Navarro MV, Mastral AM. Waste
tyre pyrolysis – A review. Renewable and Sustainable Energy Reviews
2013;23:179-213.
[134] ETRMA. European tyre and rubber industry statistics. European tyre and
rubber manufacturing association http://wwwetrmaorg 2014.
[135] Sienkiewicz M, Kucinska-Lipka J, Janik H, Balas A. Progress in used tyres
management in the European Union: A review. Waste Management
2012;32(10):1742-51.
[136] Quek A, Balasubramanian R. Liquefaction of waste tires by pyrolysis for oil
and chemicals—A review. Journal of Analytical and Applied Pyrolysis
2013;101:1-16.
[137] Alguacil FJ, López Gómez FA, Ramos G. The recycling of end-of-life tyres.
Technological review. Revista de Metalurgia 2011;47:273-84.
[138] Tudu K, Murugan S, Patel SK. Effect of diethyl ether in a DI diesel engine run
on a tyre derived fuel-diesel blend. Journal of the Energy Institute
2016;89(4):525-35.
[139] Sharma A, Murugan S. Potential for using a tyre pyrolysis oil-biodiesel blend
in a diesel engine at different compression ratios. Energy Conversion and
Management 2015;93:289-97.
[140] Torretta V, Rada EC, Ragazzi M, Trulli E, Istrate IA, Cioca LI. Treatment and
disposal of tyres: Two EU approaches. A review. Waste Management
2015;45:152-60.
[141] Pehlken A, Müller DH. Using information of the separation process of
recycling scrap tires for process modelling. Resources, Conservation and
Recycling 2009;54(2):140-8.
[142] Bridgewater AV. Thermal conversion of biomass and waste. Bio-Energy
Research Group Aston University, Birmingham (UK) 2001.
[143] Bridgewater A. V. Peacocke G.V.C. Fast pyrolysis processes for biomass.
Renew Sustain Energy 2000:1-73.
[144] Zhang L, Zhou B, Duan P, Wang F, Xu Y. Hydrothermal conversion of scrap
tire to liquid fuel. Chemical Engineering Journal 2016;285:157-63.
[145] Doğan O, Çelik MB, Özdalyan B. The effect of tire derived fuel/diesel fuel
blends utilization on diesel engine performance and emissions. Fuel
2012;95:340-6.
[146] Panwar NL, Kothari R, Tyagi VV. Thermo chemical conversion of biomass –
Eco friendly energy routes. Renewable and Sustainable Energy Reviews
2012;16(4):1801-16.
[147] White JE, Catall WJ, Legendre BL. Biomass pyrolysis kinetics: a comparative
critical review with relevant agricultural residue case studies Anal Appl Pyrol
2011.
[148] Balat M, Balat M, Kırtay E, Balat H. Main routes for the thermo-conversion of
biomass into fuels and chemicals. Part 1: Pyrolysis systems. Energy
Conversion and Management 2009;50(12):3147-57.
[149] Ceylan R, Bredenberg JBs. Hydrogenolysis and hydrocracking of the carbon-
oxygen bond. 2. Thermal cleavage of the carbon-oxygen bond in guaiacol. Fuel
1982;61(4):377-82.
Bibliography 165
[150] Sergio Canzana Capareda. Biomass Energy Conversion. Texas A&M
University,USA (wwwintechopencom) 2013.
[151] Miranda M, Pinto F, Gulyurtlu I, Cabrita I. Pyrolysis of rubber tyre wastes: a
kinetic study. Fuel 2013;103:542-52.
[152] Banar M, Akyıldız V, Özkan A, Çokaygil Z, Onay Ö. Characterization of
pyrolytic oil obtained from pyrolysis of TDF (Tire Derived Fuel). Energy
Conversion and Management 2012;62:22-30.
[153] Islam MR, Joardder MUH, Kader M, Sarker M. Valorization of solid tire
wastes available in Bangladesh by thermal treatment. 2011.
[154] Aylón E, Fernández-Colino A, Murillo R, Navarro M, García T, Mastral A.
Valorisation of waste tyre by pyrolysis in a moving bed reactor. Waste
management 2010;30(7):1220-4.
[155] Zhang Y, Williams PT. Carbon nanotubes and hydrogen production from the
pyrolysis catalysis or catalytic-steam reforming of waste tyres. Journal of
Analytical and Applied Pyrolysis 2016;122:490-501.
[156] Song Z, Yang Y, Zhao X, Sun J, Wang W, Mao Y, et al. Microwave pyrolysis
of tire powders: Evolution of yields and composition of products. Journal of
Analytical and Applied Pyrolysis 2017;123:152-9.
[157] Luo S, Feng Y. The production of fuel oil and combustible gas by catalytic
pyrolysis of waste tire using waste heat of blast-furnace slag. Energy
Conversion and Management 2017;136:27-35.
[158] TC. Thermal cracking. wwwhnqingzhicom/solution/140html 2017.
[159] Murugan S, Ramaswamy MC, Nagarajan G. The use of tyre pyrolysis oil in
diesel engines. Waste Management 2008;28(12):2743-9.
[160] Hariharan S, Murugan S, Nagarajan G. Effect of diethyl ether on Tyre pyrolysis
oil fueled diesel engine. Fuel 2013;104:109-15.
[161] Conesa JA, Martín-Gullón I, Font R, Jauhiainen J. Complete Study of the
Pyrolysis and Gasification of Scrap Tires in a Pilot Plant Reactor.
Environmental Science & Technology 2004;38(11):3189-94.
[162] Li SQ, Yao Q, Chi Y, Yan JH, Cen KF. Pilot-scale pyrolysis of scrap tires in a
continuous rotary kiln reactor. Industrial and Engineering Chemistry Research
2004;43(17):5133-45.
[163] Galvagno S, Casu S, Casabianca T, Calabrese A, Cornacchia G. Pyrolysis
process for the treatment of scrap tyres: Preliminary experimental results.
Waste Management 2002;22(8):917-23.
[164] Olazar M, Aguado R, Arabiourrutia M, Lopez G, Barona A, Bilbao J. Catalyst
effect on the composition of tire pyrolysis products. Energy and Fuels
2008;22(5):2909-16.
[165] Aylón E, Murillo R, Fernández-Colino A, Aranda A, García T, Callén MS, et
al. Emissions from the combustion of gas-phase products at tyre pyrolysis.
Journal of Analytical and Applied Pyrolysis 2007;79(1–2):210-4.
[166] Tudu K, Murugan S, Patel SK. Effect of tyre derived oil-diesel blend on the
combustion and emissions characteristics in a compression ignition engine
with internal jet piston geometry. Fuel 2016;184:89-99.
[167] Oncel SS. Microalgae for a macroenergy world. Renewable and Sustainable
Energy Reviews 2013;26(0):241-64.
[168] d’Ippolito G, Sardo A, Paris D, Vella FM, Adelfi MG, Botte P, et al. Potential
of lipid metabolism in marine diatoms for biofuel production. Biotechnology
for Biofuels 2015;8(1):1-10.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 166
[169] Kosinkova J, Doshi A, Maire J, Ristovski Z, Brown R, Rainey TJ. Measuring
the regional availability of biomass for biofuels and the potential for
microalgae. Renewable and Sustainable Energy Reviews 2015;49:1271-85.
[170] Subramanian S, Barry AN, Pieris S, Sayre RT. Comparative energetics and
kinetics of autotrophic lipid and starch metabolism in chlorophytic microalgae:
implications for biomass and biofuel production. Biotechnology for Biofuels
2013;6(1):1-12.
[171] Guccione A, Biondi N, Sampietro G, Rodolfi L, Bassi N, Tredici MR.
Chlorella for protein and biofuels: from strain selection to outdoor cultivation
in a Green Wall Panel photobioreactor. Biotechnology for Biofuels
2014;7(1):1-12.
[172] Naveena B, Armshaw P, Tony Pembroke J. Ultrasonic intensification as a tool
for enhanced microbial biofuel yields. Biotechnology for Biofuels 2015;8(1):1-
13.
[173] Bennion EP, Ginosar DM, Moses J, Agblevor F, Quinn JC. Lifecycle
assessment of microalgae to biofuel: Comparison of thermochemical
processing pathways. Applied Energy 2015(0).
[174] Amin S. Review on biofuel oil and gas production processes from microalgae.
Energy Conversion and Management 2009;50(7):1834-40.
[175] Vardon DR, Sharma BK, Blazina GV, Rajagopalan K, Strathmann TJ.
Thermochemical conversion of raw and defatted algal biomass via
hydrothermal liquefaction and slow pyrolysis. Bioresource Technology
2012;109:178-87.
[176] Mandal S, Mallick N. Microalga Scenedesmus obliquus as a potential source
for biodiesel production. Applied Microbiology and Biotechnology
2009;84(2):281-91.
[177] Demirbas A. Progress and recent trends in biodiesel fuels. Energy Conversion
and Management 2009;50(1):14-34.
[178] Barreiro DL, Prins W, Ronsse F, Brilman W. Hydrothermal liquefaction (HTL)
of microalgae for biofuel production: state of the art review and future
prospects. Biomass and Bioenergy 2013;53:113-27.
[179] Xu D, Savage PE. Characterization of biocrudes recovered with and without
solvent after hydrothermal liquefaction of algae. Algal Research 2014;6, Part
A:1-7.
[180] Ramirez JA, Brown RJ, Rainey TJ. A Review of Hydrothermal Liquefaction
Bio-Crude Properties and Prospects for Upgrading to Transportation Fuels.
Energies 2015;8(7):6765-94.
[181] Biller P, Riley R, Ross A. Catalytic hydrothermal processing of microalgae:
decomposition and upgrading of lipids. Bioresource technology
2011;102(7):4841-8.
[182] Biller P, Ross A. Potential yields and properties of oil from the hydrothermal
liquefaction of microalgae with different biochemical content. Bioresource
Technology 2011;102(1):215-25.
[183] Brown TM, Duan P, Savage PE. Hydrothermal Liquefaction and Gasification
of Nannochloropsis sp. Energy & Fuels 2010;24(6):3639-46.
[184] Matsui T-o, Nishihara A, Ueda C, Ohtsuki M, Ikenaga N-o, Suzuki T.
Liquefaction of micro-algae with iron catalyst. Fuel 1997;76(11):1043-8.
[185] Valdez PJ, Dickinson JG, Savage PE. Characterization of product fractions
from hydrothermal liquefaction of Nannochloropsis sp. and the influence of
solvents. Energy & Fuels 2011;25(7):3235-43.
Bibliography 167
[186] Jakob G, Wolf J, Bui TV, Posten C, Kruse O, Stephens E, et al. Surveying a
Diverse Pool of Microalgae as a Bioresource for Future Biotechnological
Applications. J Phylogenetics Evol Biol 2013;4(153).
[187] Demirbas A. Calculation of Higher Heating Values of Biomass Fuels. Fuel
1997;76(431-434).
[188] Friedl A, Padouvas E, Rotter H, Varmuza K. Prediction of heating values of
biomass fuel from elemental composition. Analytica Chimica Acta
2005;544(1):191-8.
[189] Yu G, Zhang Y, Schideman L, Funk TL, Wang Z. Hydrothermal liquefaction
of low lipid content microalgae into bio-crude oil. American Society of
Agricultural Engineers 2011;54(1):239-46.
[190] Boie W. Fuel Technology Calculations. Energietechnik 3 1953:309-16.
[191] Xu C, Etcheverry T. Hydro-liquefaction of woody biomass in sub-and super-
critical ethanol with iron-based catalysts. Fuel 2008;87(3):335-45.
[192] Garcia Alba L, Torri C, Samorì C, van der Spek J, Fabbri D, Kersten SR, et al.
Hydrothermal treatment (HTT) of microalgae: evaluation of the process as
conversion method in an algae biorefinery concept. Energy & fuels
2011;26(1):642-57.
[193] Huang H, Yuan X, Zeng G, Wang J, Li H, Zhou C, et al. Thermochemical
liquefaction characteristics of microalgae in sub-and supercritical ethanol. Fuel
Processing Technology 2011;92(1):147-53.
[194] Toor SS, Rosendahl L, Rudolf A. Hydrothermal liquefaction of biomass: A
review of subcritical water technologies. Energy 2011;36(5):2328-42.
[195] Peterson AA, Vogel F, Lachance RP, Fröling M, Antal Jr MJ, Tester JW.
Thermochemical biofuel production in hydrothermal media: a review of sub-
and supercritical water technologies. Energy & Environmental Science
2008;1(1):32-65.
[196] Tyson KS, McCormick RL. Biodiesel handling and use guidelines.
Collingdale, United States: DIANE Publishing; 2006.
[197] Boelhouwer J, Nederbragt G, Verberg G. Viscosity data of organic liquids.
Applied Scientific Research 1951;2(1):249-68.
[198] Lang X, Dalai AK, Bakhshi NN, Reaney MJ, Hertz P. Preparation and
characterization of bio-diesels from various bio-oils. Bioresource technology
2001;80(1):53-62.
[199] Abramzon B, Sazhin S. Convective vaporization of a fuel droplet with thermal
radiation absorption. Fuel 2006;85(1):32-46.
[200] Vardon DR. Hydrothermal liquefaction for energy recovery from high-
moisture waste biomass. Master thesis, University of Illinois at Urbana
Champaign 2012:73.
[201] Elliott DC, Hart TR, Schmidt AJ, Neuenschwander GG, Rotness LJ, Olarte
MV, et al. Process development for hydrothermal liquefaction of algae
feedstocks in a continuous-flow reactor. Algal Research 2013;2(4):445-54.
[202] Situ R, Brown RJ, Ristovski Z, Kruger U, Hargreaves D. Analysis of Dual Fuel
Compression Ignition (Diesel) Engine. The Seventh International Conference
on Modeling and Diagnostics for Advanced Engine Systems 2008.
[203] Mofijur M, Masjuki H, Kalam M, Atabani A, Arbab M, Cheng S, et al.
Properties and use of Moringa oleifera biodiesel and diesel fuel blends in a
multi-cylinder diesel engine. Energy Conversion and Management
2014;82:169-76.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 168
[204] Pawar M, Kadam A, Yemul O, Thamke V, Kodam K. Biodegradable bioepoxy
resins based on epoxidized natural oil (cottonseed & algae) cured with
citric and tartaric acids through solution polymerization: A renewable
approach. Industrial Crops and Products 2016;89:434-47.
[205] Hossain FM, Rainey TJ, Ristovski Z, Brown RJ. Performance and exhaust
emissions of diesel engines using microalgae FAME and the prospects for
microalgae HTL biocrude. Renewable and Sustainable Energy Reviews
Available online 16 June 2017.
[206] Sari YW, Bruins ME, Sanders JPM. Enzyme assisted protein extraction from
rapeseed, soybean, and microalgae meals. Industrial Crops and Products
2013;43:78-83.
[207] Chen Y, Mu R, Yang M, Fang L, Wu Y, Wu K, et al. Catalytic hydrothermal
liquefaction for bio-oil production over CNTs supported metal catalysts.
Chemical Engineering Science 2017;161:299-307.
[208] Pitz WJ, Mueller CJ. Recent progress in the development of diesel surrogate
fuels. Progress in Energy and Combustion Science 2011;37(3):330-50.
[209] Mueller CJ, Cannella WJ, Bruno TJ, Bunting B, Dettman HD, Franz JA, et al.
Methodology for Formulating Diesel Surrogate Fuels with Accurate
Compositional, Ignition-Quality, and Volatility Characteristics. Energy &
Fuels 2012;26(6):3284-303.
[210] Liu X, Wang H, Wang X, Zheng Z, Yao M. Experimental and modelling
investigations of the diesel surrogate fuels in direct injection compression
ignition combustion. Applied Energy 2017;189:187-200.
[211] Wu S, Yang H, Hu J, Shen D, Zhang H, Xiao R. The miscibility of
hydrogenated bio-oil with diesel and its applicability test in diesel engine: A
surrogate (ethylene glycol) study. Fuel Processing Technology 2017;161:162-
8.
[212] Das DD, McEnally CS, Kwan TA, Zimmerman JB, Cannella WJ, Mueller CJ,
et al. Sooting tendencies of diesel fuels, jet fuels, and their surrogates in
diffusion flames. Fuel 2017;197:445-58.
[213] Dooley S, Won SH, Chaos M, Heyne J, Ju Y, Dryer FL, et al. A jet fuel
surrogate formulated by real fuel properties. Combustion and Flame
2010;157(12):2333-9.
[214] Abboud J, Schobing J, Legros G, Bonnety J, Tschamber V, Brillard A, et al.
Impacts of oxygenated compounds concentration on sooting propensities and
soot oxidative reactivity: Application to Diesel and Biodiesel surrogates. Fuel
2017;193:241-53.
[215] Hossain FM, Kosinkova J, Brown RJ, Ristovski Z, Hankamer B, Stephens E,
et al. Experimental Investigations of Physical and Chemical Properties for
Microalgae HTL Bio-Crude Using a Large Batch Reactor. Energies
2017;10(4):467.
[216] Collins CD. Implementing Phytoremediation of Petroleum Hydrocarbons. In:
Willey N, editor Phytoremediation: Methods and Reviews. Totowa, NJ:
Humana Press; 2007, p. 99-108.
[217] Babaie M, Davari P, Zare F, Rahman MM, Rahimzadeh H, Ristovski Z, et al.
Effect of Pulsed Power on Particle Matter in Diesel Engine Exhaust Using a
DBD Plasma Reactor. IEEE Transactions on Plasma Science 2013;41(8):2349-
58.
Bibliography 169
[218] Zare A, Bodisco TA, Nabi MN, Hossain FM, Rahman MM, Ristovski ZD, et
al. The influence of oxygenated fuels on transient and steady-state engine
emissions. Energy 2017;121:841-53.
[219] Prasad R, Bella VR. A Review on Diesel Soot Emission, its Effect and Control
Bulletin of Chemical Reaction Engineering & Catalysis 2010;5(2):69-86.
[220] Nabi MN, Zare A, Hossain FM, Rahman MM, Bodisco TA, Ristovski ZD, et
al. Influence of fuel-borne oxygen on European Stationary Cycle: Diesel
engine performance and emissions with a special emphasis on particulate and
NO emissions. Energy Conversion and Management 2016;127:187-98.
[221] Bodisco T, Brown RJ. Inter-cycle variability of in-cylinder pressure parameters
in an ethanol fumigated common rail diesel engine. Energy 2013;52:55-65.
[222] NREL. Compendium of experimental cetane numbers. National Renewable
Energy Laboratory 2004.
[223] Nabi N, Zare A, Hossain M, Rahman MM, Stuart D, Ristovski Z, et al.
Formulation of new oxygenated fuels and their influence on engine
performance and exhaust emissions. Proceedings of the 2015 Australian
Combustion Symposium. The Combustion Institute Australia and New Zealand
Section; 2015:64-7.
[224] P. SK, Gopal P, Aravind S. Performance analysis of diesel engine with diesel,
ethanol & vegetable oil blends International Journal of Chemical Sciences
2015;13(2):576-84.
[225] Rashed MM, Kalam MA, Masjuki HH, Habibullah M, Imdadul HK, Shahin
MM, et al. Improving oxidation stability and NOX reduction of biodiesel
blends using aromatic and synthetic antioxidant in a light duty diesel engine.
Industrial Crops and Products 2016;89:273-84.
[226] Tan YH, Abdullah MO, Nolasco-Hipolito C, Zauzi NSA, Abdullah GW.
Engine performance and emissions characteristics of a diesel engine fueled
with diesel-biodiesel-bioethanol emulsions. Energy Conversion and
Management 2017;132:54-64.
[227] Hernández JJ, Lapuerta M, Barba J. Separate effect of H2, CH4 and CO on
diesel engine performance and emissions under partial diesel fuel replacement.
Fuel 2016;165:173-84.
[228] Giakoumis EG, Rakopoulos CD, Dimaratos AM, Rakopoulos DC. Exhaust
emissions with ethanol or n-butanol diesel fuel blends during transient
operation: A review. Renewable and Sustainable Energy Reviews
2013;17:170-90.
[229] Hossain F, Nabi M, Rahman M, Zare A, Rainey T, Stuart D, et al. Experimental
investigation of the effects of oxygenated fuels on exhaust emissions in a heavy
duty diesel engine. Australian Combustion Symposium ,7-9 December,
University of Melbourne, Vic 2015:56-9.
[230] Xue J, Grift TE, Hansen AC. Effect of biodiesel on engine performances and
emissions. Renewable and Sustainable Energy Reviews 2011;15(2):1098-116.
[231] E J, Pham M, Zhao D, Deng Y, Le D, Zuo W, et al. Effect of different
technologies on combustion and emissions of the diesel engine fueled with
biodiesel: A review. Renewable and Sustainable Energy Reviews
2017;80:620-47.
[232] Kalargaris I, Tian G, Gu S. Combustion, performance and emission analysis of
a DI diesel engine using plastic pyrolysis oil. Fuel Processing Technology
2017;157:108-15.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 170
[233] Imtenan S, Masjuki HH, Varman M, Kalam MA, Arbab MI, Sajjad H, et al.
Impact of oxygenated additives to palm and jatropha biodiesel blends in the
context of performance and emissions characteristics of a light-duty diesel
engine. Energy Conversion and Management 2014;83:149-58.
[234] Ali OM, Mamat R, Abdullah NR, Abdullah AA. Analysis of blended fuel
properties and engine performance with palm biodiesel–diesel blended fuel.
Renewable Energy 2016;86:59-67.
[235] Aalam CS, Saravanan CG. Effects of nano metal oxide blended Mahua
biodiesel on CRDI diesel engine. Ain Shams Engineering Journal.
[236] Zabed H, Sahu JN, Boyce AN, Faruq G. Fuel ethanol production from
lignocellulosic biomass: An overview on feedstocks and technological
approaches. Renewable and Sustainable Energy Reviews 2016;66:751-74.
[237] Frigo S, Seggiani M, Puccini M, Vitolo S. Liquid fuel production from waste
tyre pyrolysis and its utilisation in a Diesel engine. Fuel 2014;116:399-408.
[238] Zare A, Bodisco T, Nabi N, Hossain M, Rahman MM, Stuart D, et al. Impact
of Triacetin as an oxygenated fuel additive to waste cooking biodiesel:
transient engine performance and exhaust emissions. Proceedings of the 2015
Australian Combustion Symposium. The Combustion Institute Australia and
New Zealand Section; 2015:48-51.
[239] Heywood JB. International Combustion Engine Fundamentals. McGraw-Hill,
Inc.
[240] Brunt MFJ, Platts KC. Calculation of Heat Release in Direct Injection Diesel
Engines. SAE International; 1999.
[241] Murugan S, Ramaswamy MC, Nagarajan G. Performance, emission and
combustion studies of a DI diesel engine using Distilled Tyre pyrolysis oil-
diesel blends. Fuel Processing Technology 2008;89(2):152-9.
[242] Nabi MN, Zare A, Hossain FM, Ristovski ZD, Brown RJ. Reductions in diesel
emissions including PM and PN emissions with diesel-biodiesel blends.
Journal of Cleaner Production 2017;166(Supplement C):860-8.
[243] Nabi MN, Zare A, Hossain FM, Ristovski ZD, Brown RJ. Reductions in diesel
emissions including PM and PN emissions with diesel-biodiesel blends.
Journal of Cleaner Production 2017.
[244] Demirbas A, Fatih Demirbas M. Importance of algae oil as a source of
biodiesel. Energy Conversion and Management 2011;52(1):163-70.
[245] Chisti Y. Biodiesel from microalgae. Biotechnology Advances
2007;25(3):294-306.
[246] Cambustion. DMS500 Fast Particle Analyzer.
http://wwwcambustioncom/products/dms500(2015/01/29).
[247] TSI. DustTrak II Aerosol Monitor 8530. http://wwwtsicom/dusttrak-ii-aerosol-
monitor-8530/(2015/01/29).
[248] Sayble. CA-10 Carbon Dioxide Analyzer. http://sablesyscom/products/classic-
line/ca-10-carbon-dioxide-analyzer/(2015/01/29).
Appendices
171
Appendices
Appendix Contents
A MICROALGAE HTL BIOCRUDE PRODUCTION
B FUEL CERTIFICATE
C DIESEL ENGINE PERFORMANCE WITH SURROGATE BLENDS
D DIESEL ENGINE PERFORMANCE WITH TYRE OIL
E BIOFUEL ENGINE RESEARCH FACILITY (BERF) AT QUT
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 172
APPENDIX A: MICROALGAE HTL BIOCRUDE PRODUCTION
Hydrothermal liquefaction (HTL) was carried out using a high pressure and
temperature Parr reactor, which is shown in Figure A-1. HTL converts biomass into
liquid fuels and it is generally carried out at 250–450 °C in 1.8 L volume. The retention
time in the reactor is usually 5–120 min. HTL results in the breakdown of long-chain
fatty acids to shorter molecules, and carbohydrates are converted to straight carbon
chains, giving high yields. The gaseous products were vented. The liquid bio-crude
products were separated from the liquefied raw product using solvent extraction to
simplify the chemical analyses.
Figure A-1: Thermal liquefaction Parr reactor (High Pressure and Temperature).
Appendices
173
APPENDIX B: FUEL CERTIFICATE
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 174
Appendices
175
APPENDIX C: DIESEL ENGINE PERFORMANCE WITH SURROGATE
BLENDS
Appendix C is supplementary to Chapter 6. Further detail of the P-CA, PV and
emissions curve can be found in Chapter 6.
Figure C-1: Variation of cylinder pressure with crank angle for 75% load for
different fuels.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 176
Figure C-2: Variation of cylinder pressure with crank angle for 25% load for
different fuels.
Figure C-3: Variation of cylinder pressure with crank angle for 75% load for
different fuels.
Appendices
177
Figure C-4: Variation of cylinder pressure with crank angle for 25% load for
different fuels.
Figure C-5: Variation of BMEP with engine load for different fuels.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 178
Figure C-6: Variation of NO with engine load for different fuels.
Appendices
179
APPENDIX D: DIESEL ENGINE PERFORMANCE TYRE-OIL BLENDS
Appendix D is supplementary to Chapter 7. Further detail of the P-CA, PV and
emissions curve can be found in Chapter 7.
Figure D-1: Variation of cylinder pressure with crank angle for 75% load for
different fuels.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 180
Figure D-2: Variation of cylinder pressure with crank angle for 25% load for
different fuels.
Figure D-4: Variation of cylinder pressure with crank angle for 75% load for
different fuels.
Appendices
181
Figure D-4: Variation of cylinder pressure with crank angle for 25% load for
different fuels.
Figure D-5: Variation of NO with engine load for different fuels.
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 182
APPENDIX E: BIOFUEL ENGINE RESEARCH FACILITY (BERF) AT QUT
Engine performance measurements:
Typically, diesel engine performance parameters refer to engine power, torque,
brake-specific fuel consumption (BSFC), brake thermal efficiency (BTE), indicated
pressure and brake mean effective pressure (BMEP). The engine’s operating data was
collected from the engine control unit (ECU) and in-cylinder pressure of cylinder one
data was collected using a pressure transducer.
Figure E-1: Six-cylinder turbo-charge EURO-III diesel engine.
Exhaust Emission measurements:
Different instruments—the DMS500, DustTrak and Sayble—were used to
measure particle number and mass, as well as other emissions. The gaseous emissions
such as CO, CO2, NO, NO2 and HC were also measured using laboratory-grade
equipment.
Appendices
183
DMS500. The Cambustion DMS500 is uniquely suited for a variety of diesel
particulate filter applications. The DMS500 remains the fastest available nanoparticle
size spectrometer with an output data rate of up to 10 Hz [246].
Figure E-2: Cambustion DMS500.
Dust Track. The DustTrak™ II Aerosol Monitor 8530 is a desktop battery-
operated, data-logging, light-scattering laser photometer that gives real-time aerosol
mass readings. It uses a sheath air system that isolates the aerosol in the optics
chamber to keep the optics clean for improved reliability and low maintenance. It
measures aerosol concentrations corresponding to PM1, PM2.5 or size fractions [247].
Farhad M Hossain (2017) PhD Thesis. -Experimental investigation of thermochemically-derived fuels in a diesel engine 184
Figure E-3: DustTrak™ II Aerosol Monitor 8530.
Sayble. The CA-10 Carbon Dioxide Analyser measures CO2 in a range of
applications from respirometry to industrial gas monitoring. It features a dual-
wavelength infrared sensor that provides stable, fast response in a broad CO2
measurement range. Operation is intuitive and flexible, allowing easy use by a wide
range of users. High resolution of 1 ppm at atmospheric levels ensures trustworthy
results [248].
Figure E-4: CA-10 Carbon Dioxide Analyser.
Top Related