Experimental Investigation of Single Cylinder 4s Si Engine With Hydrogen Blends

7/30/2019 Experimental Investigation of Single Cylinder 4s Si Engine With Hydrogen Blends

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International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 6340(Print), ISSN 0976 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) IAEME

84

EXPERIMENTAL INVESTIGATION OF SINGLE CYLINDER 4S SI

ENGINE WITH HYDROGEN BLENDS

Suhas B.G1, Shivaprasad K.V

2, Kumar G.N

3

1

M Tech Candidate, Mechanical Engineering Department, National Institute of TechnologyKarnataka, Surathkal, Mangalore.2 PhD Candidate, Mechanical Engineering Department, National Institute of Technology

Karnataka, Surathkal, Mangalore.3

Assistant Professor, Mechanical Engineering Department, National Institute of Technology

Karnataka, Surathkal, Mangalore.

ABSTRACT

Considering energy crises and pollution problems today much work has been done for alternativefuels for fossil fuels and lowering the toxic components in the combustion products. The present

investigation is to find performance and emission characteristics of a single cylinder sparkignition engine operating with hydrogen blends. The hydrogen is blended in different volumefraction of 3%, 6%, 9% and 12% of petrol in a four stroke single cylinder Villierss engine for

different load. The load is varied from no load to full load in steps of one fourth, half and three

forth of the full load. The engine in which the experiment to be conducted is a constant speedengine. The performance and emissions of engine such as, brake thermal efficiency, brake

specific energy consumption, volumetric Efficiency, exhaust gas temperature, carbon monoxide,

unburnt hydrocarbons and oxides of nitrogen are to be determined and compared with base linereadings of petrol.

Keywords: Back Fire, Brake specific energy consumption, Brake thermal efficiency, Emissions,

Exhaust gas temperature, Hydrogen and Volumetric efficiency.

1. INTRODUCTION

Fossil fuels such as petroleum, natural gas and coal meet most of the worlds energy demand, at

present time. But combustion products of these fossil fuels, such as carbon monoxide (CO),

carbon dioxide (CO2), oxides of sulfur (SOx), and oxides of nitrogen (NOx), hydrocarbon (HC),toxic metals, and ashes have been causing many environmental problems and posing great

INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING ANDTECHNOLOGY (IJMET)

ISSN 0976 6340 (Print)

ISSN 0976 6359 (Online)

Volume 3, Issue 3, Septmebr - December (2012), pp. 84-95

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danger for the world. Hydrogen has proved its suitability over many fuels in these criteria.

Hydrogen does not cause combustion problems such as vapor lock, cold wall quenching,

inadequate vaporization or poor mixing, and do not produce toxic products [1]. The limited fossilfuel resources and toxic emissions exhausted from internal combustion (IC) engines have pushed

the researches to focus on alternative fuels. Meanwhile, the high adiabatic flame speed of

hydrogen indicates that the combustion of hydrogen engines is much closer to ideal constantvolume combustion, which is beneficial for higher thermal efficiency. Since the energy density

of hydrogen on volume basis is much lower than that of gasoline, the hydrogen powered engines

sometimes also suffer a weak torque output [2]. Hydrogen has special properties so thecombustion characteristics of hydrogen are very different from gasoline. The laminar flame

speed of a hydrogen air mixture at stoichiometric condition is about ten times that of gasoline.

The wide flammability limit of hydrogen allows the use of very low equivalence ratios which

result in reducing NOx emissions. The octane rating of hydrogen of 106 RON allows increasingcompression ratio. Hydrogen is renewable and offers lots of other benefits. The most practical

one is its ability to run in bi-fuel conditions [3]. The limited fossil fuel reserves and increased air

pollution have pushed studies on improving the thermal efficiency and emissions performance of

internal combustion (IC) engines. Because of the decreased combustion temperature and reducedcharge homogeneity, spark-ignited (SI) engines always expel large amounts of HC and CO

emissions at cold start [4]. Hydrogen is widely regarded as a promising transportation fuelbecause it is clean and renewable. While electrochemically reacting hydrogen in fuel cells is

considered to be the cleanest and most efficient means of using hydrogen, it is believed by many

to be a technology of the distant future. One of the main obstacles that plagued the successfulutilization of hydrogen as a fuel in an ICE has been pre-ignition. This phenomenon is due to theundesirable combustion of the air/fuel charge in the intake manifold [5]. The hydrogen engine is

a possible solution to improving the engine performance at idle and lean conditions. Since the

flame speed of hydrogen is five times as large as that of gasoline, hydrogen engines can get ahigh degree of constant volume combustion which not only benefits the engine thermal

efficiency but also reduces the engine cyclic variation. Besides, the low ignition energy ofhydrogen also permits hydrogen-air mixture to be easily ignited under lean conditions and helps

engines gain a smooth starting process. But increased NOx emissions and reduced power outputof hydrogen engines, it is hard for the pure hydrogen-fueled engines to be widely

commercialized in the near future [6]. The unique combustion characteristics of hydrogen that

allow clean and efficient operation at low engine loads present difficulties at high engine loads.Here, the low ignition energies of hydrogenair mixtures cause frequent unscheduled combustion

events, and high combustion temperatures of mixtures closer to the stoichiometric composition

lead to increased NOxproduction [7]. The main feature of hydrogen as a fuel is that it does notoccur in its free state naturally. Hydrogen can be produced from fossil fuels such as natural gas,

oil and coal, mainly via their reforming with steam or through partial oxidation. Such fuel

mixtures of widely varying composition are processed usually further to increase the purity ofthe hydrogen produced, whether for applications in the chemical and petrochemical industry or

for combustion in conventional power and heating devices. The important application of

hydrogen to fuel cells, ultra-high-purity hydrogen is required which makes the hydrogen

produced by these methods often of unacceptable quality [8].


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2. EXPERIMENTAL SETUP AND METHODOLOGY

2.1 Experimental procedure

To achieve the aim of the experiment the experimental test rig is developed as shown in Fig 1

and its main characteristics are compiled in Table 1

EngineAir cooled, Single cylinder, 4

stroke SI

Bore 70mm

Stroke 66.7mm

Rated power 2.5 kW

Constant speed 3000 rpm

Governor system Centrifugal mechanical

Compression ratio 4.3:1

Table 1: Engine Specifications

It consists of some of the fabrication work for the hydrogen fuel supply. The four stroke single

cylinder is a constant speed engine which runs at 3000 RPM. The governor attached to the

engine regulates the gasoline fuel flow when there is a change in the load and so that the constantspeed is maintained. The load is varied by the hydraulic dynamometer by means of flow control

valve. The fuel flow is measured by means of 50cc burette and air flow by manometer in which

the one end is connected to orifice plate for supplying of hydrogen fuel a separate arrangement ismade and it consists of hydrogen cylinder which consists of hydrogen gas stored at 140 Bars

connected to a surge tank. The Experimental Line diagram and Villiers Engine are shown in Fig

1 and Fig 2 below.

Fig: 1 The experimental line setup diagrams


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(1) Hydrogen gas cylinder at 140 Bars (2) Two stage pressure regulators (3) Non return valve (4)

Surge tank (5) Pressure indicator of surge tank (6) Safety valve (7) Rotameter (8) Line pressure

indicator (9) Carburetor (10) Gasoline tank (11) Orifice plate contained in an air box (12) Engine

cylinder (13) Engine piston connecting rod (14) Hydraulic dynamometer (15) Exhaust manifold(16) K type Thermocouple.

Fig: 2 The Villiers Engine.

The surge tank is three fourth filled with water which prevents the back flow of hydrogen

towards the cylinder in case of back fire. The water in the surge tank quenches the hydrogen.Non Return valve are provided to prevent back fire and back flow of hydrogen into the cylinder

respectively. A hose nipple is brazed to the carburetor holder which is attached to the SI enginecylinder. By means of control valve the hydrogen flow is regulated and passed to the engine

cylinder via inlet manifold. The flow meter shows the volume flow rate of hydrogen. Pressure

indicator and safety valves are also attached to the flame trap. The engine is loaded by adjustingwater flow rate into the hydraulic dynamometer such that the load indicated by the spring

balance. The K type thermocouple is attached to the exhaust pipe of the engine to measure the

exhaust gas temperature. The other end of the thermocouple is connected to the display which inturn connected to the supply. In order to prevent any leakage from the connections from the

cylinder or joints in the surge tank the leak test is made.A hose nipple is attached to the inlet

manifold of carburetor for sending hydrogen , as shown in Fig 3 below.


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Figure 3: Hose nipple attached for hydrogen supply

2.2 Surge Tank design:

The surge tank is a safety feature which is designed to prevent fire from reaching a fuel supplyline as shown in Fig 4 below.

Fig: 4 The Surge tank with hydrogen cylinder.

The surge tank which is a flame trap reduces the risk of explosion or fire, making the systemsafer to operate. It is bent and made cylindrical in shape. The top and bottom side of the cylinder

is bolted. The flame trap is filled half with water and the inlet hose is placed 4 inches above the

ground. The pressure indicator ranging 1 to 10 bars attached to the top of the flame trap. Thestem of the pressure indicator is attached by the means of adopter. The safety valve is also

attached. Any back fire from the engine causes the hydrogen to flow backwards and quench in


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the water. If pressure exceeds 10 bars, then the safety valve will release the surge tank and enters

the outlet and then into the cylinder the non return valve attached near the inlet prevents the back

flow into the cylinder.

3. RESULTS AND DISCUSSIONS

3.1 Brake thermal efficiency:

The Brake thermal efficiency increases as the load increases. The mass flow rate increases as theload increases to maintain the constant speed. The fuel gets utilized properly for combustion at

higher loads due to increase in brake power. As the hydrogen blend increases, the hydrogen has a

much higher diffusion speed than pure gasoline, and reduced combustion period causes the

increase in the specific heat ratio during expansion stroke which increases the brake thermalefficiency. If there is not enough oxygen for proper combustion, the fuel will not burn

completely and will produce less energy. As due to increase in hydrogen blending there will be

good fuel conversion efficiency which reduces the partial burning. One can observe that thebrake thermal efficiency for the 12% hydrogen is the highest and least for the gasoline as shown

in Fig 5 as shown below.

Fig: 5 Variation of brake thermal efficiency with percentage of load for different hydrogen

blends

3.2 Brake specific energy consumption:

The brake specific energy consumption decreases as the load increases. Due to the brake power

developed higher at higher loads, the consumption of fuel per kilowatt hour reduces. The mainreason is that the combustion takes place effectively. Brake specific energy consumption (BSEC)

is a measure of the efficiency of an internal combustion engine. The term specific energy

consumption refers to the amount of energy fuel used normalized to the amount of powergenerated, which gives an efficiency at certain operating point of the engine. The effective

combustion is due to the proper mixing of air and fuel at constant speed and also due to which

also lead in rise of cylinder pressure. This is also due to narrow range of flammability of oxygen

and causes the more fuel to draw in leading to more specific fuel consumption. One can observethat the brake specific energy consumption for gasoline is highest for gasoline and lowest for

12% of hydrogen blend as shown in Fig 6 below.

0

5

10

15

20

25

0 25 50 75 100BrakeThermalEfficiency(%)

Percentage of Load

0 % Hydrogen

3% Hydrogen

6 % Hydrogen

9 % Hydrogen

12 % Hydrogen


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Fig: 6 Variation of Brake specific energy consumption with percentage of load for different

hydrogen blends.

3.3 Volumetric efficiency:

Volumetric efficiency in internal combustion engine design refers to the efficiency with whichthe engine can move the charge into and out of the cylinders. The theoretical energy released

during the combustion process is the product of the mass of fuel contained in the combustionchamber and its heating value if the fuel is completely reacted. The volumetric efficiency

increases as the load increases because the more air is drawn in order to maintain the constant

speed and effective combustion to take place. Even more fuel is drawn inside to maintain

constant speed and in order to supply air to excess fuel more air is drawn in. As the hydrogenblend increases there is a drop in volumetric efficiency. Fuel vapor can take considerably more

of this space, leaving less room for the air being pumped into the cylinder. As a vapor fuel is

burned richer, the fuel takes more space, decreasing the volumetric efficiency. The reason is thatthe hydrogen being lighter than air displaces. This causes less amount of mixture density. In the

Fig 7, one can find that the volumetric efficiency is the highest for the gasoline and lowest forthe 12% hydrogen blend as shown below.

Fig: 7 Variation of Volumetric Efficiency with percentage of load for different hydrogen

blends.

3.4 Exhaust Gas temperature:

5000

15000

25000

35000

45000

55000

0 25 50 75 100

BSEC(

Kj/Kw-Hr)

Percentage of Load

0 % Hydrogen

3 % Hydrogen

6 % Hydrogen

9 % Hydrogen

12 % Hydrogen

25

30

35

40

45

50

55

60

65

0 25 50 75 100

VolumetricEfficiency(%)

Percentage of Load

0 % Hydrogen

3 % Hydrogen

6 % Hydrogen

9 % Hydrogen

12 % Hydrogen


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The Exhaust Gas temperature increases with increase in load. The reason is that the as the load

increases, speed decreases in IC engines. In spark-ignition engines, compression ratios and

therefore the temperatures at the end of compression are low enough that the air-fuel mixture isignited by the spark plug before spontaneous ignition can occur. SI engines are designed so that a

flame front will propagate smoothly from the spark plug into the unburned mixture until all of

the mixture has been ignited. However, as the flame front progresses, the temperature andpressure of the combustion gases behind it rise due to the release of the chemical energy of the

fuel. As the front propagates, it compresses and heats the unburned mixture, sometimes termed

the end-gas. But due to presence of governor the speed tends to remain constant. So in order tomaintain the speed the mass flow rate of the petrol increases. At lower loads the suction pressure

is very low and so the exhaust pressure will be higher and the residual gases do not allow the air

and fuel mixing properly. There will be small amounts of residual gases as the load increases and

combustion takes place effectively. So this is the main reason for the increase in the exhaust gastemperature. Hydrogen presence will make the exhaust gas temperature to rise due to wide range

of flammability and effective combustion. In the Fig 8, one can find that the Exhaust gas

temperature is the highest for the gasoline and lowest for the 12% hydrogen blend as shown

below

.

Fig: 8 Variation of Exhaust gas temperature with percentage of load for different hydrogen

blends.

3.5 Carbon monoxide:

The carbon monoxide increases as the percentage load increases. When there is not enough

oxygen to convert all carbon to CO2, some fuel does not get burned and some carbon ends up as

CO. Not only is CO considered an undesirable emission, but it also represents lost chemical

energy. Maximum CO is generated when an engine runs rich. Rich mixture is required during

starting or when accelerating under load. Poor mixing, local rich regions, and incompletecombustion will also be the source for CO emissions. But as percentage hydrogen blend

increases, there will decrease in the carbon monoxide. The engine will not be capable to utilizethe entire fuel into effective combustion. There will be lubricating oil in the sump which causes

increase in carbon monoxide. The gradual reduction of gasoline flow rate is enforced with

increase in hydrogen blends. This produces shorter post combustion period than gasoline, so thatthe necessary time and cylinder temperature for CO oxidation reaction decreases causing slow

reaction kinetics of CO into CO2. Hydrogen is having higher range of flammability causes the

250

300

350

400

450

500

550

0 25 50 75 100

ExhaustGas

Temperature(C)

Percentage of Load

0 % Hydrogen

3 % Hydrogen

6 % Hydrogen

9 % Hydrogen

12 % Hydrogen


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decrease in CO. In the Fig 9, the CO emission is highest for gasoline and lowest for the 12%

hydrogen blend as shown below

.

Fig: 9 Variation of Carbon monoxide with the percentage of load for different hydrogen

blends

3.6 Unburnt Hydrocarbon:

The unburnt hydrocarbon increases as the percentage load increases. With a fuel rich mixturethere is not enough oxygen to react with all the carbon, resulting in high levels of HC and CO in

the exhaust products. This is particularly true during starting, when the air fuel mixture is

purposely made very rich. It is also true to a lesser extent during rapid acceleration under load. Ifair-fuel ratio is too lean poorer combustion occurs, again resulting in HC emissions. As the lean

flammability limit is approached, combustion quality deteriorates significantly and HC emissions

start to rise again due to the occurrence of occasional partial burning cycles. It is also seen thathydrogen addition decreases the HC emissions. One of the reasons for the decrease in HC

emissions due to hydrogen addition is that hydrogen has a shorter quenching distance thangasoline. A shorter quenching distance allows the flame to travel closer to the cylinder wall

facilitating complete combustion. Another reason is that due to its high diffusivity, hydrogen candisperse into the air more easily, and this facilitates the formation of a more uniform and

homogenous fuel air mixture. Additionally, the high flame speed of hydrogen reduces the

combustion duration, and decreases the probability of occurrence of slow-burning andincomplete combustion cycles. In the Fig 10, the UBHC emission is highest for gasoline and

lowest for the 12% hydrogen blend as shown below.

0

2

4

6

0 25 50 75 100

CO(%V

ol)

Percentage of Load

0 % Hydrogen3 % Hydrogen

6 % Hydrogen

9 % Hydrogen

12 % Hydrogen

200

250

300350

400

450

0 25 50 75 100

UBHC(p

pm)

Percentage of Load

0 % Hydrogen

3 % Hydrogen

6 % Hydrogen

9 % Hydrogen

12 % Hydrogen


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Fig: 10Variation of UBHC with the percentage of load for different hydrogen blends.

3.7 Oxides of Nitrogen:

The oxides of nitrogen increases as the percentage load increases. Most of this will be Nitrogen

oxide (NO) with a small amount of Nitrogen dioxide (NO2). NOx is very undesirable. At lowtemperatures atmospheric nitrogen exists as a stable diatomic molecule N2. Therefore, only very

small trace amounts of oxides of nitrogen are found. The higher the combustion reactiontemperature, more dissociation takes place and more NOx will be formed. At this condition flame

temperature is still high, and in addition, there is an excess of oxygen that can combine with the

nitrogen to form various oxides. Combustion duration also plays a significant role in NO xformation within the cylinder. As the percentage of hydrogen blend increases the NOx increases.

This is because the increase of hydrogen blend will lead to rise in combustion temperature and

wide range of flammability of hydrogen. The Fig 10 shows the nitrous oxide is the highest for

12% hydrogen blend and least for gasoline as shown below.

Fig: 11 Variation of NOx with the percentage of load for different hydrogen blends.4. CONCLUSIONS

The brake thermal efficiency increases as percentage of hydrogen blend increases. Thereis an average increase of 6.32%, 10.8%, 14.63% and 17.8% for the hydrogen blend of3%, 6%, 9% and 12% respectively with respect to gasoline.

The brake specific energy consumption decreases as the percentage of hydrogen blendincreases. There is a an average decrease of 15.66%,21.32%,28.72% and 36.34% for thehydrogen blend of 3%,6%,9% and 12% respectively with respect to gasoline.

The volumetric efficiency decreases as the percentage of hydrogen blend increases. Thereis an average decrease of 6.15%, 11.22%, 18.23% and 24.36% for the hydrogen blend of

3%, 6%, 9% and 12% respectively with respect to gasoline. The carbon monoxide decreases as the percentage of hydrogen increases. There is an

average decrease of 11.38%,20.56%,28.67% and 38 43% for the hydrogen blend of 3%,

6%, 9% and 12% respectively with respect to gasoline.

The Unburnt hydrocarbon decreases as the percentage of hydrogen blend increases. Thereis an average decrease of 8.82%, 14.47%, and 24.05% for the hydrogen blend of 3%, 6%,

9% and 12% respectively with respect to gasoline.

-30

20

70

120

0 25 50 75 100

NOx(ppm)

Percentage of Load

NOx Vs Load

0 % Hydrogen

3 % Hydrogen

6 % Hydrogen

9 % Hydrogen

12 % Hydrogen


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The NOx increases as the percentage of hydrogen blend increases. There is an averageincrease of 17.92%, 32.56%, 50.61% and 61.2% for the hydrogen blend of 3%, 6%, 9%

and 12% respectively with respect to gasoline. From the experiment that was conducted, one can conclude that the engine goes towards

lean mixture. This is because of higher flammability of hydrogen and higher diffusion

speed.

ACKNOWLEDGEMENT

Authors whole heartedly thank the NITK Surathkal institution for providing financial support.

REFERENCES

[1] Erol Kahramana, S. Cihangir Ozcanlb, Baris Ozerdemb (2007), An experimental study onperformance and emission characteristics of a hydrogen fuelled spark ignition engine,

International Journal of Hydrogen Energy, vol. 32, P 2066 2072.

[2] Changwei Ji, Shuofeng Wang (2009), Effect of hydrogen addition on combustion andemissions performance of a spark ignition gasoline engine at lean conditions, International

journal of Hydrogen Energy, vol. 34, P 823-7834.

[3] Farhad Salimi, Amir H. Shamokin, Ali M. Pourkhesalian (2009), Role of mixture richness,

spark and valve timing in hydrogen-fuelled engine performance and emission InternationalJournal of Hydrogen Energy, vol. 34, P 3922-3929.

[4] Shuofeng Wang, Changwei Ji, Bo Zhang (2011), Starting a spark-ignited engine with the

gasoline hydrogen mixture, International Journal of Hydrogen Energy, vol. 36, P 4461-4468.

[5] James W. Hewel (2003), NOx emission and performance data for a hydrogen fueled internal

combustion engine at 1500 rpm using exhaust gas recirculation, International Journal of

Hydrogen Energy, vol. 28,P 901-908.[6] Changwei Ji, Shuofeng Wang (2010), Combustion and emissions performance of a hybrid

hydrogengasoline engine at idle and lean conditions, International Journal of Hydrogen

Energy, vol. 35, P 346-355.[7] C.M. White, R.R. Steeper, A.E. Lutz (2006), The hydrogen-fueled internal combustion

engine: a technical review, International Journal of Hydrogen Energy, vol. 31, P 1292-1305.

[8] Ghazi A. Karim (2003), Hydrogen as a spark ignition engine fuel International ofHydrogen Energy, vol. 28, P 569-577.


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AUTHORS

Suhas B.G received his B.E degree from PESIT, Bangalore under VTU

university. Now he is pursuing M Tech degree in Thermal Engineering fromNITK, Surathkal. His research interest is IC engines.

Shivaprasad K.V received his B.E degree from Malnad college of

engineering, Hassan under VTU university, M Tech degree in Energy

System Engineering from NITTE, Karkala under VTU university. Now he ispursuing Ph.D degree in NITK, Surathkal. His research interests are

Renewable energy and IC engines.

Kumar G.N received his M Tech degree in Heat Power Engineering at

NITK, Surathkal and Ph.D degree from Indian Institute of Technology,Delhi. He is currently working as Assistant Professor at NITK, Surathkal. He

has served as an organizer for several National and International conference.

His research interests are IC engines, Renewable energy and Heat transfer.

Experimental Investigation of Single Cylinder 4s Si Engine With Hydrogen Blends

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