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CHAPTER 5
EXPERIMENTAL SET UP AND
TESTING PROCEDURES
5.1 OBJECTIVES
To find the suitability of METPSO as a fuel in CI engine, following
experimental techniques are adopted.
1. Regular experiments on a computerized diesel engine. i.e.,
Performance and combustion characteristics of an engine
fueled initially with diesel and followed by METPSO and its
blends.
2. Exhaust gas analysis (CO, CO2, HC, NOx, O2 and Smoke
intensity).
3. Effect of injection timing and injection pressure on neat
METPSO fueled CI engine to determine the optimum
condition.
4. Experiment on peroxidized METPSO fueled CI engine.
5. Effect on EGR on CI engine performance and emission.
6. Effect of compression ratio on CI engine performance and
emission characteristics.
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5.2 EXPERIMENTAL TEST SET UP
A 3.5 kW, 1500 rpm, Kirloskar diesel engine is used in this
investigation as shown in Figure 5.1. The detailed specification given in
Table 5.1. Two separate fuel tanks with a fuel switching system are used, one
for diesel (D100) and the other for biodiesel (B100). Fuel consumption is
measured using optical sensor. A differential pressure transducer is used to
measure airflow rate. Engine is coupled with an eddy current dynamometer to
control engine torque through computer. Engine speed and load are controlled
by varying excitation current to eddy current dynamometer using
dynamometer controller. A piezoelectric pressure transducer is installed in
engine cylinder head to measure combustion pressure. Signals from pressure
transducer are fed to charge amplifier. A high precision crank angle encoder is
used to give signals for top dead centre and crank angle. The signals from
charge amplifier and crank angle encoder are supplied to data acquisition
system. An AVL exhaust gas analyzer and AVL smoke meter are used to
measure emission parameters and smoke intensity respectively.
Thermocouples (chrommel alumel) are used to measure exhaust temperature,
coolant temperature, and inlet air temperature.
Figure 5.1 Experimental setup
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5.3 INSTRUMENTATION DETAILS
5.3.1 Eddy Current Dynamometer
An eddy current dynamometer of 3.5 kW (1500 rpm) capacities is
directly coupled with the engine. The engine and air cooled eddy current
dynamometer are coupled using tyre coupling. The output shaft of the engine
is connected to the dynamometer through a torque transducer for measuring
torque. A torque transducer provides an electrical signal that is proportional to
torque. A load cell is an electronic device (transducer) that is used to convert
a force into an electrical signal. The load to the engine can be varied by
operating the potentiometer provided on the panel or through computer.
5.3.2 Air Flow Sensor
The air flow to the engine is routed through cubical air tank. The
rubber diaphragm fixed on the top of the air tank takes care of neutralizing the
pulsation for airflow measurement. The inlet air tank is provided with an
orifice. The differential pressure of air was measured in the computer using a
differential pressure transducer (0-99 m3/hr) calibrated to indicate volume
airflow. The pressure ports are connected to instrumentation panel using
smooth flexible hose.
The pressure drop across the orifice is measured using a differential
pressure transducer. The output of the differential pressure transducer is
amplified using an instrumentation amplifier and fed to the data acquisition
card. The differential pressure sensor use state of the art silicon micro
machined pressure sensor in conjunction with stress free packaging
techniques to provide highly accurate, amplified, calibrated and temperature
compensated pressure readings.
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5.3.3 Fuel Flow Sensor
The fuel from the tank was connected by way of a solenoid valve to
a glass burette and the same is connected to the engine through a manual ball
valve. The fuel solenoid of the tank will open and stay open for 30sec, during
this time fuel is supplied to the engine directly from the fuel tank and also fills
ups the burette. After 30 sec the fuel solenoid closes the fuel tank outlet, and
now the fuel in the burette is supplied to the engine.
When the fuel level crosses the high level optical sensor, the
sequence running in the computer records the time of this event. Like wise
when the fuel level crosses the low level optical sensor, the sequence running
in the computer records the time of this event and immediately the fuel
solenoid opens filling up the burette and cycle is repeated. Now, volume of
the fuel between high level and low level optical sensors (20 cm3) is known.
The starting time of fuel consumption, i.e. time when fuel crossed high level
sensor and the finish time of fuel consumption, i.e. time when fuel crossed
low level sensor gives an estimate of fuel flow rate i.e., 20 cm3/difference of
time in sec.
5.3.4 Speed Sensor
A non contact PNP sensor (0-9999 rpm) is used to measure the
engine speed. A PNP sensor gives a pulse output for each revolution of the
crankshaft. The frequency of the pulses is converted into voltage output and
connected to the computer.
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5.3.5 Load Cell (Torque Measurement)
Torque is measured using a load cell transducer (0-100 kgs). The
transducer is strain gauge based. The output of load cell is connected to the
load cell transmitter. The output of load cell transmitter is connected to the
USB port through interface card.
5.3.6 Temperature Sensors
K-type thermocouples are located at appropriate places to measure
the following temperatures. The output of the temperature transmitters is
connected to data acquisition card.
Combustion peak temperature
Inlet water temperature in calorimeter
Outlet water temperature in calorimeter
Inlet exhaust gas temperature in colorimeter
Outlet exhaust gas temperature in colorimeter
Inlet water temperature to the engine cylinder
Outlet water temperature from the engine cylinder
Lube oil temperature
5.3.7 Pressure Sensor
Piezoelectric transducer (water-cooled type) is used to measure
cylinder pressure.
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5.3.8 Crank Angle Encoder
11 bit 2050 step crank angle encoder (Air-cooled type) is mounted
on the cam shaft to measure engine crank angle. The crank angle encoder
contains a precision maker disk with a trigger mark and 360o angle marks
which are scanned by a transmission photoelectric cell encased in a dust proof
housing. It is powered by a 24V DC power supply and supplies one
corresponding analog output between 0o and 360o.
5.3.9 Analog to Digital Converter (ADC)
An ADC/data acquisition system (12-bit) captures data about an
actual system and stores that information in a format that can be easily
retrieved for purposes of engineering or scientific review analysis. Another
requirement of a data acquisition system should be that it captures
information programmatically or automatically – in other words, without any
hands-on human intervention or guidance. The seven key functions of the data
acquisition systems are follows:
Data collection
Measurement
Trimming and triggering
Real time clock
System control
Data communication
Data retrieving
All seven elements must be in place for a structure to be considered
a data acquisition system. There must be a series of sensors (input channel) to
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a data acquisition board. In addition, there must be a trigger to synchronize
the sensors inputs, as well as a control for the data acquisition board. Between
data acquisition board and processor of the system and system clock, a data
communications bus is also required. While data being stored real-time, the
analysis and review of the information is performed after data is gathered.
Table 5.1 Engine Specifications
Make Kirloskar –TV1
Power and Speed 3.5 kW and 1500 rpm
Type of engine Single cylinder, DI and 4 Stroke
Compression ratio 16.5:1
Bore and Stroke 80 mm and 110 mm
Method of loading Eddy current dynamometer
Method of starting Manual cranking
Method of cooling Water
Type of ignition Compression ignition
Inlet valve opening 4.50 before TDC
Inlet valve closing 35.50 after BDC
Exhaust valve opening 35.50 before BDC
Exhaust valve closing 4.50 after TDC
Fuel injection timing 230 before TDC
Nozzle opening pressure 210 bar
Lube oil SAE40
5.3.10 Emission Analyzer
Smoke meter as shown in Figure 5.2 is used to measure the
intensity of smoke present in the exhaust gas and the specification of the
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smoke meter is given in Table 5.2. Gas analyzer as shown in Figure 5.3 is
used to measure the CO, CO2, HC, NOx and O2 present in exhaust gas. This
analyzer consists of four detectors namely, Non-Dispersive Infrared Detector
(NDIR) which detects CO and CO2 emission, Chemiluminiscence Detector
(CLD) which detects NOx emission, Flame Ionization Detector (FID) which
detects HC emission and Lambda sensor which senses the O2. Specification of
the gas analyzer is given in Table 5.3.
Table 5.2 Smoke meter specifications
Model AVL 437
Measuring range 0-100 opacity in %
0-99.99 absorption m-1
400….6000 min-1
0…150˚C
Accuracy and reproducibility ±1% Full scale reading
Max smoke temperature at entrance 250˚C
Table 5.3 Gas analyzer specifications
Type AVL DiGas 444
Measured quality Measuring range
CO 0… 10 % vol
CO2 0… 20 % vol
HC 0… 20000 ppm
O2 0… 22 % vol
NOx 0… 5000 ppm
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Figure 5.2 Photographic view of smoke meter
Figure 5.3 Photographic view of five gas analyzer
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The accuracy of measurement and uncertainities of computed
results are listed in Table 5.4.
Table 5.4 Accuracy of measurement and uncertainties of computed
results
Measurements Accuracy NOx ±5 ppm CO ± 5% of indicated value CO2 ± 5% of indicated value HC ± 1 ppm Smoke ± 1% full scale reading O2 ± 5% of indicated value Temperatures ± 1oC Dynamic viscosity ± 1% Calorific value ± 1% Specific gravity ± 1% Computed Results Uncertainty (%) Kinematic viscosity ± 1.3% Brake Power 0.5% BSFC 1.5% Total Fuel flow 1% Brake Thermal efficiency 1% Speed ± 3 rpm
5.4 EXPERIMENTAL PROCEDURE
5.4.1 Base Line Testing
The flow of air, the level of lubricating oil and the fuel level
are checked before starting the engine.
The engine is cranked by keeping the decompression lever and
the fuel cut off lever of the fuel pump in the ON position.
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When the engine starts, the decompression lever is disengaged
and the speed of the engine is increased to 1500 rpm and
maintained.
The engine is allowed to run for 15 minutes to reach the
steady state conditions.
The time taken for 20 cm3 of fuel consumption for every load
charge is recorded.
Under each load, by the exhaust gas analyzer, CO, CO2, HC,
O2, NOx, and by smoke meter, intensity of smoke and exhaust
gas temperature are measured and recorded.
5.5 EXPERIMENTAL DETAILS
There are seven major experiments conducted to predict
performance, combustion and emission characteristics of compression
ignition engine fueled with Thevetia Peruviana seed oil.
To find the suitability and feasibility of METPSO as a fuel in diesel
engine the following experiments have been conducted.
1. Experiments on the CI engine fueled with blends and neat
METPSO: Engine performance characteristics are the major criterion that
governs the suitability of a fuel. The purpose of this study is to investigate the
performance and exhaust emissions of various blends of METPSO in the
computerized diesel engine and to compare them with that of D100. The
METPSO has been blended with D100 in several percentages (20%, 40%,
60% and 80%) and are named as B20, B40, B60 and B80. Next METPSO is
also taken up for testing (B100). The acquisition of operating parameters such
as performances and emission characteristics, as a function of brake power is
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done, at the engine speed of 1500 rpm. The effect of blends of METPSO on
the following parameters have been investigated and discussed in this study.
Brake specific fuel consumption
Brake thermal efficiency
Carbon monoxide
Carbon dioxide
Unburned hydrocarbon
Nitrogen oxide
Exhaust smoke
Exhaust gas temperature
2. Combustion characteristics of a CI engine fueled with
blends and neat METPSO: The following parameters are measured and
analyzed with diesel and blend of METPSO with diesel as fuel.
Cylinder pressure variation with crank angle and load.
Instantaneous heat release rate.
Cumulative heat release.
Ignition delay.
Rate of pressure rise.
Combustion duration.
3. Performance and emission studies with other non-edible
and edible oil based biodiesel and diesel blends with blend ratios of 20%
and 100% and comparison made with that of METPSO: For making
comparison of neat METPSO and 20% blend with other non-edible and edible
based biodiesel of the same blend level, performance and emission studies
were carried out on the same engine. The engine is run at a constant speed of
1500 rpm. Load is changed in eight levels from no load to maximum load
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condition. For better clarity, results are presented and discussed only at no
load, part load (1.75 kW) and maximum load (3.5 kW) conditions.
MEJO
MEPO
MEMO
MENO
MECO
MEPaO
MECoO
MEMuO
MESO
MERO
All the above methyl esters are prepared in our laboratory and
properties such as kinematic viscosity, specific gravity, calorific value, flash
pint, fire point, cloud point and pour point are found as per the ASTM
standards. The properties of above said methyl ester is listed in the Annexure-
1and compared with diesel and METPSO.
4. Experiments to find out the optimum injection timing and
optimum injection pressure for neat METPSO: Experiments are conducted
at a constant speed of 1500 rpm under variable load conditions with diesel
and neat METPSO. Parameters like Injection timing and injector opening
pressure are varied incase of neat METPSO to study their influence on
performance and emission. Results have been compared with neat diesel
operation (23obTDC and 210 bar). The injection timing is varied (23o, 25o 27o
and 29o bTDC) by changing the position of fuel injection pump with respect
to the cam. Subsequently, injection pressure is varied (210, 215, 220, 225, 230
and 235 bar) by adjusting the screw of injector.
Non- Edible Oil
Edible Oil
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5. Experiments with peroxidized biodiesel for further
improvement of performance and emission: METPSO obtained from
transesterification process is further improved by peroxidation technology. In
using this technology, 2% and 4 % (by vol.) of hydrogen peroxide (H2O2) is
then added with METPSO and stirred in the reactor tank at 600C. The reaction
time of this peroxidation process is 10 – 15 min. Afterwards, the un-reacted
impurities and methanol are removed by a distillation method and peroxidized
biodiesel is obtained. Properties of peroxidized biodiesel and neat biodiesel
are shown in Table 5.5.
Table 5.5 Properties of peroxidized fuel
Property METPSO B100(2%P) B100(4%P) ASTM code
Calorific value, kJ/kg 40462 40232 39990 D4809
Specific gravity 0.839 0.842 0.846 D445
Viscosity (at 400C)cSt 4.2 4.4 4.5 D2217
Cetane number 49 50 50 D4737
Flash point, °C 110 117 124 D92
Fire point, °C 120 125 131 D92
Cloud point, °C -4 -5 -5 D97
Pour point, °C -10 -9 -10 D97
Ash content, % 0.003 0.002 0.002 D976
Vegetable oil, biodiesel and peroxidized biodiesel are then tested
for their performance in a diesel engine and for their emission characteristics.
The engine experiments are carried out in the same engine under constant
speed at 1500 rpm and varying the engine load. Each experiment is repeated
three times to calculate the mean value of the experimental data. Obtained
performance and emission parameter are plotted in bar chart.
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6. Performance and emission characteristics studies with
different rates of Exhaust Gas Recirculation to reduce the NOx emission:
Exhaust gas circulation is an effective method for NOx control. The exhaust
gases mainly consist of carbon dioxide and nitrogen and possess high specific
heat. When recirculated into the engine inlet, it acts as a heat sink. This
process reduces oxygen concentration and peak combustion temperature,
which results in reduced NOx.
Exhaust gas is tapped from pipe and connected to inlet air flow
passage. An EGR control valve is provided in this pipe for EGR control
(Figure 5.4). The gas inlet volume is controlled by this valve and directly sent
to the inlet manifold without a gas cooler. Sufficient distance for thorough
mixing of fresh air and exhaust gas is ensured. Temperature of the mixture
(exhaust gas and fresh air) is measured just before its entry into the
combustion chamber using a K-type thermocouple. EGR amount is
determined using an expression,
The effect of different percentage of EGR on Performance and
emission characteristics of same engine fueled with METPSO is studied. All
the experiments are conducted at variable engine load condition and a
constant speed of 1500 rpm.
Mass of air admitted without EGR- Mass of air admitted with EGR % of EGR = Mass of air admitted without EGR
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Figure 5.4 Exhaust gas recirculation piping
7. Experiments on a Variable Compression Ratio engine to
predict the optimum compression ratio of neat methyl ester for
METPSO: This experiment is aimed to study the effect of compression ratio
on performance and emission characteristics in a separate variable
compression ratio diesel engine (2.3 kW). The detailed specification of engine
is listed in Table 5.6 and the VCR engine setup photograph is shown in Figure
5.5. Initially, base line experiments are conducted in the VCR engine fueled
with diesel for various compression ratios (14.5, 15.3, 16.1, 17.0, 18.1, 19.2
and 20.6) at a constant speed of 1500 rpm and by varying the load in six
levels from no load to maximum load. Subsequently, engine is operated with
neat METPSO for same condition. The performance and emission
characteristics like brake thermal efficiency, brake specific fuel consumption,
exhaust gas temperature, CO, CO2, HC, NOx, O2 and smoke intensity are
measured and compared to that of diesel. From the obtained results, optimum
compression ratio is determined for METPSO fuel.
ENGINE
Exhaust Gas
Air vessel
Air Flow meter
EGR Valve
Mixture of Air and Exhaust Gas
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Figure 5.5 Variable compression ratio diesel engine set up
Table 5.6 Specification of the VCR engine
Make Kirloskar TV1
Power 2.3 kW
Speed 1500 rpm
No of cylinder Single cylinder
No of stroke Four stroke
Type of Engine DI, Naturally aspirated
Compression Ratio 14.5:1 to 20.6:1
Bore and Stroke 85 mm and 82 mm
Method of loading Eddy current dynamometer
Method of starting Manual cranking
Method of cooling Water
Injection pressure 210 bar
Injection timing 230 bTDC
Lube oil SAE 40
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All the readings have been taken after reaching the steady state.
Every experiment has been conducted at eight levels of loading from no load
to maximum load. But the results have been discussed with three loading
conditions only namely; no load, part and maximum load to avoid the graphs
from getting clustered.
The engine is operated at 1500 rpm for all tests. Special care is
taken to maintain steady state condition for every reading. Performance and
emission parameters like brake thermal efficiency, brake specific fuel
consumption, volumetric efficiency, mechanical efficiency, CO, CO2, NOx,
O2, HC, smoke intensity and exhaust gas temperature are measured, compared
and analyzed.
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