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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.