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CHAPTER 4

EXPERIMENTAL INVESTIGATION

4.1 TEST ENGINE

The experiments were carried out in a four cylinder, four-stroke

water-cooled turbocharged DI diesel engine. The engine specifications are

given in Appendix 1 and the material properties of engine combustion

chamber and ceramic coating are given in Appendix 2. The power developed

by the engine was measured by using an eddy current dynamometer at

different speeds and loads. The specification of the eddy current

dynamometer is given in Appendix 3. Figure 4.1 shows the photographic

view of the test engine.

Figure 4.1 Photographic view of test engine

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Fuel consumption was measured using fuel measuring burette by

noting the time taken for 50 cc fuel consumption. Mass of air flow for

different speed and load was measured using air box method fitted with an

orifice plate and a simple U tube water manometer to note down the head

difference. The exhaust gas temperature before and after the turbine was

measured using iron-constantan thermocouple. A mercury-in-glass

thermometer was used to measure the cooling water inlet and outlet

temperatures. The exhaust emission measurement instrument includes smoke

meter and exhaust gas analyzer. Calibration of each analyzer was done before

each test. Using the appropriate calibration curve, the measurement error for

each analyzer was reduced to less than 2%, as recommended in the exhaust

analyzer bench manual. The emission data were expressed as ‘‘brake

specific’’ basis (g/kWh) except for the Bosch smoke number (BSN). The

specifications of the smoke meter and exhaust gas analyzer are given in

Appendix 4 and Appendix 5 respectively.

4.2 MEASUREMENT SYSTEM

4.2.1 Crank Angle Pulse Generating System

The crank angle pulse generating system consisting of a pulse-

generating wheel, intended to make a pulse for every 10 degrees of crank

rotation because of the experimental facility which helps to draw the more

accurate heat release diagram from cylinder pressure. To distinguish the TDC

and BDC position, three teeth at 5-degree gaps were provided diametrically

opposite on the wheel. All other teeth were at

10-degree interval. A magnetic pick up was mounted near the pulse-

generating wheel to sense the crank angle position. On rotation of the pulse

generating wheel the signal generated is fed into one of the channel to the

storage oscilloscope for storing and subsequently for transferring it to a

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personal computer for plotting the cylinder pressure with respect to crank

angle.

4.2.2 Cylinder Pressure Measurement System

The experimental setup along with instrumentation system for the

measurement of cylinder pressure is shown in Figure 4.2. A piezo electric

pressure transducer fitted with an adopter was screwed on to a tapped hole on

the cylinder head is shown in Figure 4.3. The piezo electric crystal produces

an electric charge proportional to the pressure inside the combustion chamber,

and this electric charge is fed to a charge amplifier for conditioning and

conversion into equivalent mechanical units. The output signal from the

charge amplifier is fed in to one channel of the storage oscilloscope for

storing and transfers it to a personal computer for plotting.

Figure 4.2 Experimental set up

1. Turbocharged engine 2. Dynamometer

3. Turbocharger setup 4. Exhaust gas analyzer

5. Air box fitted with intake manifold 6. Piezo electric transducer

7. TDC position sensor 8. Charge amplifier

9. CRO connected with position sensor 10. Computer

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Figure 4.3 Piezo electric pressure transducer fitted on cylinder head

4.3 MODIFICATION OF CONVENTIONAL TURBOCHARGED

ENGINE (CTC) TO LHR TURBOCHARGED ENGINE (LTC)

The conventional turbocharged engine was modified to LHR

turbocharged engine by coating partially stabilized zirconia (PSZ) of 0.5 mm

and 1 mm thickness on outside of cylinder liner, cylinder head with valves

and piston top. Figure 4.4 shows the photographic view of the uncoated

cylinder components. Figure 4.5 – 4.9 shows the photographic view of

cylinder liner, piston, cylinder head and valves coated with 0.5 mm and 1 mm

thickness. Figure 4.10 shows the photographic view of the ceramic coated

engine components fitted in to the test engine.

Figure 4.4 Photographic view of engine components without ceramic

coating

Piezo electric

pressure transducer

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Figure 4.5 Photographic view of cylinder liner with 0.5 mm ceramic

coating thickness

Figure 4.6 Photographic view of piston top with 0.5 mm ceramic

coating thickness

Figure 4.7 Photographic view of cylinder head with valves with 0.5 mm

ceramic coating thickness

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Figure 4.8 Photographic view of cylinder liner with 1 mm ceramic

coating thickness

Figure 4.9 Photographic view of piston, cylinder head and valves with

1 mm ceramic coating thickness

Figure 4.10 Photographic view of engine components fitted in to the test

engine

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4.4 FUEL PREPARATION

Jatropha biodiesel produced through transesterification process was

used as fuel in the test engine. Various proportions of Jatropha biodiesel

blended with diesel are used in test engine, viz, 10% of biodiesel is mixed

with 90% of diesel by volume is referred as B10 (generally referred as BXX).

4.5 FUEL PROPERTIES

The physical and fuel properties of diesel, straight vegetable oil

(SVO), various ratio of biodiesel blends are summarized in Table 4.1.

Table 4.1 Properties of Diesel, Straight Vegetable Oil (SVO), Biodiesel

(B100), 10% biodiesel with diesel (B10), 20% biodiesel with

diesel (B20), 30% biodiesel with diesel (B30)

Properties Diesel SVO B100 B10 B20 B30

Density @ 15 C(kg/m3) 830 917 880 835 840 845

Viscosity @ 40 C(cSt) 2.8 36 4.6 2.95 3.15 3.35

Flash point ( C) 55 229 170 69 80 90

Cetane number 45 45 50 45.5 46 47

Lower Heating Value (MJ/kg) 42 36 39 41.7 41.3 41

4.6 EXPERIMENTAL PROCEDURE

Experiments were conducted in the conventional turbocharged

engine (denoted by CTC) and LHR turbocharged engine (denoted by LTC)

using diesel (denoted by DF) and various biodiesel blends (denoted by BXX).

i) The engine was tested under full load condition for different

speeds viz. 1000, 1100, 1200, 1300, 1400 and 1500 rpm.

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Since the engine’s rated speed is only 1500 rpm, the readings

were taken at the step of 100 rpm increment.

ii) The time for 50 cc of fuel consumption was noted down for

each load and speed condition.

iii) The mass flow rate of air was estimated by using a water

manometer, air drum and an orifice plate arrangement.

iv) The cylinder peak pressure was measured by using the Piezo

electric pressure transducer, charge amplifier, and storage

oscilloscope arrangement.

v) The emission level in the exhaust gas was measured by using

the exhaust gas analyzer.

vi) The experimental engine components such as cylinder head

with valves, outer surface of the cylinder liner and the piston

top surface were coated with partially stabilized zirconia of

0.5 mm and 1 mm thickness.

vii) After fitting the ceramic-coated components in the engine the

experiments were carried out under identical operating

conditions.

viii) Each test was repeated 3 times and averaged to decrease the

uncertainty.

ix) The accuracy and uncertainty of the instruments and

measurements are maintained to fall well within the

acceptable standards and limits.

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4.7 ACCURACY AND UNCERTAINTY OF EXPERIMENTAL

RESULTS

The accuracy of measuring instruments such as loading devices

(dynamometer), exhaust gas analyzer, speed measurements, temperature

measurements (exhaust gas temperature), pressure measurements and fuel

consumption (burette) are given in Table 4.2.

Table 4.2 Accuracy of measuring instruments

Sl.No. Instruments Range Accuracy

1 Exhaust gas analyzer NOx : 0 - 5000 ppm

UBHC: 0 -10,000 ppm

CO2 :0 - 20%

CO :0 - 10%

10 ppm

20 ppm

0.03%

0.02%

2 EGT Indicator 0 - 900°C 1°C

3 Speed measuring unit 0 - 10000 rpm 10 rpm

4 Digital stop watch - 0.5 s

5 Manometer 0 - 500 mm 1 mm

6 Burette for fuel measurement 0 - 100 cc 0.1 cc

7 Pressure pick up 0 - 110 bar 1 bar

8 Crank angle encoder - 1°

9 Dynamometer 0-1000 Amps 0.1 %

The uncertainties of the various calculated values such as brake

power, torque, brake thermal efficiency and brake specific fuel consumption

are presented in Table 4.3.

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Table 4.3 Uncertainty of computed parameters

Sl.No. Calculated parameters % Uncertainties

1 Brake Power 2.1 %

2 Torque 1.6 %

3 Brake thermal efficiency 2.2%

4 Brake specific fuel consumption 1.4 %

Table 4.4 Test matrix (experimental) for combustion, performance and

emission study on conventional turbocharged and LHR

turbocharged DI diesel engine

Parameter Types of Engine Details of fuel used

Blend ratio Conventional Turbocharged engine

at full load

Diesel, B20

LHR turbocharged engine at full

load (0.5 mm coating thickness)

Diesel, B10, B20, B30

LHR turbocharged engine at full

load (1 mm coating thickness)

Diesel, B10, B20, B30

Speed Conventional Turbocharged engine

at full load speed ranging from

1000 to 1500 rpm with 100 rpm

increase.

Diesel, B20

LHR turbocharged engine (0.5 mm

coating thickness) at full load speed

ranging from 1000 to 1500 rpm

with 100 rpm increase.

Diesel, B10, B20, B30

LHR turbocharged engine

(1 mm coating thickness) at full

load speed ranging from 1000 to

1500 rpm with 100 rpm increase.

Diesel, B10, B20, B30

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In this experimental and theoretical analysis, the following

variables were studied and compared as and when possible to validate the

prediction capability of the model.

1. Cylinder pressure

2. Burning zone temperature

3. Cylinder mean temperature

4. Heat release rate

5. Cumulative heat release

6. Cumulative work done

7. Convective heat transfer

8. Radiative heat transfer

9. Total heat transfer

10. Heat transfer coefficient

11. Brake power

12. Brake thermal efficiency

13. Specific fuel consumption

14. Volumetric efficiency

15. Hydrocarbon emission

16. Carbon monoxide

17. Oxides of nitrogen

18. Smoke emission