CHAPTER 4 EXPERIMENTAL INVESTIGATION - …shodhganga.inflibnet.ac.in/bitstream/10603/11547/9/09...45...
Transcript of CHAPTER 4 EXPERIMENTAL INVESTIGATION - …shodhganga.inflibnet.ac.in/bitstream/10603/11547/9/09...45...
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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