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1 Lab T1: Compression Ignition (Diesel) Engine Lab Instructor: M.reza(Mamzi) Naghash Location: 1B30

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2 Objectives To become familiar with the operation of a compression-ignition (diesel) engine To determine the effect of load variation at constant speed on –Mechanical efficiency –The primary characteristics of in-cylinder pressure development To perform an energy balance on the engine

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3 Piston at bottom dead center (BDC), cylinder volume greatest. Piston at top dead center (TDC), cylinder volume least Compression Ratio = Volume A / Volume B Swept Volume = Volume A – Volume B Engine Nomenclature Valves Cylinder Piston Crankshaft Connecting Rod Fuel Injector

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4 Operation of a 4 stroke compression ignition engine A C

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5 D C

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6 D C E C to E is called the Compression Stroke

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7 Operation of a 4 stroke compression ignition engine G E E to G is called the Power Stroke F – Power Stroke

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8 Operation of a 4 stroke compression ignition engine G A

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10 Injector Needle Lift and Fuel Line Pressure Fuel Injection Pump Rack Injector Cam at ½ Engine Speed Rotate Shaft to Adjust Fuel Supply P fuel Displacement Transducer Injector Needle Fuel Spill Port

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11 Petter Diesel Engine Injector Pump HELIX (The position of the helix to the fuel spill port meters the amount of fuel delivered to the injector by changing the effective stroke of the pluger.) FUEL SPILL PORT FUEL SUPPLY PORT PLUNGER

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12 In Lab Procedure Collect data at four operating points. –Constant RPM (N=1050 RPM) –Increase fuel injection and obtain N=1050 by increasing load At each operating point –Await steady state (exhaust gas temp.) –Fill out data sheets –Capture P cyl and V vs time waveform on oscilloscope At intermediate operating point (3 rd operating point) –4 P cyl and V vs. time for single cycles –Injector needle lift, P fuel, P cyl, vs time

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13 Calculations and Discussion 1.Brake Power 2.Indicated Power a)Need to plot P-V diagrams for each load 3.Specific Fuel Consumption 4.Volumetric Efficiency 5.Air/Fuel Ratio 6.Mechanical Efficiency 7.Brake Thermal Efficiency 8.Mass flow rate of Exhaust 9.“Willans Line” Test 10.Energy Balance 11.Plot a P cyl and V vs. t diagram for a cycle at the 3 rd load condition 12.P cyl vs. t for 4 cycles at 3 rd test condition 13.V vs. t for 4 cycles at 3 rd test condition 14.Plot injector needle lift, fuel line pressure, and P cyl vs. time 15.Plot the first derivative of P cyl on a P cyl vs. t diagram Preliminary Discussion Operation of fuel injector pump Timing of fuel pressure, injector needle lift, pcyl Discuss Signals on the scope Predictions of how performance measures will change between operating points How does the data differ from the idealized Diesel cycle (what assumptions are not valid in a real engine)

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14 1. Brake Power Rotational speed of engine [rev/s] Brake load [N]Load arm radius [m]

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15 3. Specific Fuel Consumption Fuel consumption (kg/h) Brake Power

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16 4. Volumetric Efficiency Orifice coefficientOrifice area Differential pressure across Orifice (Pa) Ambient

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17 5. Air/Fuel Ratio

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18 6. Mechanical Efficiency Brake Power Indicated Power

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19 7. Brake Thermal Efficiency Lower heating value for fuelMass flow rate of fuel

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20 8. Mass Flow Rate of Exhaust Conservation of Mass

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P cyl and V vs. t Label the four strokes on a P cyl and V vs. t diagram for one of the four cycles observed at the 3 rd test condition. P V

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Injector Needle Lift, Fuel Line Pressure, and P cyl vs. t Plot injector needle lift, fuel line pressure, and P cyl vs. time on a single plot. Comment on the relationship between these three. (Focus on the order and timing of when things occur).

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Calculate the first derivative of in-cylinder pressure for ONE cycle taken at the 3 rd load condition. Plot it on the corresponding P cyl vs. time diagram and comment on the relationship of this graph to the operation of the engine.

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What do we want in our logbook: Explain a summary of experiment Explain about general operation of injector pump. Thermodynamic cycle and changes in pressure and volume What is the relation between of fuel injection, combustion and rate of change in pressure in cylinder. Fill data sheet completely. 24

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25 2. Indicated Power: Proportional to the area within the power and compression strokes minus the area within the intake and exhaust strokes. Area within intake and exhaust strokes is very small and can be neglected! Only 2 of 4 strokes considered Area under P-V

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26 Step 1: Plot P-V Diagram

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27 Offseting: Find the minimum data

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PV diagram with offsets 28

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Filtering: Modifying data 29

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30 P-V Diagram after Offsets and Filtering

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31 Indicated Power

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32 Indicated Power Indicated Mean Effective Pressure Why N/2 ?

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33 Numerical Integration 1 2

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34 Numerical Integration

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35 Indicated Mean Effective Pressure

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36 9. Willans Line for Mechanical Losses Fuel Consumption Brake Power (kW) Without Mechanical Losses Mechanical Losses ~ 0.8 kW

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Energy Balance IN OUT Calculate heat transferred to atmosphere:

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