I.C. ENGINES

1. I.C. ENGINES Practical No: 7 (5 May, 2014)

2. Fuel Consumption • Objective • To calculate thermal efficiency of the engine • Apparatus • Engine test bench • Accurate measuring tank • Flow meter • Stop watch (min time should be not less than two minutes)

3. Fuel Consumption • Procedure • Use test tank with hook gauges • Or calibrated glass measuring cylinder • Measuring glass shaped so that fuel falls fast at the points of calibration where time finished and finishes • An other method is to use flow meter

4. Fuel Consumption • Procedure • The scale are not linear since the quantity of fuel flowing in unit time

5. Fuel Consumption • Calculation • To convert milliliter (ml) or liters ( l) to mass ( kg) • 1000 ml = 1 litre • Since 1 litre of water has a mass of 1 kg • 1 litre of fuel has a mass of 1 x relative density of fuel (kg) • X litre of fuel has a mass of : • X x relative density of fuel ( kg)

6. Fuel Consumption • Calculation • The quantity of fuel consumed is measured in litre per brake power ( kW) per hour , or kg per brake power ( kW) per hour

7. Fuel Consumption • Calculation

8. Example • A Morse test on an engine gave the following results: • Pb All cylinder working 100 kW • Pb No 1 cylinder cut out 69 kW • Pb No 1 cylinder cut out 71 kW • Pb No 1 cylinder cut out 68.5 kW • Pb No 1 cylinder cut out 71.5 kW • Find Pi , Pf and Mechanical efficiency

9. Example • Formula • Pi = (A x 4) - (B1 +B2+B3+ B4) • Sol • Pi = (100 x4) – ( 69+ 71 + 68.5 + 71.5) • = 400 – 280 • Pi = 120 kW • Pf = Pi - Pb • = 120 – 100 • Pf = 20 kW

10. Example • Sol • MechEff = 83 %