Internal Combustion

Fundamentals

Prof. (Dr.) M P Poonia Director

NITTTR, Chandigarh

AIR STANDARD CYCLE

EFFECT OF SPECIFIC HEAT

1-2-3-4 Constant Specific Heat

1-2”-3”-4” Variable Specific Heat

P

V

EFFECT OF DISSOCIATION

P

V

Tmax

POOR UTILISATION OF HEAT

Flame front Fuel spray flame

Premixed charge (gasoline)

Non-premixed charge (Diesel)

Spark plug Fuel injector

Fuel + air mixture Air only

PREMIXED vs. NON-PREMIXED CHARGE

ENGINES

IDEAL HEAT ADDITION

THE IDEAL AİR STANDARD OTTO

CYCLE

ACTUAL HEAT ADDITION

LOSSES IN ACTUAL CYCLES

TIME LOSS

HEAT LOSS

HEAT LOSS

BLOW DOWN LOSS

BLOW DOWN LOSS

BLOW BYE LOSSES

RUBBING FRICTION LOSS

PUMPING LOSS

Blow Down Loss

Heat Transfer Loss

Combustion Loss

Pumping LossV

P

LOSSES DURING CYCLE

MAGNITUDE OF LOSSES

MAGNITUDE OF LOSSES

The actual efficiency of a good engine is about ……… of the estimated air fuel cycle efficiency.a) 100%b) 85%c) 50%d) 25

FAQ

Fuel air efficiency is less than air standard efficiency by an amount equal toa) pumping lossb) friction lossc) loss due to specific heat and chemical equilibriumd) exhaust blow down loss

FAQ

Fuel air ratio affects maximum power output of the engine due toa) higher specific heatsb) chemical equilibrium lossesc) all of the mentionedd) none of the mentioned

FAQ

As compared to air cycle, in actual working, the effect of variation in specific heats is toa) increase maximum pressure and maximum temperatureb) reduce maximum pressure and maximum temperaturec) increase maximum pressure and decrease maximum temperatured) none of the mentioned

FAQ

As compared to air cycle, in actual working, the effect of variation in specific heats is toa) increase maximum pressure and maximum temperatureb) reduce maximum pressure and maximum temperaturec) increase maximum pressure and decrease maximum temperatured) none of the mentioned

FAQ

Thanks