-: Actual Cycle :-
If we subtract losses due to variable specific heat and dissociation from air standard cycle then we get fuel air cycle and if we further subtract other losses from fuel air cycle then the obtained cycle is know as Actual Cycle .
-: Losses of Actual Cycle :-
An actual cycle efficiency is much lower than the air stand and efficiency due to various losses occurring in the actual engine. These losses are as follows-
1- Losses due to variation of specific heats with temperature .
2- Losses due to Dissociation .
3- Time Losses :- In Actual Cycle, burning is completed in a definite interval of time. The effect of this time is that the maximum pressure will not be produced when the volume is minimum, but sometime after T.D.C, causes a reduction in the work produced. The time at which burning starts is varied by varying the spark timing .
4-Incomplete Combustion lass :- Fuel vapour,air,and residual gas are present in the cylinder this makes it impossible to obtained perfect homogeneous mixture. Therefore some fuel does't burn to CO2 or partially burns to CO and O2 will appear in the exhaust. Energy release in actual engine is about 90 to 93%of fuel energy in put.
5- Direct heat loss:- During combustion process and subsequent expansion stroke , the heat flows from cylinder Gases through cylinder walls and cylinder head into the water jacket or cooling fins. Some heat enters the piston head and flows of the cylinder or carried away by the engine oil.
The heat loss during combustion and expansion does not represent a complete heat loss., a part of the heat loss would be rejected in the exhaust at the and of the expansion stroke .
6- Exhaust blow-down loss :- The opening of the exhaust value before BDC reducing cylinder pressure, causing the roundness of the end of the P-V diagram, this means a reduction in the work done per cycle.
7- Pumping Losses :-
Pumping loss is due to expelling the exhaust gases and the induction of the fresh charge . In naturally as pirated engine . This would be a negative work .
8- Friction Losses :-
These losses are due to the friction between the piston and cylinder walls .
If we subtract losses due to variable specific heat and dissociation from air standard cycle then we get fuel air cycle and if we further subtract other losses from fuel air cycle then the obtained cycle is know as Actual Cycle .
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-: Losses of Actual Cycle :-
An actual cycle efficiency is much lower than the air stand and efficiency due to various losses occurring in the actual engine. These losses are as follows-
1- Losses due to variation of specific heats with temperature .
2- Losses due to Dissociation .
3- Time Losses :- In Actual Cycle, burning is completed in a definite interval of time. The effect of this time is that the maximum pressure will not be produced when the volume is minimum, but sometime after T.D.C, causes a reduction in the work produced. The time at which burning starts is varied by varying the spark timing .
4-Incomplete Combustion lass :- Fuel vapour,air,and residual gas are present in the cylinder this makes it impossible to obtained perfect homogeneous mixture. Therefore some fuel does't burn to CO2 or partially burns to CO and O2 will appear in the exhaust. Energy release in actual engine is about 90 to 93%of fuel energy in put.
5- Direct heat loss:- During combustion process and subsequent expansion stroke , the heat flows from cylinder Gases through cylinder walls and cylinder head into the water jacket or cooling fins. Some heat enters the piston head and flows of the cylinder or carried away by the engine oil.
The heat loss during combustion and expansion does not represent a complete heat loss., a part of the heat loss would be rejected in the exhaust at the and of the expansion stroke .
6- Exhaust blow-down loss :- The opening of the exhaust value before BDC reducing cylinder pressure, causing the roundness of the end of the P-V diagram, this means a reduction in the work done per cycle.
7- Pumping Losses :-
Pumping loss is due to expelling the exhaust gases and the induction of the fresh charge . In naturally as pirated engine . This would be a negative work .
8- Friction Losses :-
These losses are due to the friction between the piston and cylinder walls .
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