Friday, August 26, 2011

Assumptions in Thermodynamic Cycles

                    The analysis of all thermodynamics cycles is based on the following assumptions:

1. The gas in the engine cylinder is a perfect gas, i.e. it obeys the gas laws and constant specific heats.
2. The physical constants of the gas in the engine cylinder are same as those of air at moderate temperature.
3. All the compression and expansion processes are adiabatic and they take place without any internal friction.
4. Heat is supplied by bringing a hot body in contact with the cylinder at appropriate points during the process. Similarly heat is rejected by bringing a cold body in contact with the cylinder at these points.
5. The cycle is considered to be a closed one and the same air is used again and again to repeat the cycle.
6. No chemical reaction, whatsoever, takes place in the engine cylinder.