ABSTRACT
This chapter extends the idea of reversible processes to reversible and irreversible cycles, by first introducing the rather obtuse concepts associated with entropy and entropy change that takes place with irreversible processes. It deals with the concept of entropy and its use in being able to find the end-state of an irreversible process. The important cycles covered are the thermodynamically reversible Carnot cycle, the constant volume or Otto cycle, the diesel cycle and the closed constant pressure cycle. The Otto cycle is the ideal air standard cycle for the spark ignition piston engine. In this cycle it is assumed that the working fluid, air, behaves as a perfect gas and that there is no change in the composition of the air during the complete cycle. A gas turbine/compressor unit working on the ideal constant pressure cycle has air drawn into the compressor at 1 bar and 288 K which is compressed to 5 bar.
