An engine uses air as the operating substance. At the beginning of compression the pressure is 90 KN /m2 and the temp. is 400C. During the adiabatic compression, the volume is reduced to one-sixteenth of its normal value at the beginning of the compression stroke. Heat is then added at constant pressure until the temp. is 14000C. The stroke is completed by adiabatic expansion until the initial volume is reached, when the cycle is closed by a constant volume process.
a) Draw the P-V and T-S diagram of the engine.
b) Determine the temperature and pressure at all the corners of the diagram.
c) Calculate the thermal efficiency of the cycle.
d) Derive the expression used.