Determine the net work:
Q: 5 m3 of air at 2 bar, 27°C is compressed to 6 bar pressure following PV1.3 =C. It is expanded subsequently adiabatically to 2 bar. Considering two processes is to be reversed, determine the net work. Also plot the processes on T - S diagram.
Sol: Given that:
Initial volume of air V1 = 5 m3
Initial pressure of air P1 = 2 bar
Final pressure = 6 bar
Compression: Rev. Polytropic process (PVn = C) Expansion :Rev. adiabatic process (PV14 = C) Now, work done during the process (1-2)
negative sign shows that work input required for compression is more than work output obtained during expansion.