# 0.2 m3 of air at 4 bar and 130°C is contained in.. solved problem

#### 0.2 m3 of air at 4 bar and 130°C is contained in a system. A reversible adiabatic expansion lakes place till the pressure falls to 1.02 bar. The gas is then heated at constant pressure till enthalpy increases by 72.5 kJ. Calculate : (i) The work done ; (ii) The index of expansion, if the above processes are replaced by a single reversible polytropic process giving the same work between the same initial and final states. Take cp = 1 kJ/kg K, cv = 0.714 kJ/kg K.

0.2 m3 of air at 4 bar and 130°C is contained in a system. A reversible adiabatic expansion lakes place till the pressure falls to 1.02 bar. The gas is then heated at constant pressure till enthalpy increases by 72.5 kJ. Calculate :
(i) The work done ;
(ii) The index of expansion, if the above processes are replaced by a single reversible polytropic process giving the same work between the same initial and final states.
Take cp = 1 kJ/kg K, cv = 0.714 kJ/kg K.