0.6 $m^3$ of air at $37^oC$ and 1 bar is heated at constant volume until the pressure becomes 2 bar. It is then cooled at constant pressure to its original temperature.

Given: $V_1= 0.6m^3, T_1= 310K, P_1 = 1 bar$

1. Constant Volume Heating to $P_2 = 2 bar, T_2 = 620K$
2. Constant Pressure Cooling to 310K

Solution:

For Constant Volume Process

$ΔS = C_vlog_e(\frac{T_3}{T_2})$

$ΔS = 0.718 × log_e (\frac{620}{310})$

$ΔS = 0.49767 kJ/kg$

For Constant Pressure Process

$ΔS = C_plog_e(\frac{T_3}{T_2})$

$ΔS = 1.005 × log_e (\frac{310}{620})$

$ΔS = -0.6966 kJ/kg$