S2. Assumptions 1 This is a steady-flow process since there is no change with time. 2 Air is an ideal gas with variable specific heats. 3 Potential energy changes are negligible. 4 There are no work interactions. Properties The gas constant of air is 0.287 kPa.m/kg.K (Table A-1). The enthalpies are (Table A-17) T=27C 300 K h = 300.19 kJ/kg T 42C 315 K h = 315.27 kJ/kg