For a temperature range of 0 to 100°F( 17.8to37.8°C),cpd can be taken as 0.240Btu/lb °F (1005J/kg K)and cps as0.444Btu/lb °F(1859J/kg K).Most of the calculations of cpa(T2T1)
have a range of w between 0.005 and 0.010lb/lb(kg/kg).Taking a mean value of w 0.0075 lb/lb (kg/kg), we find that