function [Cpg]=Cpg(T) 
  %gas specific heat [kJ/kg*C] at T [celsius] 
 
 Tsat=[0:10:370,374.15];
  %saturation temperature in celsius

 Cpvap=[1.863,1.870,1.880,1.890,1.900,1.912,1.924,1.946,1.970,1.999,2.034,2.076,2.125,2.180,2.245,2.320,2.406,2.504,2.615,2.741,2.883,3.043,3.223,3.426,3.656,3.918,4.221,4.575,4.996,5.509,6.148,6.968,8.060,9.580,11.87,15.8,27.0,107.0,1e5];
 %vapor specific heat [kJ/kg*C] at T [celsius] 

Cpg=interp1(Tsat,Cpvap,T);