function [vg]=vg(T) 
  %gas specific volume [m^3/kg] at T [celsius] 
 
 Tsat=[0:10:370,374.15];
  %saturation temperature in celsius

 vvap=[206.146,106.422,57.836,32.929,19.546,12.045,7.6776,5.0453,3.4083,2.3609,1.6730,1.2101,0.89171,0.66832,.50866,.39257,.30685,.24262,.19385,.15635,.12719,.104265,.086062,.071472,.059674,.05056,.042149,.035599,.030133,.025537,.021643,.018316,.015451,.012967,.010779,.008805,.006943,.00493,.00317];%
  %saturated vapor specific volume in m^3/kg

vg=interp1(Tsat,vvap,T);