The ideal gas constant for moist air is computed from the density d, temperature T and composition X where the mass fractions of dry air and steam are corrected of the mass fraction of liquid that does not count for the gas contant calculation.
function r_dTX
input SI.Density d "Density";
input SI.Temperature T "Temperature";
input SI.MassFraction X[:] "Mass fractions of moist air";
output SI.SpecificHeatCapacity R "Mixture gas constant";
end r_dTX;