Enthalpy of vaporization of water is computed from temperature.
As the enthalpy is a state function, it does not depend on the transformation path. Therefore, the enthalpy of vaporisation at a given temperature is computed from the enthalpy of vaporisation at 2°C corrected by the sensible enthalpy diffence between the temperature T and 0°C
function enthalpyOfVaporization extends Modelica.Icons.Function; input Temperature T "Temperature"; output SpecificEnthalpy r0 "Vaporization enthalpy"; end enthalpyOfVaporization;