Derivative of specific inner energy wrt. specific enthalpy at constant pressure in vapor region for given pressure and specific enthalpy
function du2hp_Ph input Units.SI.AbsolutePressure p "Pressure"; input Units.SI.SpecificEnthalpy h "Specific enthalpy"; output Real duhp(unit = "1") "Derivative of specific inner energy wrt. specific enthalpy at constant pressure"; end du2hp_Ph;