Compute isentropic enthalpy from upstream conditions and downstream pressure
function his_pTX_p2 input Modelica.SIunits.AbsolutePressure p "Pressure"; input Modelica.SIunits.Temperature T "Temperature"; input Modelica.SIunits.MassFraction[:] X "Mass fraction"; input Modelica.SIunits.AbsolutePressure p2 "Pressure"; output Modelica.SIunits.SpecificEnthalpy his "Specific enthalpy"; end his_pTX_p2;