Calculates time derivative of specificEnthalpy_ps
function specificEnthalpy_ps_der input AbsolutePressure p "Pressure"; input SpecificEntropy s "Specific entropy"; input FixedPhase phase = 0 "2 for two-phase, 1 for one-phase, 0 if not known"; input Real der_p "Time derivative of pressure"; input Real der_s "Time derivative of specific entropy"; output Real der_h "Time derivative of specific enthalpy"; end specificEnthalpy_ps_der;