This function calculates the density and temperature of R134a from absolute pressure and specific enthalpy. In one-phase region the function calls the fundamental Helmholtz equation of Tillner-Roth (1994). In two-phase the density and temperature is computed from cubic splines for saturated pressure, liquid and vapor density.
function dt_ph extends Modelica.Icons.Function; input AbsolutePressure p "Pressure"; input SpecificEnthalpy h "Specific enthalpy"; output Density d "Density"; output Temperature T "Temperature"; end dt_ph;