This function computes the number of phases for R134a depending on
the inputs for absolute pressure and specific entropy. It makes use
of cubic spline functions for liquid and vapor specific entropy.
function getPhase_ps
extends Modelica.Icons.Function;
input AbsolutePressure p "Pressure";
input SpecificEntropy s "Specific entropy";
output Integer phase "Number of phases";
end getPhase_ps;