Relative humidity
function phi_pTX extends Modelica.Icons.Function; input Modelica.SIunits.AbsolutePressure p "Pressure"; input Modelica.SIunits.Temperature T "Temperature"; input Modelica.SIunits.MassFraction X[:] = Modelica.Media.Air.ReferenceMoistAir.reference_X "Mass fractions"; output Real phi "Relative humidity"; end phi_pTX;