Compute specific voume as function of pressure, temperature and composition
function v_pTX input Modelica.SIunits.AbsolutePressure p "Pressure"; input Modelica.SIunits.Temperature T "Temperature"; input Modelica.SIunits.MassFraction X[:] "Mass fractions of moist air"; output Modelica.SIunits.SpecificVolume v "Specific volume"; end v_pTX;