.Buildings.Utilities.Psychrometrics.Functions.density_pTX

Information

Function to compute the density of moist air for given pressure, temperature and water vapor mass fraction.

Note that the water vapor mass fraction is in kg/kg total air.

Interface

function density_pTX
  extends Modelica.Icons.Function;
  input Modelica.Units.SI.Pressure p "Absolute pressure of the medium";
  input Modelica.Units.SI.Temperature T "Dry bulb temperature";
  input Modelica.Units.SI.MassFraction X_w "Water vapor mass fraction per unit mass total air";
  output Modelica.Units.SI.Density d "Mass density";
end density_pTX;

Revisions

• September 19, 2025, by Michael Wetter:
  Inlined function, as this function is often used by the multizone airlfow models. This further improves the computing time.
  This is for IBPSA, #2043.
• November 23, 2015 by Filip Jorissen:
  Added derivative information for avoiding numerical Jacobians.
• February 24, 2015 by Michael Wetter:
  First implementation.