Buildings.Utilities.Psychrometrics.Functions.Examples

Information

This package contains examples for the use of models that can be found in Buildings.Utilities.Psychrometrics.Functions.

Package Content

Name	Description
pW_X	Model to test pW_X and its inverse function
pW_TDewPoi	Model to test pW_TDewPoi and its inverse function
pW_TDewPoi_comparison	Model to test the approximation for pW_TDewPoi and its inverse function
X_pSatpphi	Model to test X_pSatpphi function

Buildings.Utilities.Psychrometrics.Functions.Examples.pW_X

Information

Modelica definition

model pW_X "Model to test pW_X and its inverse function"
  extends Modelica.Icons.Example;

  Modelica.SIunits.MassFraction X "Mass fraction";
  Modelica.SIunits.MassFraction XInv "Mass fraction";
  Modelica.SIunits.MassFraction dX "Difference between mass fraction";
  Modelica.SIunits.Pressure p_w "Water vapor partial pressure";
  constant Real conv(unit="1/s") = 0.999 "Conversion factor";
equation 
  X = conv*time;
  p_w = Buildings.Utilities.Psychrometrics.Functions.pW_X(X);
  XInv = Buildings.Utilities.Psychrometrics.Functions.X_pW(p_w);
  dX = X - XInv;
  assert(abs(dX) < 10E-12, "Error in function implementation.");
end pW_X;

Buildings.Utilities.Psychrometrics.Functions.Examples.pW_TDewPoi

Information

Modelica definition

model pW_TDewPoi "Model to test pW_TDewPoi and its inverse function"
  extends Modelica.Icons.Example;

  Modelica.SIunits.Temperature T "Dew point temperature";
  Modelica.SIunits.Temperature TInv "Dew point temperature";
  Modelica.SIunits.TemperatureDifference dT "Difference between temperatures";
  Modelica.SIunits.Pressure p_w "Water vapor partial pressure";
  constant Real conv(unit="K/s") = 100 "Conversion factor";
equation 
  T = conv*time + 273.15;
  p_w = Buildings.Utilities.Psychrometrics.Functions.pW_TDewPoi(T);
  TInv = Buildings.Utilities.Psychrometrics.Functions.TDewPoi_pW(p_w);
  dT = T - TInv;
  assert(abs(dT) < 10E-12, "Error in function implementation.");
end pW_TDewPoi;

Buildings.Utilities.Psychrometrics.Functions.Examples.pW_TDewPoi_comparison

Information

Modelica definition

model pW_TDewPoi_comparison 
  "Model to test the approximation for pW_TDewPoi and its inverse function"
  extends Modelica.Icons.Example;

  Modelica.SIunits.Temperature T "Dew point temperature";
  Modelica.SIunits.Temperature TInv "Dew point temperature";
  Modelica.SIunits.TemperatureDifference dT "Difference between temperatures";
  Modelica.SIunits.Pressure p_w_ashrae 
    "Water vapor partial pressure according to the ASHRAE handbook";
  Modelica.SIunits.Pressure p_w "Water vapor partial pressure";

  constant Real conv(unit="K/s") = 30 "Conversion factor";
  Real r_p "Ratio of the two approximations";
equation 
  T = conv*time + 273.15;
  p_w_ashrae = Buildings.Utilities.Psychrometrics.Functions.pW_TDewPoi(T);
  p_w = Buildings.Utilities.Psychrometrics.Functions.pW_TDewPoi_amb(T);
  r_p = p_w_ashrae/p_w;
  p_w = Buildings.Utilities.Psychrometrics.Functions.pW_TDewPoi_amb(TInv);
  dT = T - TInv;
  assert(abs(dT) < 10E-12, "Error in function implementation.");
end pW_TDewPoi_comparison;

Buildings.Utilities.Psychrometrics.Functions.Examples.X_pSatpphi

Information

This example computes the water content of air for a relative humidity between 0 and 100%, a temperature of 20ˆC and atmospheric pressure.

Parameters

Type	Name	Default	Description
Temperature	T	293.15	Temperature [K]
Pressure	p	101325	Pressure of the fluid [Pa]

Modelica definition

model X_pSatpphi "Model to test X_pSatpphi function"
  extends Modelica.Icons.Example;
  package Medium = Buildings.Media.PerfectGases.MoistAir "Medium model";
  parameter Modelica.SIunits.Temperature T = 293.15 "Temperature";
  Modelica.SIunits.AbsolutePressure pSat "Saturation pressure";
  parameter Modelica.SIunits.Pressure p = 101325 "Pressure of the fluid";
  Real phi(min=0, max=1) "Relative humidity";
  Modelica.SIunits.MassFraction X_w(
    min=0,
    max=1,
    nominal=0.01) "Water vapor concentration per total mass of air";

  constant Real conv(unit="1/s") = 1 "Conversion factor";
equation 
  phi = time;
  pSat = Medium.saturationPressure(T);
  X_w = Buildings.Utilities.Psychrometrics.Functions.X_pSatpphi(pSat=pSat, p=p, phi=phi);

end X_pSatpphi;