Buildings.Utilities.Psychrometrics.Functions.BaseClasses

Information

Extends from Modelica.Fluid.Icons.BaseClassLibrary (Icon for library).

Package Content

Name	Description
Examples	Collection of models that illustrate model use and test models
der_pW_X	Derivative of function pW_X
der_pW_TDewPoi	Derivative of function pW_TDewPoi
der_pW_TDewPoi_amb	Derivative of function pW_TDewPoi_amb
der_TDewPoi_pW_amb	Derivative of function TDewPoi_pW_amb
pW_TDewPoi_amb	Partial function to compute the water vapor partial pressure for a given dew point temperature of moist air and its inverse

Buildings.Utilities.Psychrometrics.Functions.BaseClasses.der_pW_X

Information

Derivative of function Buildings.Utilities.Psychrometrics.Functions.pW_X.

Inputs

Type	Name	Default	Description
MassFraction	X_w		Species concentration at dry bulb temperature [1]
Pressure	p	101325	Total pressure [Pa]
Real	dX_w		Differential of species concentration at dry bulb temperature
Real	dp		Differential of total pressure

Outputs

Type	Name	Description
Real	dp_w	Differential of water vapor pressure

Modelica definition

function der_pW_X "Derivative of function pW_X"

  input Modelica.SIunits.MassFraction X_w(
    min=0,
    max=1,
    nominal=0.01) "Species concentration at dry bulb temperature";
  input Modelica.SIunits.Pressure p=101325 "Total pressure";

  input Real dX_w 
    "Differential of species concentration at dry bulb temperature";
  input Real dp "Differential of total pressure";

  output Real dp_w "Differential of water vapor pressure";

protected 
  Modelica.SIunits.MassFraction x_w(nominal=0.01) 
    "Water mass fraction per mass of dry air";
  Real dX_w_dX "Differential d (x_w) / d X_w";
algorithm 
  x_w := X_w/(1 - X_w);
  dX_w_dX := 1/(1-X_w)^2;
  dp_w := p * 0.62198 / (0.62198 + x_w)^2 * dX_w_dX * dX_w + x_w/(0.62198 + x_w) * dp;

end der_pW_X;

Buildings.Utilities.Psychrometrics.Functions.BaseClasses.der_pW_TDewPoi

Information

Derivative of dew point temperature calculation for moist air above freezing temperature.

Inputs

Type	Name	Default	Description
Temperature	T		Dew point temperature [K]
Real	dT		Temperature differential

Outputs

Type	Name	Description
Real	dp_w	Differential of water vapor partial pressure

Modelica definition

function der_pW_TDewPoi "Derivative of function pW_TDewPoi"

  input Modelica.SIunits.Temperature T "Dew point temperature";
  input Real dT "Temperature differential";
  output Real dp_w "Differential of water vapor partial pressure";
protected 
  constant Real C8=-5.800226E3;
  constant Real C9=1.3914993E0;
  constant Real C10=-4.8640239E-2;
  constant Real C11=4.1764768E-5;
  constant Real C12=-1.4452093E-8;
  constant Real C13=6.5459673E0;
algorithm 
  dp_w := Modelica.Math.exp(C8/T + C9 + T*(C10 + T*(C11 + T*C12)) + C13*
    Modelica.Math.log(T))*(-C8/T/T + C10 + 2*C11*T + 3*C12*T*T + C13/T)*dT;
end der_pW_TDewPoi;

Buildings.Utilities.Psychrometrics.Functions.BaseClasses.der_pW_TDewPoi_amb

Information

Derivative of dew point temperature calculation for moist air.

Extends from Buildings.Utilities.Psychrometrics.Functions.BaseClasses.pW_TDewPoi_amb (Partial function to compute the water vapor partial pressure for a given dew point temperature of moist air and its inverse).

Inputs

Type	Name	Default	Description
Temperature	T		Dew point temperature [K]
Real	dT

Outputs

Type	Name	Description
Real	dp_w	Differential of water vapor partial pressure

Modelica definition

function der_pW_TDewPoi_amb "Derivative of function pW_TDewPoi_amb"
  extends Buildings.Utilities.Psychrometrics.Functions.BaseClasses.pW_TDewPoi_amb;
  input Modelica.SIunits.Temperature T "Dew point temperature";
  input Real dT;
  output Real dp_w "Differential of water vapor partial pressure";
algorithm 
  dp_w:=a2*Modelica.Math.exp(a1 + a2*T)*dT;

end der_pW_TDewPoi_amb;

Buildings.Utilities.Psychrometrics.Functions.BaseClasses.der_TDewPoi_pW_amb

Information

Derivative of dew point temperature calculation for moist air.

Extends from Buildings.Utilities.Psychrometrics.Functions.BaseClasses.pW_TDewPoi_amb (Partial function to compute the water vapor partial pressure for a given dew point temperature of moist air and its inverse).

Inputs

Type	Name	Default	Description
Pressure	p_w		Water vapor partial pressure [Pa]
Real	dp_w		Differential of water vapor partial pressure

Outputs

Type	Name	Description
Real	dT	Differential of dew point temperature

Modelica definition

function der_TDewPoi_pW_amb "Derivative of function TDewPoi_pW_amb"
  extends Buildings.Utilities.Psychrometrics.Functions.BaseClasses.pW_TDewPoi_amb;

  input Modelica.SIunits.Pressure p_w "Water vapor partial pressure";
  input Real dp_w "Differential of water vapor partial pressure";
  output Real dT "Differential of dew point temperature";
algorithm 
  dT := dp_w / a2 / p_w;

end der_TDewPoi_pW_amb;

Buildings.Utilities.Psychrometrics.Functions.BaseClasses.pW_TDewPoi_amb

Information

Partial function to compute the dew point temperature for moist air between 0 degC and 30 degC, and for its inverse function.

Modelica definition

partial function pW_TDewPoi_amb 
  "Partial function to compute the water vapor partial pressure for a given dew point temperature of moist air and its inverse"

protected 
  constant Modelica.SIunits.Temperature T1=283.15 "First support point";
  constant Modelica.SIunits.Temperature T2=293.15 "Second support point";
  constant Modelica.SIunits.Pressure p1=1227.97 "First support point";
  constant Modelica.SIunits.Pressure p2=2338.76 "Second support point";

  constant Real a1=(Modelica.Math.log(p2) - Modelica.Math.log(p1)*T2/T1)/(1 -
      T2/T1);
  constant Real a2(unit="1/K")=(Modelica.Math.log(p1) - a1)/T1;

end pW_TDewPoi_amb;