Buildings.Utilities.Psychrometrics.Functions.BaseClasses

Information

This package contains base classes that are used to construct the models in Buildings.Utilities.Psychrometrics.Functions.

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.

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.

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;