Buildings.BoundaryConditions.SkyTemperature

Information

Extends from Modelica.Icons.VariantsPackage (Icon for package containing variants).

Package Content

Name	Description
BlackBody	Calculate black body sky temperature
Examples	Collection of models that illustrate model use and test models

Buildings.BoundaryConditions.SkyTemperature.BlackBody

Information

This component computes the black-body sky temperature.

For calTSky = 0, the model uses horizontal infrared irradiation. Otherwise, it uses dry buld temperature, dew point temperature and opaque sky cover.

Extends from Modelica.Blocks.Interfaces.BlockIcon (Basic graphical layout of input/output block).

Parameters

Type	Name	Default	Description
Integer	calTSky		0: Use radHor; 1: Use TDry, TDewPoi and nOpa

Connectors

Type	Name	Description
input RealInput	TDryBul	Dry bulb temperature at ground level [K]
input RealInput	TDewPoi	Dew point temperature [K]
input RealInput	nOpa	Opaque sky cover
output RealOutput	TBlaSky	Black-body sky temperature [K]
input RealInput	radHor	Horizontal infrared irradiation [W/m2]

Modelica definition

block BlackBody "Calculate black body sky temperature"
  extends Modelica.Blocks.Interfaces.BlockIcon;
  parameter Integer calTSky(min=0, max=1) 
    "0: Use radHor; 1: Use TDry, TDewPoi and nOpa";
  Modelica.Blocks.Interfaces.RealInput TDryBul(
    final quantity="Temperature",
    final unit="K",
    displayUnit="degC") "Dry bulb temperature at ground level";
  Modelica.Blocks.Interfaces.RealInput TDewPoi(
    final quantity="Temperature",
    final unit="K",
    displayUnit="degC") "Dew point temperature";
  Modelica.Blocks.Interfaces.RealInput nOpa "Opaque sky cover";
  Modelica.Blocks.Interfaces.RealOutput TBlaSky(
    final quantity="Temperature",
    displayUnit="degC",
    final unit="K") "Black-body sky temperature";
  Modelica.Blocks.Interfaces.RealInput radHor(unit="W/m2", min=0, nominal=100) 
    "Horizontal infrared irradiation";
protected 
  Modelica.SIunits.Temperature TDewPoiK "Dewpoint temperature";
  Modelica.SIunits.Emissivity epsSky "Black-body absorptivity of sky";
  Real nOpa10(min=0, max=10) "Opaque sky cover";
algorithm 
  if calTSky == 1 then
    TBlaSky := (radHor/Modelica.Constants.sigma)^0.25;
  else
    TDewPoiK := Buildings.Utilities.Math.Functions.smoothMin(TDryBul, TDewPoi, 0.1);
    nOpa10 := 10*nOpa "Input nOpa is scaled to [0,1] instead of [0,10]";
    epsSky := (0.787 + 0.764*Modelica.Math.log(-TDewPoiK/Modelica.Constants.T_zero))*(1 + 0.0224*nOpa10 -
      0.0035*(nOpa10^2) + 0.00028*(nOpa10^3));
    TBlaSky := TDryBul*(epsSky^0.25);
  end if;
end BlackBody;