Buildings.BoundaryConditions.SkyTemperature

Package with models to compute the sky temperature

Information


This package contains models to compute the black body sky temperature.

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

Package Content

NameDescription
Buildings.BoundaryConditions.SkyTemperature.BlackBody BlackBody Calculate black body sky temperature
Buildings.BoundaryConditions.SkyTemperature.Examples Examples Collection of models that illustrate model use and test models


Buildings.BoundaryConditions.SkyTemperature.BlackBody Buildings.BoundaryConditions.SkyTemperature.BlackBody

Calculate black body sky temperature

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

TypeNameDefaultDescription
IntegercalTSky 0: Use radHor; 1: Use TDry, TDewPoi and nOpa

Connectors

TypeNameDescription
input RealInputTDryBulDry bulb temperature at ground level [K]
input RealInputTDewPoiDew point temperature [K]
input RealInputnOpaOpaque sky cover
output RealOutputTBlaSkyBlack-body sky temperature [K]
input RealInputradHorHorizontal 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;

Automatically generated Fri May 06 14:10:58 2011.