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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

Name Description
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.Icons.Block (Basic graphical layout of input/output block).


Parameters




TypeNameDefaultDescription


SkyTemperatureCalculationcalTSkySkyTemperatureCalculation.Te...Computation of black-body sky temperature




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 RealInputradHorIRHorizontal infrared irradiation [W/m2]




Modelica definition


block BlackBody "Calculate black body sky temperature"
  extends Modelica.Blocks.Icons.Block;
  import Buildings.BoundaryConditions.Types.SkyTemperatureCalculation;
  parameter Buildings.BoundaryConditions.Types.SkyTemperatureCalculation calTSky=
    SkyTemperatureCalculation.TemperaturesAndSkyCover 
    "Computation of black-body sky temperature";
  Modelica.Blocks.Interfaces.RealInput TDryBul(
    final quantity="ThermodynamicTemperature",
    final unit="K",
    displayUnit="degC") "Dry bulb temperature at ground level";
  Modelica.Blocks.Interfaces.RealInput TDewPoi(
    final quantity="ThermodynamicTemperature",
    final unit="K",
    displayUnit="degC") "Dew point temperature";
  Modelica.Blocks.Interfaces.RealInput nOpa "Opaque sky cover";
  Modelica.Blocks.Interfaces.RealOutput TBlaSky(
    final quantity="ThermodynamicTemperature",
    displayUnit="degC",
    final unit="K") "Black-body sky temperature";
  Modelica.Blocks.Interfaces.RealInput radHorIR(
    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 == Buildings.BoundaryConditions.Types.SkyTemperatureCalculation.TemperaturesAndSkyCover then
    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);
  else
    TDewPoiK := 273.15;
    nOpa10   := 0.0;
    epsSky   := 0.0;
    TBlaSky  := (radHorIR/Modelica.Constants.sigma)^0.25;
  end if;
end BlackBody;






Automatically generated Thu Jun 19 10:54:24 2014.