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
SkyTemperatureCalculation	calTSky	SkyTemperatureCalculation.Te...	Computation of black-body sky temperature

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	radHorIR	Horizontal infrared irradiation [W/m2]

Modelica definition

block BlackBody "Calculate black body sky temperature"
  extends Modelica.Blocks.Interfaces.BlockIcon;
  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="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 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;