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Buildings.HeatTransfer.Radiosity

Package with models for radiosity transfer

Information

This package provides component models for the infrared radiative heat exchange of window assemblies. The models are according to TARCOG 2006, except for the outdoor radiosity, which is computed by Buildings.HeatTransfer.Radiosity.OutdoorRadiosity. The outdoor radiosity is different from the TARCOG implementation so that the same equations are used for windows as are used for opaque walls in the room heat transfer model of the package Buildings.Rooms.

References

TARCOG 2006: Carli, Inc., TARCOG: Mathematical models for calculation of thermal performance of glazing systems with our without shading devices, Technical Report, Oct. 17, 2006.

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

Package Content

NameDescription
Buildings.HeatTransfer.Radiosity.Constant Constant Generate constant radiosity signal
Buildings.HeatTransfer.Radiosity.OpaqueSurface OpaqueSurface Model for an opaque surface
Buildings.HeatTransfer.Radiosity.IndoorRadiosity IndoorRadiosity Model for indoor radiosity
Buildings.HeatTransfer.Radiosity.OutdoorRadiosity OutdoorRadiosity Model for the outdoor radiosity that strikes the window
Buildings.HeatTransfer.Radiosity.RadiositySplitter RadiositySplitter Splits the incoming radiosity into two flows based on an input signal
Buildings.HeatTransfer.Radiosity.Examples Examples Collection of models that illustrate model use and test models
Buildings.HeatTransfer.Radiosity.BaseClasses BaseClasses Package with base classes for Buildings.HeatTransfer.Radiosity


Buildings.HeatTransfer.Radiosity.Constant Buildings.HeatTransfer.Radiosity.Constant

Generate constant radiosity signal

Buildings.HeatTransfer.Radiosity.Constant

Information

Constant radiosity source. This model requires k ≤ 0 because the radiosity leaves the component and hence needs to be negative or zero.

This model is used in Buildings.HeatTransfer.BaseClasses.DummyConstructionExterior.

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

Parameters

TypeNameDefaultDescription
Realk Radiosity that leaves this component (k <= 0)

Connectors

TypeNameDescription
output RadiosityOutflowJOut[W]

Modelica definition

block Constant "Generate constant radiosity signal"
  parameter Real k(max=0, start=0) 
    "Radiosity that leaves this component (k <= 0)";
  extends Modelica.Blocks.Interfaces.BlockIcon;

  Interfaces.RadiosityOutflow JOut;
equation 
  JOut = k;
end Constant;

Buildings.HeatTransfer.Radiosity.OpaqueSurface Buildings.HeatTransfer.Radiosity.OpaqueSurface

Model for an opaque surface

Buildings.HeatTransfer.Radiosity.OpaqueSurface

Information

Model for the emissive power of an opaque surface.

Extends from Buildings.HeatTransfer.Radiosity.BaseClasses.RadiosityOneSurface (Model for the radiosity balance of a device with one surface), Buildings.HeatTransfer.Radiosity.BaseClasses.ParametersOneSurface (Parameters that are used to model one surface).

Parameters

TypeNameDefaultDescription
AreaA Surface area [m2]
EmissivityabsIR Infrared absorptivity [1]
ReflectionCoefficientrhoIR1 - absIRInfrared reflectivity [1]
TransmissionCoefficienttauIR1 - rhoIR - absIRInfrared transmissivity [1]
BooleanlinearizefalseSet to true to linearize emissive power
TemperatureT0293.15Temperature used to linearize radiative heat transfer [K]

Connectors

TypeNameDescription
input RadiosityInflowJInIncoming radiosity [W]
output RadiosityOutflowJOutOutgoing radiosity [W]
HeatPort_aheatPortHeat port of this surface

Modelica definition

model OpaqueSurface "Model for an opaque surface"
  extends Buildings.HeatTransfer.Radiosity.BaseClasses.RadiosityOneSurface;
  extends Buildings.HeatTransfer.Radiosity.BaseClasses.ParametersOneSurface(
      final tauIR=1 - rhoIR - absIR, final rhoIR=1 - absIR);

  Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a heatPort 
    "Heat port of this surface";
protected 
  final parameter Real T03(
    min=0,
    unit="K3") = T0^3 "3rd power of temperature T0";
  final parameter Real T04(
    min=0,
    unit="K4") = T0^4 "4th power of temperature T0";
  Real T4(
    min=1E8,
    start=293.15^4,
    nominal=1E10,
    unit="K4") "4th power of temperature";

equation 
  T4 = if linearize then 4*T03*heatPort.T - 3*T04 else heatPort.T^4;
  0 = JOut + A*absIR*Modelica.Constants.sigma*T4 + rhoIR*JIn;
  0 = heatPort.Q_flow + JIn + JOut;

end OpaqueSurface;

Buildings.HeatTransfer.Radiosity.IndoorRadiosity Buildings.HeatTransfer.Radiosity.IndoorRadiosity

Model for indoor radiosity

Buildings.HeatTransfer.Radiosity.IndoorRadiosity

Information

Model for the indoor emissive power that hits a window. The computation is according to TARCOG 2006.

References

TARCOG 2006: Carli, Inc., TARCOG: Mathematical models for calculation of thermal performance of glazing systems with our without shading devices, Technical Report, Oct. 17, 2006.

Extends from Buildings.HeatTransfer.Radiosity.BaseClasses.RadiosityOneSurface (Model for the radiosity balance of a device with one surface), Buildings.HeatTransfer.Radiosity.BaseClasses.ParametersOneSurface (Parameters that are used to model one surface).

Parameters

TypeNameDefaultDescription
AreaA Surface area [m2]
EmissivityabsIR1Infrared absorptivity [1]
ReflectionCoefficientrhoIR0Infrared reflectivity [1]
TransmissionCoefficienttauIR0Infrared transmissivity [1]
BooleanlinearizefalseSet to true to linearize emissive power
TemperatureT0293.15Temperature used to linearize radiative heat transfer [K]

Connectors

TypeNameDescription
input RadiosityInflowJInIncoming radiosity [W]
output RadiosityOutflowJOutOutgoing radiosity [W]
HeatPort_aheatPortHeat port of this surface

Modelica definition

model IndoorRadiosity "Model for indoor radiosity"
  extends Buildings.HeatTransfer.Radiosity.BaseClasses.RadiosityOneSurface;
  extends Buildings.HeatTransfer.Radiosity.BaseClasses.ParametersOneSurface(
    final absIR=1,
    final tauIR=0,
    final rhoIR=0);
  Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a heatPort 
    "Heat port of this surface";
protected 
  final parameter Real T03(
    min=0,
    unit="K3") = T0^3 "3rd power of temperature T0";
  final parameter Real T04(
    min=0,
    unit="K4") = T0^4 "4th power of temperature T0";
  Real T4(
    min=1E8,
    start=293.15^4,
    nominal=1E10,
    unit="K4") "4th power of temperature";
equation 
  T4 = if linearize then 4*T03*heatPort.T - 3*T04 else heatPort.T^4;
  JOut = -A*Modelica.Constants.sigma*T4;
  0 = heatPort.Q_flow + JIn + JOut;
end IndoorRadiosity;

Buildings.HeatTransfer.Radiosity.OutdoorRadiosity Buildings.HeatTransfer.Radiosity.OutdoorRadiosity

Model for the outdoor radiosity that strikes the window

Buildings.HeatTransfer.Radiosity.OutdoorRadiosity

Information

Model for the infrared radiosity balance of the outdoor environment.

Parameters

TypeNameDefaultDescription
AreaA Area of receiving surface [m2]
RealvieFacSky View factor from receiving surface to sky (=1 for roofs)
BooleanlinearizefalseSet to true to linearize emissive power
TemperatureT0293.15Temperature used to linearize radiative heat transfer [K]

Connectors

TypeNameDescription
input RealInputTOutOutside temperature [K]
input RealInputTBlaSkyBlack body sky temperature [K]
output RadiosityOutflowJOutRadiosity that flows out of component [W]

Modelica definition

model OutdoorRadiosity 
  "Model for the outdoor radiosity that strikes the window"
  parameter Modelica.SIunits.Area A "Area of receiving surface";
  parameter Real vieFacSky(min=0, max=1) 
    "View factor from receiving surface to sky (=1 for roofs)";
  parameter Boolean linearize=false "Set to true to linearize emissive power";
  parameter Modelica.SIunits.Temperature T0=293.15 
    "Temperature used to linearize radiative heat transfer";
  Real TRad4(unit="K4") "4th power of the mean outdoor temperature";
  Modelica.SIunits.Temperature TRad "Mean radiant temperature";

  Modelica.Blocks.Interfaces.RealInput TOut(
    final quantity="ThermodynamicTemperature",
    final unit="K",
    min=0) "Outside temperature";
  Modelica.Blocks.Interfaces.RealInput TBlaSky(
    final quantity="ThermodynamicTemperature",
    final unit="K",
    min=0) "Black body sky temperature";
  Buildings.HeatTransfer.Interfaces.RadiosityOutflow JOut 
    "Radiosity that flows out of component";
protected 
  final parameter Real T03(
    min=0,
    unit="K3") = T0^3 "3rd power of temperature T0";
  final parameter Real T04(
    min=0,
    unit="K4") = T0^4 "4th power of temperature T0";
equation 
  TRad4 = (vieFacSky*TBlaSky^4 + (1 - vieFacSky)*TOut^4);
  JOut = -A*Modelica.Constants.sigma*TRad4;
  TRad = if linearize then (TRad4 + 3*T04)/(4*T03) else TRad4^(1/4);

end OutdoorRadiosity;

Buildings.HeatTransfer.Radiosity.RadiositySplitter Buildings.HeatTransfer.Radiosity.RadiositySplitter

Splits the incoming radiosity into two flows based on an input signal

Buildings.HeatTransfer.Radiosity.RadiositySplitter

Information


This blocks splits the incoming radiosity into two fluxes according to

JOut,1 = - u JIn,
JOut,2 = - (1-u) JIn.

The minus sign on the left hand side is because JIn and JOut are flow variables.

This block may be used to split the radiosity flux into a fraction that strikes the shaded part of a window, and a fraction that strikes the non-shaded part.

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

Connectors

TypeNameDescription
input RadiosityInflowJIn[W]
input RealInputuu times incoming radiosity
output RadiosityOutflowJOut_1[W]
output RadiosityOutflowJOut_2(1-u) times incoming radiosity [W]

Modelica definition

block RadiositySplitter 
  "Splits the incoming radiosity into two flows based on an input signal"
  extends Modelica.Blocks.Interfaces.BlockIcon;

  Interfaces.RadiosityInflow JIn;
  Modelica.Blocks.Interfaces.RealInput u(min=0, max=1) 
    "u times incoming radiosity";
  Interfaces.RadiosityOutflow JOut_1;

  Interfaces.RadiosityOutflow JOut_2 "(1-u) times incoming radiosity";
equation 
  JOut_1 = - u    * JIn;
  JOut_2 = - (1-u)* JIn;
end RadiositySplitter;

Automatically generated Wed Feb 29 16:53:50 2012.