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Buildings.HeatTransfer.Windows

Package with models for windows

Information

This package contains models for heat transfer in windows.

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

Package Content

NameDescription
Buildings.HeatTransfer.Windows.Window Window Model for a window
Buildings.HeatTransfer.Windows.ExteriorHeatTransfer ExteriorHeatTransfer Model for heat convection at the exterior surface of a window that may have a shading device
Buildings.HeatTransfer.Windows.InteriorHeatTransfer InteriorHeatTransfer Model for heat convection at the interior surface of a window that may have a shading device
Buildings.HeatTransfer.Windows.Examples Examples Collection of models that illustrate model use and test models
Buildings.HeatTransfer.Windows.BaseClasses BaseClasses Package with base classes for Buildings.HeatTransfer.Windows
Buildings.HeatTransfer.Windows.Functions Functions Functions used in window radiation model


Buildings.HeatTransfer.Windows.Window Buildings.HeatTransfer.Windows.Window

Model for a window

Buildings.HeatTransfer.Windows.Window

Information

Overview

This is a model for a window system. The equations are similar to the equations used in the Window 5 model and described in TARCOG 2006. The model computes the heat balance from the exterior surface to the room-facing surface for a window system. The window system can have an exterior or an interior shade, but not both, or it can have no shade. The convective heat transfer between the window system and the outside air or the room is not computed by this model. They can be computed using the models Buildings.HeatTransfer.Windows.ExteriorHeatTransfer and Buildings.HeatTransfer.Windows.InteriorHeatTransfer.

Limitations

To calculate the angular transmittance, reflectance and absorptance of a glazing system, Window 5 model first calculates the value for each wave length, then calculate the weighted value over entire wave lengths. Current window model in Buildings library only uses the weighted value of each glass. As a result, there are some differences in prediciton between the current Modelica window model and WINDOW 5. The difference is small for single layer window or multi-layer window with the same glasses. But it can be large for multi-layer window with different glasses.

Parameters

This model takes as the parameter glaSys a data record from the package Buildings.HeatTransfer.Data.GlazingSystems. This data record specifies the properties of the glasses, the gas fills, the frame and of the shades, if any shade is present. Whether a shade is present or not is determined by the parameters glaSys.haveExteriorShade and glaSys.haveInteriorShade.

The parameter linearize can be used to linearize the model equations.

Ports

If a shade is present, then the input port u is used to determine the shade position. Set u=0 to have the window in the unshaded mode, and set u=1 to have the window shade completely deployed. Any intermediate value is possible. If no shade is present, then this port will be removed.

For the heat ports, the suffix _a is used for the exterior, outside-facing side of the window, and the suffix _b is used for the interior, room-facing surface of the window. Each side has heat ports that connect to the glass, to the frame, and, optionally, to the shade. If no shade is present, then the heat port to the shade will be removed.

Description of the Physics

The model has three main submodels that implement the relevant heat balances:

  1. The model frame computes heat conduction through the frame.
  2. The model glaUns computes the heat balance of the part of the window that is unshaded. For example, if u=0.2, then this model accounts for the 80% of the window that is not behind the shade or blind.
  3. The model glaSha computes the heat balance of the part of the window that is shaded. For example, if u=0.2, then this model accounts for the 20% of the window that is behind the shade or blind. If the parameter glaSys specifies that the window has no exterior and no interior shade, then the model glaSha will be removed.
  4. The models glaUns and glaSha compute the solar radiation that is absorbed by each glass pane and the solar radiation that is transitted through the window as a function of the solar incidence angle. They then compute a heat balance that takes into account heat conduction through the glass, heat convection through the gas layer, and infrared radiation from the exterior and the room through the glass and gas layers. The infrared radiative heat exchange is computed using a radiosity balance. Heat conduction through the frame is computed using a heat flow path that is parallel to the glazing system, i.e., there is no heat exchange between the frame and the glazing layer.

    References

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

    Parameters

    TypeNameDefaultDescription
    GenericglaSys Glazing system
    AreaA Heat transfer area [m2]
    RealfFra0.1Fraction of frame
    BooleanlinearizefalseSet to true to linearize emissive power
    Angletil Surface tilt [rad]

    Connectors

    TypeNameDescription
    output RadiosityOutflowJOutUns_aOutgoing radiosity that connects to unshaded part of glass at exterior side [W]
    input RadiosityInflowJInUns_aIncoming radiosity that connects to unshaded part of glass at exterior side [W]
    output RadiosityOutflowJOutSha_aOutgoing radiosity that connects to shaded part of glass at exterior side [W]
    input RadiosityInflowJInSha_aIncoming radiosity that connects to shaded part of glass at exterior side [W]
    output RadiosityOutflowJOutUns_bOutgoing radiosity that connects to unshaded part of glass at room-side [W]
    input RadiosityInflowJInUns_bIncoming radiosity that connects to unshaded part of glass at room-side [W]
    output RadiosityOutflowJOutSha_bOutgoing radiosity that connects to shaded part of glass at room-side [W]
    input RadiosityInflowJInSha_bIncoming radiosity that connects to shaded part of glass at room-side [W]
    HeatPort_aglaUns_aHeat port at unshaded glass of exterior-facing surface
    HeatPort_bglaUns_bHeat port at unshaded glass of room-facing surface
    HeatPort_aglaSha_aHeat port at shaded glass of exterior-facing surface
    HeatPort_bglaSha_bHeat port at shaded glass of room-facing surface
    HeatPort_afra_aHeat port at frame of exterior-facing surface
    HeatPort_bfra_bHeat port at frame of room-facing surface
    input RealInputuShaControl signal for the shading device. 0: unshaded; 1: fully shaded (removed if no shade is present)
    input RealInputQAbsUns_flow[glaSys.nLay]Solar radiation absorbed by unshaded part of glass [W]
    input RealInputQAbsSha_flow[glaSys.nLay]Solar radiation absorbed by shaded part of glass [W]

    Modelica definition

    model Window "Model for a window"
    
      parameter Buildings.HeatTransfer.Data.GlazingSystems.Generic glaSys 
        "Glazing system";
      parameter Modelica.SIunits.Area A "Heat transfer area";
      parameter Real fFra(min=0, max=1)=0.1 "Fraction of frame";
      final parameter Modelica.SIunits.Area AFra = fFra*A "Frame area";
      final parameter Modelica.SIunits.Area AGla = A-AFra "Glass area";
      parameter Boolean linearize=false "Set to true to linearize emissive power";
      parameter Modelica.SIunits.Angle til(displayUnit="deg") "Surface tilt";
    
      Interfaces.RadiosityOutflow JOutUns_a 
        "Outgoing radiosity that connects to unshaded part of glass at exterior side";
      Interfaces.RadiosityInflow JInUns_a 
        "Incoming radiosity that connects to unshaded part of glass at exterior side";
      Interfaces.RadiosityOutflow JOutSha_a if haveShade 
        "Outgoing radiosity that connects to shaded part of glass at exterior side";
      Interfaces.RadiosityInflow JInSha_a if haveShade 
        "Incoming radiosity that connects to shaded part of glass at exterior side";
    
      Interfaces.RadiosityOutflow JOutUns_b 
        "Outgoing radiosity that connects to unshaded part of glass at room-side";
      Interfaces.RadiosityInflow JInUns_b 
        "Incoming radiosity that connects to unshaded part of glass at room-side";
      Interfaces.RadiosityOutflow JOutSha_b if haveShade 
        "Outgoing radiosity that connects to shaded part of glass at room-side";
      Interfaces.RadiosityInflow JInSha_b if haveShade 
        "Incoming radiosity that connects to shaded part of glass at room-side";
    
      Buildings.HeatTransfer.Windows.BaseClasses.CenterOfGlass glaUns(
        final glaSys=glaSys,
        final A=AGla,
        final til=til,
        final linearize=linearize) "Model for unshaded center of glass";
    
      Buildings.HeatTransfer.Windows.BaseClasses.CenterOfGlass glaSha(
        final glaSys=glaSys,
        final A=AGla,
        final til=til,
        final linearize=linearize) if haveShade "Model for shaded center of glass";
    
      Modelica.Thermal.HeatTransfer.Components.ThermalConductor frame(G=AFra*
            glaSys.UFra) "Thermal conductance of frame";
    
      Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a glaUns_a 
        "Heat port at unshaded glass of exterior-facing surface";
      Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_b glaUns_b 
        "Heat port at unshaded glass of room-facing surface";
      Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a glaSha_a if haveShade 
        "Heat port at shaded glass of exterior-facing surface";
      Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_b glaSha_b if haveShade 
        "Heat port at shaded glass of room-facing surface";
    
      Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a fra_a 
        "Heat port at frame of exterior-facing surface";
      Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_b fra_b 
        "Heat port at frame of room-facing surface";
      Modelica.Blocks.Interfaces.RealInput uSha(min=0, max=1) if 
           haveShade 
        "Control signal for the shading device. 0: unshaded; 1: fully shaded (removed if no shade is present)";
        
    
      Modelica.Blocks.Interfaces.RealInput QAbsUns_flow[glaSys.nLay](each unit="W",
          each quantity="Power") 
        "Solar radiation absorbed by unshaded part of glass";
      Modelica.Blocks.Interfaces.RealInput QAbsSha_flow[glaSys.nLay](each unit="W",
          each quantity="Power") if haveShade 
        "Solar radiation absorbed by shaded part of glass";
    
    protected 
      final parameter Boolean haveShade = glaSys.haveExteriorShade or glaSys.haveInteriorShade 
        "Parameter, equal to true if the window has a shade";
    
      BaseClasses.ShadingSignal shaSig(final haveShade=glaSys.haveExteriorShade or glaSys.haveInteriorShade) 
        "Block to constrain the shading control signal to be strictly within (0, 1) if a shade is present";
        
    
    equation 
      connect(frame.port_a, fra_a);
      connect(frame.port_b, fra_b);
    
      connect(glaUns.glass_a, glaUns_a);
      connect(glaUns.glass_b, glaUns_b);
      connect(shaSig.yCom, glaUns.u);
      connect(shaSig.y, glaSha.u);
      connect(shaSig.u, uSha);
      connect(glaSha.glass_a, glaSha_a);
      connect(glaSha.glass_b, glaSha_b);
      connect(JInUns_a, glaUns.JIn_a);
      connect(glaUns.JOut_a, JOutUns_a);
      connect(glaUns.JOut_b, JOutUns_b);
      connect(JInUns_b, glaUns.JIn_b);
      connect(JInSha_a, glaSha.JIn_a);
      connect(glaSha.JOut_a, JOutSha_a);
      connect(glaSha.JOut_b, JOutSha_b);
      connect(JInSha_b, glaSha.JIn_b);
      connect(glaUns.QAbs_flow, QAbsUns_flow);
    
      connect(glaSha.QAbs_flow,QAbsSha_flow);
    
    end Window;
    

    Buildings.HeatTransfer.Windows.ExteriorHeatTransfer Buildings.HeatTransfer.Windows.ExteriorHeatTransfer

    Model for heat convection at the exterior surface of a window that may have a shading device

    Buildings.HeatTransfer.Windows.ExteriorHeatTransfer

    Information

    Model for the convective heat transfer between a window shade, a window surface and the room air. This model is applicable for the outside-facing surface of a window system and can be used with the model Buildings.HeatTransfer.Windows.Window.

    This model adds the convective heat transfer coefficient to its base model.

    Extends from BaseClasses.PartialConvection (Partial model for heat convection between a possibly shaded window that can be outside or inside the room).

    Parameters

    TypeNameDefaultDescription
    AreaA Heat transfer area of frame and window [m2]
    RealfFra Fraction of window frame divided by total window area
    BooleanlinearizeRadiation Set to true to linearize emissive power
    RealvieFacSky View factor from receiving surface to sky
    Shading
    EmissivityabsIRSha_air Infrared absorptivity of shade surface that faces air [1]
    EmissivityabsIRSha_glass Infrared absorptivity of shade surface that faces glass [1]
    TransmissionCoefficienttauIRSha_air Infrared transmissivity of shade for radiation coming from the exterior or the room [1]
    TransmissionCoefficienttauIRSha_glass Infrared transmissivity of shade for radiation coming from the glass [1]
    BooleanhaveExteriorShade Set to true if window has exterior shade (at surface a)
    BooleanhaveInteriorShade Set to true if window has interior shade (at surface b)
    BooleanthisSideHasShadehaveExteriorShadeSet to true if this side of the model has a shade

    Connectors

    TypeNameDescription
    input RealInputuShaInput connector, used to scale the surface area to take into account an operable shading device, 0: unshaded; 1: fully shaded
    HeatPort_aairPort that connects to the air (room or outside)
    HeatPort_bglaUnsHeat port that connects to unshaded part of glass
    HeatPort_bglaShaHeat port that connects to shaded part of glass
    HeatPort_aframeHeat port at window frame
    output RadiosityOutflowJOutUnsOutgoing radiosity that connects to unshaded part of glass [W]
    input RadiosityInflowJInUnsIncoming radiosity that connects to unshaded part of glass [W]
    output RadiosityOutflowJOutShaOutgoing radiosity that connects to shaded part of glass [W]
    input RadiosityInflowJInShaIncoming radiosity that connects to shaded part of glass [W]
    input RealInputQAbs_flowSolar radiation absorbed by shade [W]
    input RealInputvWinWind speed
    input RealInputTBlaSkyBlack body sky temperature [K]
    input RealInputTOutOutside temperature [K]

    Modelica definition

    model ExteriorHeatTransfer 
      "Model for heat convection at the exterior surface of a window that may have a shading device"
      extends BaseClasses.PartialConvection(final thisSideHasShade=haveExteriorShade);
      Modelica.Blocks.Interfaces.RealInput vWin "Wind speed";
      Buildings.HeatTransfer.Windows.BaseClasses.ExteriorConvectionCoefficient
        conCoeGla(                                          final A=AGla) 
        "Model for the outside convective heat transfer coefficient of the glass";
      Buildings.HeatTransfer.Windows.BaseClasses.ExteriorConvectionCoefficient
        conCoeFra(                                          final A=AFra) 
        "Model for the outside convective heat transfer coefficient of the frame";
     Radiosity.OutdoorRadiosity radOut(
       final A=AGla, vieFacSky=vieFacSky,
        linearize=linearizeRadiation) "Outdoor radiosity";
      parameter Real vieFacSky(min=0, max=1) 
        "View factor from receiving surface to sky";
      Modelica.Blocks.Interfaces.RealInput TBlaSky(
        final quantity="ThermodynamicTemperature",
        final unit="K",
        min=0) "Black body sky temperature";
      Modelica.Blocks.Interfaces.RealInput TOut(final quantity="ThermodynamicTemperature",
                                                final unit = "K", min=0) 
        "Outside temperature";
    equation 
      assert(-1E-10<vieFacSky and 1.00001 > vieFacSky,
             "View factor to sky is out of range. vieFacSky = " + String(vieFacSky)
             + "\n   Check parameters.");
    
      connect(vWin, conCoeGla.v);
      connect(vWin, conCoeFra.v);
      connect(conCoeFra.GCon, conFra.Gc);
      connect(conCoeGla.GCon, proSha.u1);
      connect(conCoeGla.GCon, proUns.u2);
      connect(radOut.JOut, radShaOut.JIn);
      connect(radOut.TBlaSky, TBlaSky);
      connect(radOut.TOut, TOut);
    end ExteriorHeatTransfer;
    

    Buildings.HeatTransfer.Windows.InteriorHeatTransfer Buildings.HeatTransfer.Windows.InteriorHeatTransfer

    Model for heat convection at the interior surface of a window that may have a shading device

    Buildings.HeatTransfer.Windows.InteriorHeatTransfer

    Information

    Model for the convective heat transfer between a window shade, a window surface and the room air. This model is applicable for the room-facing surface of a window system and can be used with the model Buildings.HeatTransfer.Windows.Window.

    This model adds the convective heat transfer coefficient to its base model.

    Extends from BaseClasses.PartialConvection (Partial model for heat convection between a possibly shaded window that can be outside or inside the room).

    Parameters

    TypeNameDefaultDescription
    AreaA Heat transfer area of frame and window [m2]
    RealfFra Fraction of window frame divided by total window area
    BooleanlinearizeRadiation Set to true to linearize emissive power
    Shading
    EmissivityabsIRSha_air Infrared absorptivity of shade surface that faces air [1]
    EmissivityabsIRSha_glass Infrared absorptivity of shade surface that faces glass [1]
    TransmissionCoefficienttauIRSha_air Infrared transmissivity of shade for radiation coming from the exterior or the room [1]
    TransmissionCoefficienttauIRSha_glass Infrared transmissivity of shade for radiation coming from the glass [1]
    BooleanhaveExteriorShade Set to true if window has exterior shade (at surface a)
    BooleanhaveInteriorShade Set to true if window has interior shade (at surface b)
    BooleanthisSideHasShadehaveInteriorShadeSet to true if this side of the model has a shade

    Connectors

    TypeNameDescription
    input RealInputuShaInput connector, used to scale the surface area to take into account an operable shading device, 0: unshaded; 1: fully shaded
    HeatPort_aairPort that connects to the air (room or outside)
    HeatPort_bglaUnsHeat port that connects to unshaded part of glass
    HeatPort_bglaShaHeat port that connects to shaded part of glass
    HeatPort_aframeHeat port at window frame
    output RadiosityOutflowJOutUnsOutgoing radiosity that connects to unshaded part of glass [W]
    input RadiosityInflowJInUnsIncoming radiosity that connects to unshaded part of glass [W]
    output RadiosityOutflowJOutShaOutgoing radiosity that connects to shaded part of glass [W]
    input RadiosityInflowJInShaIncoming radiosity that connects to shaded part of glass [W]
    input RealInputQAbs_flowSolar radiation absorbed by shade [W]
    input RadiosityInflowJInRooIncoming radiosity of window construction [W]
    output RadiosityOutflowJOutRooOutgoing radiosity of window construction [W]
    HeatPort_ashaHeat port to shade

    Modelica definition

    model InteriorHeatTransfer 
      "Model for heat convection at the interior surface of a window that may have a shading device"
      extends BaseClasses.PartialConvection(final thisSideHasShade=haveInteriorShade);
      Buildings.HeatTransfer.Windows.BaseClasses.InteriorConvectionCoefficient
        conCoeGla(                                          final A=AGla) 
        "Model for the inside convective heat transfer coefficient of the glass";
      Buildings.HeatTransfer.Windows.BaseClasses.InteriorConvectionCoefficient
        conCoeFra(                                          final A=AFra) 
        "Model for the inside convective heat transfer coefficient of the frame";
    
      Interfaces.RadiosityInflow JInRoo "Incoming radiosity of window construction";
      Interfaces.RadiosityOutflow JOutRoo 
        "Outgoing radiosity of window construction";
    
      Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a sha if 
          windowHasShade "Heat port to shade";
    equation 
      connect(conCoeFra.GCon, conFra.Gc);
      connect(conCoeGla.GCon, proUns.u2);
      connect(conCoeGla.GCon, proSha.u1);
    
      connect(JInRoo, radShaOut.JIn);
      connect(JInUns, JOutRoo);
      connect(shade.JOut_air, JOutRoo);
      connect(shade.sha, sha);
    end InteriorHeatTransfer;
    

    Automatically generated Wed Feb 22 15:23:18 2012.