modelZoneLwGainDistribution
Information
This model computes how radiative gains are redistributed among all surfaces. We consider 1) diffuse solar gains, 2) beam solar gains and 3) other, long wave, internal gains, e.g. from occupants.
Diffuse solar gains are redistributed by computing a weighting factor equal to the surface area multiplied with the shortwave emissivity of the surface. This factor is used to redistribute the diffuse solar gains among all surfaces.
Internal gains from occupants are redistributed in the same way, but using the long wave emissivity instead of the short wave emissivity.
Direct/beam solar gains are redistributed by assuming that a fixed fraction of the beam solar gains are absorbed by the floor. This fraction equals the short wave emissivity of the floor. If there are multiple floors (based on the inclination angle) then their area and emissivity are used to compute a weight factor for the floors. The remaining radiation is redistributed over all other surfaces, again using the shortwave emissivity and surface area to determine the relative fractions. If there is no floor then the beam radiation is spread over all surfaces and a warning is generated.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Integer | nSurf | number of surfaces in contact with the zone | |
| Advanced | |||
| Boolean | lineariseJModelica | false | =true, to introduce radiative temperature node |
| Modelica.Units.SI.Time | tau | 120 | Time constant for radiative node |
| Modelica.Units.SI.Temperature | T_start | 296.15 | Start value of radiative temperature node |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a | iSolDir | Direct solar radiation gains received through windows | |
| Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a | iSolDif | Diffuse solar radiation gains received through windows | |
| Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a | radGain | External long wave internal gains, e.g. from radiator | |
| Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_b | radSurfTot | Port for connecting to surfaces | |
| Modelica.Blocks.Interfaces.RealOutput | TRad | Radiative zone temperature, computed as weighted sum of surface temperatures. | |
| Modelica.Blocks.Interfaces.RealInput | epsLw | Long wave surface emissivities of connected surfaces | |
| Modelica.Blocks.Interfaces.RealInput | epsSw | Short wave surface emissivities of connected surfaces | |
| Modelica.Blocks.Interfaces.RealInput | area | Surface areas of connected surfaces | |
| Modelica.Blocks.Interfaces.RealInput | inc | Surface inclination angles | |
| Modelica.Blocks.Interfaces.RealInput | azi | Surface azimuth angles |
Revisions
-
July 21, 2020 by Filip Jorissen:
AddedgetInstanceName()in asserts. -
November 5, 2018 by Filip Jorissen:
Added initial equation forTRad. -
October 7, 2018 by Filip Jorissen:
Improved documentation. -
March 28, 2018 by Filip Jorissen:
Added option for introducing state for radiative temperature. -
December 22, 2016 by Filip Jorissen:
Fixed bug in absorption model whereTRadwas computed using coefficients foriSolDirinstead ofiSolDif. Added asserts for checking the sum of all weight factors. This closes #605. -
September 8, 2016 by Filip Jorissen:
Added warning for when there are no floors and guarded against division by zero. -
July 15, 2016 by Filip Jorissen:
New absorption model for beam radiation. -
July 12, 2016 by Filip Jorissen:
Simplified implementation by removing intermediate variables.