A solar calculator model providing models for the solar direction and solar loads.
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A solar calculator model providing models for the solar direction and solar loads.
Available models for the solar direction:
constant: Constant sunbeam direction.tracking: Transient model calculating sunbeam direction based on a given set of parameters.
Available models for the solar load:
constant: Constant solar load.timeDependent: Time-dependent solar load.fairWeather: Solar fluxes are calculated following the "Fair Weather Conditions Method from the ASHRAE Handbook".theoreticalMaximum: Theoretically maximum solar load.
- Usage
- Minimal examples by using
constant/radiationProperties:
sunDirectionModel - Option-1:
solarLoadCoeffs
{
sunDirectionModel constant;
sunDirection (1 0 -1);
}
where the entries mean:
| Property | Description | Type | Reqd | Deflt |
sunDirection | Sunbeam direction | vector | no | calculated |
sunDirectionModel - Option-2:
solarLoadCoeffs
{
sunDirectionModel tracking;
sunTrackingUpdateInterval 800;
localStandardMeridian 9;
startDay 204;
startTime 15;
longitude 139.74;
latitude 35.658;
gridUp (0 0 1);
gridEast (1 0 0);
}where the entries mean:
| Property | Description | Type | Reqd | Deflt |
sunTrackingUpdateInterval | Interval to update the Sun direction [decimal hours] | scalar | yes | - |
localStandardMeridian | GMT (Local Zone Meridian) [decimal hours] | scalar | yes | - |
startDay | Day from 1 to 365 | scalar | yes | - |
startTime | Start time for the Sun position [decimal hours] | scalar | yes | - |
longitude | Geographic coordinate specifying the east–west position of a point on the surface of a planetary body [degree] | scalar | yes | - |
latitude | Geographic coordinate specifying the north–south position of a point on the surface of a planetary body [degree] | scalar | yes | - |
gridUp | Grid orientation upwards | vector | yes | - |
gridEast | Grid orientation eastwards | vector | yes | - |
sunLoadModel - Option-1:
solarLoadCoeffs
{
sunLoadModel constant;
directSolarRad 100;
diffuseSolarRad 0;
}where the entries mean:
| Property | Description | Type | Reqd | Deflt |
directSolarRad | Direct solar irradiation [W/m2] | scalar | yes | - |
diffuseSolarRad | Diffuse solar irradiation on vertical surfaces [W/m2] | scalar | yes | - |
sunLoadModel - Option-2:
solarLoadCoeffs
{
sunLoadModel timeDependent;
directSolarRad <Function1<scalar>>;
diffuseSolarRad <Function1<scalar>>;
}where the entries mean:
| Property | Description | Type | Reqd | Deflt |
directSolarRad | Time-series of direct solar irradiation [W/m2] | Function1<scalar> | yes | - |
diffuseSolarRad | Time-series of diffuse solar irradiation on vertical surfaces [W/m2] | Function1<scalar> | yes | - |
sunLoadModel - Option-3:
solarLoadCoeffs
{
sunLoadModel fairWeather;
skyCloudCoverFraction 0.25;
groundReflectivity 1.0;
A 0.1;
B 0.2;
C 0.058;
beta 0.15;
}where the entries mean:
| Property | Description | Type | Reqd | Deflt |
A | Apparent solar irradiation at air mass m = 0 | scalar | yes | - |
B | Atmospheric extinction coefficient | scalar | yes | - |
C | Solar diffusivity constant | scalar | yes | - |
groundReflectivity | Ground reflectivity | scalar | yes | - |
skyCloudCoverFraction | Fraction of sky covered by clouds [0,1] | scalar | no | 0 |
beta | Solar altitude (in degrees) above the horizontal | scalar | no | calculated |
In this model the flux is calculated as:
directSolarRad = (1 - 0.75*skyCloudCoverFraction^3)*A/exp(B/sin(beta));
sunLoadModel - Option-4:
solarLoadCoeffs
{
sunLoadModel theoreticalMaximum;
Setrn 1.0;
SunPrime 4.0;
groundReflectivity 1.0;
C 0.058;
}where the entries mean:
| Property | Description | Type | Reqd | Deflt |
Setrn | Parameter in maximum theoretical direct solar model | scalar | yes | - |
SunPrime | Parameter in maximum theoretical direct solar model | scalar | yes | - |
groundReflectivity | Ground reflectivity | scalar | yes | - |
C | Solar diffusivity constant | scalar | yes | - |
In this model the flux is calculated as:
directSolarRad = Setrn*SunPrime;
- Note
- The
sunDirectionModel:tracking can only be used in transient calculations.
- The keyword
sunTrackingUpdateInterval (in hours) specifies on which interval is the Sun direction updated.
- The diffuse on vertical/horizontal walls and ground-reflected radiation are calculated following the ASHRAE Handbook.
- The range of
skyCloudCoverFraction is [0,1].
- Source files
-
Definition at line 440 of file solarCalculator.H.
1.8.17