Radiative Heat Transfer

Simon Neuner

Dear Experts,

 

I am currrently carrying out thermal analysis in AcuConsole on a photovoltaic panel composed of five different layers (Glass cover, encapsulant, silicium cell, encapsulant, Backsheet). I want to consider thermal radiation on the front& back surface of my PV panel according to the following equations for the front and back surface, respectively:

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I read in the AcuConsole training manual that calculation of radiation is only possible from surfaces of fluid mediums but I have no fluid in my simulation setup. Therefore my questions are:

 

1.) Is there any other possibility to implement radiation without a fluid volume (i.e. setting heat flux (boundary condition) to -100 W/m^2 on the corresponding surface)?

 

2.) The equations above are dependent on a value which has to be calculated by the processor (Trear and Tfront). Is it possible to formulate such boundary conditions that depend on values that will be calculated later by the processor (AcuSolve)?

 

Thanks in advance!

acupro

I believe you would apply Element Boundary Condition for Radiation Heat Flux.  Use BC* in the left-hand panel, then for each surface, go into Advanced Options and Element Boundary Conditions.  Activate Radiation Heat Flux, of type = constant.  For the constant value, use Epsilon * F * Sigma, and indicate the Reference Temperature (T_sky or T_ground).  Not sure what is F in your equation - but you'll need to include that in your constant value.

Simon Neuner

Altair Forum User said:

I believe you would apply Element Boundary Condition for Radiation Heat Flux.  Use BC* in the left-hand panel, then for each surface, go into Advanced Options and Element Boundary Conditions.  Activate Radiation Heat Flux, of type = constant.  For the constant value, use Epsilon * F * Sigma, and indicate the Reference Temperature (T_sky or T_ground).  Not sure what is F in your equation - but you'll need to include that in your constant value.

 

Dear @acupro, thank you for your advice! 

 

F in the above equation denotes the view factor, i.e. a 'geometric' quantity of how the front or rear surface of the solar panel is oriented towards the sky or ground.

 

Can you specify which equation is used to describe thermal radiation in this case ( through the boundary conditions) or is taken into account in the overall energy equation? And is the surface temperature Trear/Tfront considered by the solver in my equation from above?

acupro

The radiation is taking into account with the overall energy equation, via the boundary condition.  From the Command Reference Manual:

You would apply the Element Boundary Condition separately to each surface, to add that radiation heat flux calculation to that particular surface, and AcuSolve will handle that appropriately.