Learning Forum

[satishlukka]

I want to simulate simultaneous radiation and convection inside a enclosure. Iam trying to do this in 2D.

Description of case : There are two cylinders one inside the other. Inner cylinder is generating heat. Heat is being transferred from inner cylinder to outer cylinder through radiation and convection.

[ErKo]

Hi
The ansys solver would not calculate that (temperature inside cavity).
This would require something different if you want to account for the air inside.

Fluent might be able to do this (radiation and convection) of an enclosure.

This would if possible provide the most accurate results I would imagine, but if one can not run such high fidelity CFD analysis then perhaps the below might help.

I have seen that an equivalent thermal resistance/conductivity of the air gap/cavity inside an enclosure can be used for the air inside the cavity say in insulated glass units (e.g., double glazing). Then we need to actually model/mesh the air inside the cavity and we apply an equivalent thermal conductivity (material property in engineering data) to that air inside the cavity (then we do not need any radiation and convection boundary conditions of course). This paper shows a bit how to get equivalent values for radiation and convection heat transfer (Search for this title: Prediction and Analysis of the Thermal Performance of Composite Vacuum Glazing, or this paper: Development of Numerical Heat Transfer and the Structural Model to Design Slim and Translucent Vacuum Layer Type Insulation Panels to Retrofitting Insulation in Existing Buildings). Of course it does not model the natural convection and all other details that might occur inside a cavity, but it might be ok to get an idea of the heat loss for certain type of applications (like double glazed units).
So these are the only two correct option that we can propose in order to do this accurately.
All the best

Erik

[satishlukka]

Actually how to use SURF151 element in 2D heat transfer for finding average bulk temperature of fluid(solver calculates it by thermal equilibrium of model).