Heat transfer through airgaps

szicsa

Hi All,
I would like to analyse a simple 2d heat tranfer through a wall made up by different layers. I know how to do the first solid layer but don't know how to deal with the airgap between the two layers.
Is there anyone to know a solution?

Victor

Hello szicsa

Mecway can't model general surface-to-surface convection or radiation so you would have to model it as an equivalent conduction through a layer of material.

If you use the CCX solver, you can connect them with contact and define a thermal conductance instead of having mesh in the air gap.

If you have forced convection with a known mass flow rate, say parallel to the walls, you might be able to use the forced convection features with 3-node fluid network elements to represent the fluid flow.

szicsa

Thank you Victor. It is very useful. It is a closed space in a wall. No forced ventilation.
Do you know any literature or directions to find a value for equivalent values?

JohnM

For thin gaps try air conduction - try extruding normal off surface and then project new nodes onto the mating surface For larger trapped air volumes, use the forced convection feature - create an internal node, select internal surface for convection, try h=10W/m2/K, calibrate with test.