2-second question: Heat Distribution within a two part system

[thorn00]

If you could walk me through the process of setting up the problem, i would be extremely grateful. Say it's just a two parts touching each other (different materials), and they are both initially at room temperature (293K), then they are placed in a chamber where the air is 393K. How do i see the heat transfer through these materials?

-Thorn

 

[Brodie79]

Hi Thorn,

This would be easier (and more accurate) with a CFD package but you can get reasonable results using Cosmos.

There are two approaches to solving this problem the first would be to model a air volume around your two components. Then set-up a transient thermal study applying an initial temperature to all the components to be placed in the chamber at ambient and then a initial temperature of the chamber at 393K to the air volume. Then apply a temperature constraint to the air volume of 393K to represent the chamber.

You would then run the transient study and see the results.

The second method would be not to model the air volume but apply a convection coefficient to the components to represent your chamber. This would require you to know some information about the chamber such if it has forced convection and the power and so on.

The first method is very idealised and might not give you completely accurate results depending on your chamber. The second method requires you to know some properties of the chamber your using.

 

[corus]

Not sure why you'd need CFD unless it was a relatively small chamber where the air temperature changed as heat was lost to the materials, but then you'd need to know what happened outside the chamber too. The normal approach is to assume radiation to the surrounding chamber walls and natural convection to the air. This temperature dependent heat transfer coefficient can be found in most references. The problem is then a simple transient where only the materials are modelled, possibly in only 2D.

corus

 

[Co]

Good comments above. I solved it as a CC (convection-conduction) problem in comsol. This could also be done by hand, but it takes 5min if you only need it for simulation/illustration purposes.
I attached an animation for you.

cheers,

coppola

 

[Co]

btw, the left block is aluminum and the right is titanium. They are within air initially at a higher temperature. Just a comparison. You can see how differently the temperature distribution propagates on the left compared to the right.....