Heat dissipation using FEM

About the development of the FEM module/workbench.

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paddle
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Heat dissipation using FEM

Post by paddle »

Hey guys,
I'm working on a desk PC design.

It has a CPU/GPU which are cooled by a special heatsink which is as follow :
- Bottom of the desk panel which is a 2mm aluminum sheet
- Heatsinks applied on CPU and GPU which act as a bridge for the heat to transfert it from the CPU/gpu to the sheet.
- One massive heatsink with 12 40*40 fans.
fem.png
fem.png (410.03 KiB) Viewed 2506 times
I wanted to simulate to see if that heatsink concept will dissipate the heat correctly.

So I started by making a boolean operation to put all those aluminum parts together in one body. (not sure if that was necessary?)

I tried to follow this tutorial : https://www.youtube.com/watch?v=hUS7T9hrn4k
But I run in several issues:
- The body being a little bit complex, the created mesh has so many faces that it's hard to compute.
- Aluminum material doesn't have an expansion coefficient set in. So trying Calculix throw an error on that.

But no having a expansion coefficient is OK for me. Because I don't care about the deformation, just by the heat dissipation.

And even if I modify the aluminum material to add a expansion coefficient, I fear that computing it will not be possible.

So I'm thinking that I may be missing something easier to just get the temperatures without deformation.

Also is it possible to simulate fans/air flows?

Thanks !
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NewJoker
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Re: Heat dissipation using FEM

Post by NewJoker »

You should definitely simplify this model - remove all the features that are not likely to have a significant impact on the results, such as these small holes. In fact, similar structures (like PCBs) are often analyzed in terms of heat transfer with small components reduced to cuboids or cylinders.

You are trying to perform thermal stress analysis for which expansion coefficient is needed. Instead of that, you should run a pure heat transfer study. CalculiX supports it but you will have to manually edit the input file after exporting it from FreeCAD.
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Kunda1
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Re: Heat dissipation using FEM

Post by Kunda1 »

Mod edit: moved to FEM subforum
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Laurie Hartley
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Re: Heat dissipation using FEM

Post by Laurie Hartley »

I know material expands and contracts but that is about it :) but I like to watch Bugman's tutorials on YouTube.
His latest video happens to be about this particular subject:

https://youtu.be/k_J1TRW5K4E

Then I came across your post which seems quite coincidental so I decided to respond.

I usually slow the video speed down to see what he is up to.
He seems to be addressing the questions about material at about 3:30.

I hope this may be of assistance to you if not - no harm done.
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