i am trying to design an efficient cooling solution for my project.
I planned placing a IoT computer in an aluminum housing which is completely closed.
In this case, do I really need fins and large surface areas INSIDE the aluminium housing when my main goal is to dissipate the heat to the housing itself as fast as possible?
I'd really appreciate your help!
Here is some more information:
Ambient temperature: 25-30 degrees celsius
Max. Power: 10W
Time Period: The device is intended to work 24/7 (of course NOT with max. Power but with 20-30% of what's possible. However I think that a great product is designed to also handle 100% Power over a vast period of time!
Internal temperature: The CPU itself (surface area of 10mm x 10mm) reaches a max of 80 degrees.
Surface area of the enclosure: 0,05735 m2
Enclosure material: Aluminium sheet metal (1mm thickness)
Space between CPU and inside of the enclosure: 14mm
Maximum Volume of the Heatsink: 60cm3
Best Answer
There are two power functions you need to be concerned with: instantaneous power dissipation, and long term power dissipation. A large thermal mass (finned or not) will prevent your IC overheating due to a quick spike of power. Over the longer term, the heat needs to be dissipated to the outside environment. Fins are only effective if there is some airflow to remove the heat - this could be by simple convection or by forced flow (fan). In a sealed case, convection will be reduced compared to free air and a fan will also be much less effective.
For your case, if you don't get sufficient cooling from just normal internal convection, I would have a metal block from the top of the heat dissipating commponents to the case itself. That way, you increase the thermal conductance to the case. If you still have a problem with heating, then you could put fins on the outside of the case, which is presumably in free air.