Seeking "right" formula for heat dissipation.

[Wally89]

Hi, I'm struggling to find a univocal answer to my problem.

I have an electric enclosure, I calculated that when outside is 35°c the inside temperature is 76°C

How do I calculate the necessary air flow to bring the internal temperature down to the ambient one (35°c)?

Thanks in advance.

 

[itsmoked]

You mean punching two holes in the enclosure so the ambient can circulate?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[IRstuff]

Mathematically, short of an infinitely fast air flow through the holes Keith mentioned, there will always be a temperature rise, even if it's infinitesimally small. If you've done calculations, then you can use the specific heat of air and determine the amount of air mass-flow to raise the temperature by, say, 1ºC, given your power dissipation.

For example, a 1ºC temperature rise requires a minimum of 173 cubic feet/minute flow with 100W input.

trying to design for no temperature is unrealistic and expensive. Your components should already be rated for at least 70ºC

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[MortenA]

I would ignore the temperature you calculated baser on heat transfer and use the energi you need to Remove and the heat capacity of the Air. If Q is the heat generated, V is vol flow of air c is the volume heat capacity of air and t is the max temperature you will allow then V=Q/c/(t-35)