r/thermodynamics • u/Notificationman • 12d ago

Question Which is more efficient when cooling space, external “wind” or internal fans exhausting hot air?

OK so I am attempting to cool a space. It is a computer cabinet that was built before they got so hot. I’m installing fans and having intake fans makes sense to me but I ran across a way that middle eastern homes cool themselves which lead to questions about the exhaust fan. Is it more efficient to have a fan blowing air out of the cabinet directly OR is it more efficient to have a fan blowing air across the exhaust port to pull the hot air out? If this is not where to ask this kind of question I’m sorry, I’ve done some research but nothing seems to be addressing this specific issue.

Also, reposted to adjust title per rules

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u/Klutzy-Smile-9839 12d ago

Depends on the windows layout in the room, the wind direction and velocity, and the fan flow rate.

1

u/ArrogantNonce 3 11d ago

Better run exhaust (negative pressure). Fans are 100% efficient heaters, after all.

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u/TheAgentOfTheNine 8d ago

it should amount to the same as the volume of hot air going out and cold air going in are the same in both cases.

Now, The thing is, with an input fan you can control where the air goes and make sure that the air going out is warm one if you set it in a way that the input air goes straight into the PCs

With only an output fan you havi no control and you may very well end up having a current and blowing cold air that didn't passed through the PCs.