Does gravity effect heat ?

[coolroyboy2]

Most motherboards and processers are mounted verticaly , does heat always travel up ? If heat always rises why not place the majority of the heat transfer area above the sorce of the heat ? The reason I ask is most all heatsinks I have seen are made as if they will be mounted flat . Would a small change in design aid in cooling the modern processers most of us have ?

 

[mooncancook]

It's not heat that travels up, it's the hot air that carries the heat travels up. I don't think it'll make any noticeable improvement. It is the ventilation of air that makes the biggest diffence i think. Having a fan to blow air to carry the heat away from the CPU is most important.

 

[ScottMac]

Hot air rises because the air is less dense than the cooler air.

Without gravity / in microgravity, there is no convection; a flame is just a little ball around the source.

I watched a NASA demonstration at OshKosh that showed this pretty well. A small candle was placed in a sealed box with a video camera. The box was hoisted up about 8 feet or so, then dropped. The camera recorded the flame as the box was in freefall. The flame went from the usual yellow oval with a blue core around the wick to a small blue ball around the wick.

It was a good demo, the guy doing the demo is part of a NASA group that studies things like fires in space vehicles and related sciences.

FWIW

Scott

 

[VictorLazlo]

Mount your heatsink vertically like normal, and then take two temp probes and put one at the bottom and one at the top. See if the heatsink fins at the top get hotter than the fins at the bottom.

 

[Sahakiel]

Infrared is electromagnetic.
Therefore, heat is affected by gravity.
How much?
Probably not enough to warrant the exertion required to think this up.

 

[Mday]

Originally posted by: Sahakiel
Infrared is electromagnetic.
Therefore, heat is affected by gravity.
How much?
Probably not enough to warrant the exertion required to think this up.

yup, but hot air still rises, cuz hot air is matter.

 

[Georgeisdead]

From a practical standpoint, and in this case particulalry, always remember that heat is transferred DOWN a temperature gradient. That is, heat is tranferred FROM a hot source TO a cooler source and not vice versa. In an abstract theoretical argument, gravity may play some role, but any gravitational effects on heat transfer are dwarfed by heat transfer from the hot heatsink to the cooler air. The more pertinent issue here is the density of air as a function of temperature. In a computer case, there is not a big enough altitude change to say that the air at the top of the case is necessarilly cooler than the air at the bottom of the case. But, regardless, heat energy will be transferred to whatever source is cooler than the hot source. In a computer case, the surrounding air is the cold source and gravity has no effect at all. Now in space, or in a perfect vacuum, that can become a different story entirley. But here, on earth, in a computer case, the mechanisms of heat transfer are not affected by gravity. That is I am simply saying gravity does not "pull heat" down in a computer case. Heat is always tranferred from hot to cold in its simplest sense.