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How do heatpipes work?

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Fire58Mech

Member
Joined
Feb 13, 2004
Location
PA
I looked in how stuff works. com and nothing. So I thought i'd ask you guys. How do heat pipes work. What are the advatiges and what are the disadvantiges. If I were to get one what kind should I get?

Thanks
 
Heat pipes have a working fluid usally under low pressure. This fluid, as a liquid is mostly aborbed in a wick within the pipe. When this fluid is heated above room temperature it vaporizes out of the wick. This has two affects. First, the pressure in the wick decrease which draws cool liquid to the source of heat. Second, the pressure outside the wick increases pushing the heated vapor away. When the vapor cools it condenses into a liquid which is absorbed by the wick and has the opposite affect as the hot end. Heated vapor is drawn toward the cool end and cooled liquid is pushed away from the cool end.

The also benefit from gravity since the vapor is less dense than the liquid.

Overall, the heat transfers faster than it could through solid copper.
 
there are also solid heatpipes consisting of nothing more than metal.

The general idea of heatpipes is heat TRANSFER and relocation.

Heatpipes use either solid or liquid described in the previous post to move the heat to another area for it to be dissipated...

The heatpipe itself does not have much surface area becuase the purpose is to move the heat not dissipate it. Once its moved to another area it is dissipated there.
 
heat_pipe_illustration.jpg

this image has been linked to SOOO Much.

basicly. a heatpipe is a sealed tube. all the air is sucked out and a small amount of fluid is injected into the tube, called the working fluid.
What happens, is when you take away all the air, you create a vacumm in the tube, which creates a different atmospheric condition for the fluid inside.
the atmospheric pressure of the tubes innards is less than the atmospheric pressure outside it.
what this does, is allow the fluid that is inside the pipe, to boil at a lower temperature when heat is applied.
lets say you try to boil water.. it boils at 213º F right? if you remove some of the pressure pushing down on it, you can boil it at a lower temperature.

when you boil a fluid, it collects energy in the form of heat, which is able to move freely away from the source, as a vapour.

heat wants to equalize, so when you give it someplace that is colder to go, it will. the other end of the heapipe has a heatsink attached to it, and this lowers the temperture of the working fluid enough that it can recondense into a liquid. it is then collected into a wick, and returned to the evaperator side.

all a heatpipe does is MOVE the heat through the phase change of a chemical. it isnt as efficiant as direct metal to metal conduction, but it allows you to move heat over much greater distances than you could with a solid heatink.
it is ideal for conditions where a heatsink cant always be applied.

Thermalright makes heatpipe heatsinks that are just, heatsinks, with heatpipes to move heat from the base to the top where the heatsink is coldest.
sp971.jpg


other heatpipe applications have much longer heatpipes that move the heat to a completly different location

http://www.nordichardware.com/reviews/cooling/2003/ZalmanTNN500A/
 
It just use phase change material inside. Heat vaporizes (alcohol is example) on one end . Hot Vapor condenses on the cold end . sometimes there is a wicking material inside to get the liquid back to the hot end. Advantage are: they are really vapor ware, no hardware involve, no breakdown, no energy cost . They scale up nicely and work even better. Example: They use them on the Alaskan Oil pipe line . There they pump underground heat to keep the above pipeline Hot to keep it flowing. Really no downside to it . Check the internet alot of people make them and the one you want going to depend on your application
 
Sorry I didn't respond sooner. Bin afully busy. Thanks for the info, learned alot. bumb
 
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