One thing confusing me until now is that the efficiency of heatpipe based coolers.

When heatpipe based coolers first introduced for mainstream usage, the explanation was that the liquid inside the pipes have very low boiling temperature thus it will evaporate under certain temperature level. The evaporated liquid which brings heat moves to the top of the pipe, which then gets cool or condensed and flows back down to the hotter part.

To make it simple, it's the liquid inside the pipes which mainly does the job.

I have a few doubts in mind.

1. Isn't that the way the heatpipe works supposed to be following the gravity law? Hot air goes up, and when it's cold, it goes down (cold air heavier than hot air)? Or do they just move from hot area to cold area like how air supposed to work in the atmosphere? I have seen many heatpipe based cooler which when we put inside the casing, the orientation is not upright, instead, the heatpipe end points toward outside of the casing, away from its base. While in many reviews, usually the person who did the review lay down their system flat instead of putting the heatsink inside the casing.

2. How efficient is the liquid inside the heatpipe? How much thermal energy can they dissipate compare to a normal copper cooler with good fan?

thats a question ive been keen on finding out the answer to as well.

thing is, with current heatpipe technology, i.e. something from Artic Cooling for example... i have yet to see different temperature scores from both vertical or horizontal orientations. The scores to vary, but by 1-2 degrees celcius only, just enough to fall within the acceptable margin of error.

probably because the heatpipes are used are too small, and too short. Maybe with something thicker and longer, we will see gravity taking effect?

thy r liquid inside heatpipes?

1) Newer heatpipes have wicks inside to balance off the heat goes up effect. Having said so....sideways is ok...up is better. Down is rather not.

2) like the bola says...depends on size. Different ratings for different size. But the whole point of heatpipe as the name implies is to pipe the heat away from the source.

http://www.avc.com.tw/products/nb-thermal/66.htm

Let's say:

a) Traditional SLK type heatsink....damn best but then ya need a strong fan (strong pressure) to block into the gaps between the fins.

b) Heatpipe cooler....pipes the heat away from the base to the outer parts of the fins where ya get better effect from slower fans

This post has been edited by sniper on the roof: Jul 9 2006, 02:30 PM

tower heatsinks "U" and Zalman 9500 "8" are so far the best shape for heatpipe.
as long as they are not disorientated in such away that the base is located on the highest point of the heatsink, then it shouldnt be a problem......

and the " liquid " inside is so little that they'll evaporate if you poke it.
it's just meant to wet the wick structure and not to flood them

OK... now I understand....

but still.... do heatpipes really able to transfer a lot of thermal energy that fast?

This post has been edited by soulfly: Jul 9 2006, 11:48 PM

yeap......the wick structure is really important.......

and who says that it doesnt rely on gravity to work ?

it will only work best under gravity

Ah , simple analogy will do ... Liquid can move while Solid can't ....

All the heat traped by the liquid will be brought to a cooler place to dissipate the heat by cappilary action or convection or depressurization ......Hence less time .

While , Metal as Stationary phase need more time to overcome thermal resistance to transfer by conducting heat from Hot area to cold area ..

The time make the diffrence , Liquid Heatpipe have faster inner heat transfer ....