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Heatsink/ Heat Pipe / ThermoSiphon Cooling The cat will only make the mistake of putting its paw by your HSF once. :) Also the place to discuss the new high end heat pipe goodness. |
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#1 |
Cooling Neophyte
Join Date: Oct 2005
Location: evanston
Posts: 41
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I was wondering if any of you know a good source for heat pipes or heatplanes (the flat versions of heat pipes)? They would need to be short to the length of 10-12cm and with a small diameter. Any thoughts?
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#2 | |
Put up or Shut Up
Join Date: Dec 2001
Location: Spokane WA
Posts: 6,506
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#3 |
Cooling Savant
Join Date: Aug 2005
Location: uk
Posts: 400
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zalman hard drive coolers
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#4 |
Cooling Savant
Join Date: Jan 2003
Location: Sydney, Oz
Posts: 336
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More reading required. Heat pipes are quite specific in their working temperature range and also their wattage capabilities.
__________________
Long Haired Git "Securing an environment of Windows platforms from abuse - external or internal - is akin to trying to install sprinklers in a fireworks factory where smoking on the job is permitted." (Prof. Gene Spafford) My Rig, in all its glory, can be seen best here AMD XP1600 @ 1530 Mhz | Soyo Dragon + | 256 Mb PC2700 DDRAM | 2 x 40 Gb 7200rpm in Raid-0 | Maze 2, eheim 1250, dual heater cores! | Full specifications (PCDB) |
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#5 |
CoolingWorks Tech Guy Formerly "Unregistered"
Join Date: Dec 2000
Location: Posts: 2,371.493,106
Posts: 4,440
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also their internal volume, cannot be 're-bent' as volume dictates the charge
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#6 |
Cooling Savant
Join Date: Aug 2005
Location: uk
Posts: 400
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heatpipes are quite easy to model using 1D FEA analysis however the problem is degration with time is kinda complicated.
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#7 |
CoolingWorks Tech Guy Formerly "Unregistered"
Join Date: Dec 2000
Location: Posts: 2,371.493,106
Posts: 4,440
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FEA is Greek to DIY (someone looking for a source)
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#8 | |
Cooling Savant
Join Date: Jan 2003
Location: Sydney, Oz
Posts: 336
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What causes the degregation, and how marked is the effect? Down to 50% of initial performance over what time frame? How big a drop over, say, 5 years?
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Long Haired Git "Securing an environment of Windows platforms from abuse - external or internal - is akin to trying to install sprinklers in a fireworks factory where smoking on the job is permitted." (Prof. Gene Spafford) My Rig, in all its glory, can be seen best here AMD XP1600 @ 1530 Mhz | Soyo Dragon + | 256 Mb PC2700 DDRAM | 2 x 40 Gb 7200rpm in Raid-0 | Maze 2, eheim 1250, dual heater cores! | Full specifications (PCDB) |
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#9 |
Cooling Savant
Join Date: Aug 2005
Location: uk
Posts: 400
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I can’t find the link anymore. It came up on google when i was searching for other stuff. It was from an engineering product website. Though I doubt the engineering integrity of the site as the marketing guys might have got to it.
It said heatpipes are very good but there are problems with them apparently. The cause of them mucking up seems to be residue due to the phase change. The effect happens of the order of years but after about 5 years or so there could be problems. FEA = finite element analysis. Which is splitting an object up into blocks and then analysing the forces on each block using elementary procedures. This (well its a version of FEA called finite volume analysis where you measure the flow in and out of a block) can be used in full 3d to model heatpipes but the model is computationally expensive (that high end X2 is not leet enough) and presents problems. This is because the flow is two phase (gas and fluid) and highly temperature and energy dependent. The FEA program mentioned above uses the 1d assumption. Which uses an empirical / analytical method to calculate how a heat pipe would behave over a short section (where what defines short is actually rather complicated). It then uses many of these sections to model the heat transfer of the pipe to a solid section (ie a heatsink model). |
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#10 |
Cooling Savant
Join Date: Aug 2005
Location: uk
Posts: 400
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found it
http://www.crtech.com/heatpipe.html can't find the bit where it mentions heatpipes being blocked up. |
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#11 |
CoolingWorks Tech Guy Formerly "Unregistered"
Join Date: Dec 2000
Location: Posts: 2,371.493,106
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Thermacore has a mktg spiel on heat pipe reliability
before I would conclude that all . . . . (not gonna catch 'em all with the same net) |
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#12 |
Cooling Savant
Join Date: Aug 2005
Location: uk
Posts: 400
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Had a little search on Inspec and compendex (research paper databases)
This paper: THE ALUMINUM FLAT HEAT PIPE USING CYCLOPENTANE AS WORKING FLUID Takahiro Shimura, Hitoshi Sho and Yoshio Nakamura The Furukawa Electric Co., Ltd. Ecology & Energy Laboratory 2002 Inter Society Conference on Thermal Phenomenir For two heat pipes cyclopentane and hcfc123 obtained dT was: dt = dT[initial] + a(1- e ^ (-B*t)) where a (kelvin) and b (10^-3 / hours) are constants. For cyclopentane in their experiment they list a= 1.73 dt(initial) =1 B = 1.39 for a period up to 1500hrs (realively low amount of time) How this corresponds to computer heatsinks is unclear but the extrapolation shows that while they degrade over time they only degrade to a lower performance level not to infinity. |
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