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Vapour chamber with heatpipes much better than heatpipes only? - Page 5

post #41 of 61
Quote:
Originally Posted by psyclum View Post

the more heat required for a phase change(heat of vaporization) the more heat the gas(steam) carries with it when it does become a gas. it's one of the main reason why water is a good liquid for phase change. it's actually a good thing to have very high heat of vaporization because the amount of heat that is required for the vaporization is the amount it will carry with it once it becomes a gas and free to flow to the cooler part of the pipe. it's like the difference between using a spoon to dig a hole in the ground vs using a shovel. yes you can move faster with a spoon, but you can dig alot faster with a shovel.
besides, for liquids with lower heat of vaporization, it may not even reach the heat source before being boiled off and the heat source remain hot.

The increased area along with the use of water is the issue. In a small area the water might be an acceptable choice but not with larger areas where other refrigerants would work better because less heat is required for the phase change so the gas can transfer the heat to the fins..
post #42 of 61
Quote:
Originally Posted by AMD4ME View Post

The increased area along with the use of water is the issue. In a small area the water might be an acceptable choice but not with larger areas where other refrigerants would work better because less heat is required for the phase change so the gas can transfer the heat to the fins..

the speed limitation of a heat pipe system is the speed that the wick is able to return the liquid back to the heat source. it's a balance of how quickly liquid can be returned to the heat source via capillary action. capillary action is fueled by surface tension. the higher the surface tension the better the capillary action works. water happens to also have a very high surface tension which make it return to the heat source quicker then liquid of lower surface tension. so, in essence, water carries more heat with it when it is vaporized due to high heat of vaporization, and it can return to the heat source as a liquid faster then others due to surface tension. it also has a very high heat capacity so the total amount of water that's needed to be in the system is reduced compared to other liquids.
post #43 of 61
Thread Starter 
I have to say that theorical part is very different to practical part
Look at Some heatsink like 212+/evo which has HDT but have more temps than a CPU Cooler w/o HDT
post #44 of 61

I once saw a study of just that -- orientation of heatpipes. It turns out that orientation makes no difference. YMMV with cheap heatpipes that have less wicking. Have you noticed that at least one heatsink manufacturer advertises its extra wicking?

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alpha updated
(19 items)
 
secundus
(14 items)
 
 
CPUMotherboardGraphicsRAM
i7 4790k Gigabyte GA-Z97X Gaming-7 Intel HD4600 Crucial Ballistix Sport Very Low Profile 8GB Ki... 
Hard DriveCoolingOSMonitor
Samsung 840 EVO 500GB Prolimatech Megahalems Rev. C Windows 8.1 Home Premium 64-bit Acer K242HL 
KeyboardPowerCaseMouse
Dell SK-8110 (PS/2) Seasonic X460 Fanless motherboard tray from CM ATCS 840 Logitech MX 1100 
Mouse PadAudio
Dell Creative SoundBlaster X-Fi MB3 
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MonitorKeyboardPowerCase
Dell E207WFP 20-inch flat panel Logitech Wireless 510 Seasonic X-650 fully modular 80+ Gold Lian Li PC-7FN 
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post #45 of 61
Thread Starter 
wicking?? in which sense?
post #46 of 61
I'm not saying this is a definitive test or it's even scientifically accurate, but here is some interesting reading regarding a worst case scenario in poor heatpipe orientation.
post #47 of 61
here is another study by one of our OCN members on the effect of heatpipe orientation
post #48 of 61
Quote:
Originally Posted by psyclum View Post

the speed limitation of a heat pipe system is the speed that the wick is able to return the liquid back to the heat source. it's a balance of how quickly liquid can be returned to the heat source via capillary action. capillary action is fueled by surface tension. the higher the surface tension the better the capillary action works. water happens to also have a very high surface tension which make it return to the heat source quicker then liquid of lower surface tension. so, in essence, water carries more heat with it when it is vaporized due to high heat of vaporization, and it can return to the heat source as a liquid faster then others due to surface tension. it also has a very high heat capacity so the total amount of water that's needed to be in the system is reduced compared to other liquids.

As I posted early on, proper scientific testing will tell how this unit/concept performs compared to others. We can debate the pros and cons all day long but it won't tell us how this unit performs.
post #49 of 61
agreed. however this discussion does add to the general knowledge pool of the readers here. as long as we do not provide false information, it's still a good discussion.
post #50 of 61
Quote:
Originally Posted by PontiacGTX View Post

wicking?? in which sense?

wicking: meaning the substrate or method used to transport the liquidised vapor back to the origin of the heat to be boiled again.

Here's a link that explains more.

There are three main types.

Metal Sintered
Grooved
Metal Mesh (felt)
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