News Hydrogel Coated Heatsinks Significantly Boost Passive CPU Cooling Capabilities

mikewinddale

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It would thus work particularly well in the tropics . . . where relative humidity can be 80–90%.

Presumably, only for outdoor fixtures like cell towers? I would expect that any indoor location would have a dehumidifier to reduce the humidity to around 40 to 50 percent right? At 80 to 90 percent humidity, I would expect the interior walls to be covered in mold.
 
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Udyr

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Presumably, only for outdoor fixtures like cell towers? I would expect that any indoor location would have a dehumidifier to reduce the humidity to around 40 to 50 percent right? At 80 to 90 percent humidity, I would expect the interior walls to be covered in mold.
Not at all. Some tropical locations usually build with cinder blocks and concrete, and apply an initial paint coat to the finished structure before applying the final decorative layer. Even structures made of other materials are treated to prevent the excessive humidity from seeping through and create mold or rust.

What the article fails to mention or consider is the salinity levels present in said locations, which would probably affect the longevity of the material.
 
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For those wondering this works exactly like heat pipes and vapour chambers except it is using water in the air and on the external surfaces. The amount of heat energy to effect a phase change (latent heat) of a substance is FAAAAR greater than to simply heat up a substance without phase change (sensible heat). This is the basis for all phase change cooling whether in be passive such as this and vapour chambers, or active, such as that window shaker AC unit you rely on to keep that janky gaming rig from heating up your room. Cool stuff for sure but as noted in TFA it works best in bursty loads.
 
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terabite

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Presumably, only for outdoor fixtures like cell towers? I would expect that any indoor location would have a dehumidifier to reduce the humidity to around 40 to 50 percent right? At 80 to 90 percent humidity, I would expect the interior walls to be covered in mold.
i don't know where you live, but here in Argentina, humidity above 80% is an everyday thing, and there are no issues with it. We regularly get 100%, and the highest AVERAGE year-round humidity is 77% in Mar del Plata, yet it doesn't mean you'll get mold on your walls
 

hannibal

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So vaporizing moisture reduce the heat...
It works as long as there is moisture to vaporize. Cheaper to pour water to heatsink via water spray gun.
Heh!

The long time viability is what I am concerned. When the moisture has vaporized, what does that counting do to heat levels. Just pure physic.
 

bit_user

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For those wondering this works exactly like heat pipes and vapour chambers except it is using water in the air and on the external surfaces.
Yup. This is simply good ol' fashioned evaporative cooling.

The unique twist is that the hydrogel provides a unique substrate for it, in that it provides an easy way to evenly distribute the moisture over a large area and can be recharged simply through exposure to humid air.

as noted in TFA it works best in bursty loads.
One might imagine a cooling system consisting of multiple heatsinks that are alternated between, with one active while others are "recharging". In that way, it could be made usable for continuous loads. However, the size and complexity of such a solution might not be a net win over a conventional "dry" cooling system.
 

bit_user

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Cheaper to pour water to heatsink via water spray gun.
But, it seems tricky to evenly coat a heatsink with moisture. Especially one with a significant amount of surface area. Perhaps hydrogels could help with this? They don't have to get their moisture from the air. The paper mentions this method of recharging it, BTW.

When the moisture has vaporized, what does that counting do to heat levels.
I think you're asking if the hydrogel would become a thermal insulator, once dry? The paper mentions using a layer of 0.5 to 1.0 mm thick, but I don't see anywhere that they specify the heat flux of this specific thickness, when dry.