Liquid Cooling for Smartphones/SOCs


vcoleiro1

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I saw this interesting article today of how Microsoft has been using liquid cooling in some of their smartphones. Not saying Pyra could use it, but I thought I'd post it out of interest.


http://www.techtree.com/content/features/9956/why-microsoft-uses-liquid-cooling-lumia-950.html
http://www.fujitsu.com/global/about/resources/news/press-releases/2015/0312-01.html


11-1c_tcm100-1559499.jpg
 
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vcoleiro1's image shows something that contains many of the parts of a refrigerator or freezer, the only thing missing from the setup that's currently in your kitchen is a pump. It's not liquid cooling, as liquid cooling uses a pump, and also doesn't rely on phase change. It's also not a heat pipe, as that also doesn't use phase change, and only works to tend to equalise the temperate at its two ends. The article claims they're using a cleverly etched copper panel over the chip that uses the heat to effectively vaporise the liquid, and then only as vapour to pass into the vapour line.

I also wonder what the hell they're using as their refrigerant (for want of a better word). Something that is liquid at room temperature but will vaporise at a few dozen degrees higher.

On the other hand it might just be a disguised heat pipe.
 
vcoleiro1's image shows something that contains many of the parts of a refrigerator or freezer, the only thing missing from the setup that's currently in your kitchen is a pump. It's not liquid cooling, as liquid cooling uses a pump, and also doesn't rely on phase change. It's also not a heat pipe, as that also doesn't use phase change, and only works to tend to equalise the temperate at its two ends. The article claims they're using a cleverly etched copper panel over the chip that uses the heat to effectively vaporise the liquid, and then only as vapour to pass into the vapour line.
Huh? Evaporation/condensation is exactly what makes a heat pipe efficient at conducting heat:
https://en.wikipedia.org/wiki/Heat_pipe

I also wonder what the hell they're using as their refrigerant (for want of a better word). Something that is liquid at room temperature but will vaporise at a few dozen degrees higher.
What matters is that the system contains the working fluid at both its liquid and vapour forms at the working temperature. Consider a closed container partially filled with water, remove the air, water vapour fills that empty space.

On the other hand it might just be a disguised heat pipe.
I'm sure it's exactly that. Only that they made it into a loop rather than a pipe, probably increases efficiency. Even on a heat pipe there's fluid circulation while it is operating.
 
As far as I can tell, Freon is a brand name for a number of coolants, mainly CFCs and HCFCs, most of which have now been banned. But looking at wikipedia's list of refrigerants, there are still a few other molecules with chip-friendly boiling points of 40-60 degrees celcius, and perhaps one of the forumulations of Fluorinert is the answer (perfluorohexane).

Edit: Oops, you're quite right about heat pipes, Yoyobuae. I thought they were just dumb conductors, but it seems I was making an untested assumption.
 
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