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Google's Liquid Cooling

(chipsandcheese.com)
399 points giuliomagnifico | 1 comments | | HN request time: 0.208s | source
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michaelt ◴[] No.45017512[source]
> TPU chips are hooked up in series in the loop, which naturally means some chips will get hotter liquid that has already passed other chips in the loop. Cooling capacity is budgeted based on the requirements of the last chip in each loop.

Of course, it's worth noting that if you've got four chips, each putting out 250W of power, and a pump pushing 1 litres of water per minute through them, water at the outlet must be 14°C hotter than water at the inlet, because of the specific heat capacity of water. That's true whether the water flows through the chips in series, or in parallel.

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foota ◴[] No.45017544[source]
Hm... but in the case when the chips are in serial, the heat transfer from the last chip will be less than when the chips are in parallel, because the rate of heating is proportional to the difference in temperature, and the water starts at a lower temperature for the parallel case for this last theoretical chip.
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1. fraserphysics ◴[] No.45017827[source]
One way to characterize the cost of cooling is entropy production. As you say, cooling is proportional to difference in temperature. However, entropy production is also proportional to temperature difference. It's not my field, but it looks like an interesting challenge to optimize competing objectives.