IBM Supercomputer Cooled With Hot Water

1sockchuck writes "IBM has deployed an innovative supercomputer cooled by hot water in a Zurich computer lab. The Aquasar supercomputer employs a chip-level liquid cooling system that can use water at temperatures as high as 60 degrees C (140 degrees F), and as a result consumes up to 40 percent less energy than a comparable system using room-level air-cooling. The system also uses waste heat to provide warmth to buildings, reducing Aquasar's carbon footprint even further."

Comments

Saw a presentation on this last year...

[Saint Aardvark]

I was at LISA '09, and Dr. Bruno Michel (works for IBM, mentioned in the article) made a presentation on this work (or at least very, very similar work). You can see the presentation, or download the MP3, here:

http://www.usenix.org/event/lisa09/tech/tech.html#michel

Interesting talk, and well worth your time.

Re:Sooo

[bsDaemon]

a soupercomputer?

Re:There is a video

[jd]

Hot water doesn't freeze faster. However, water at 80'C will cool to 60'C much faster than water at 60'C will cool to 40'C, given standard atmospheric temperature and pressure for the ambient temperature of the room. The flow of heat from a hot medium to a cooler medium varies non-linearly with temperature. For example, as you approach the same temperature, the flow of heat approaches zero.

(In other words, if they piped through cold water which was heated to room temperature, a passive radiator would be useless.)

There is a drawback with hot water, though. The temperature gradient issue cuts both ways. As the temperature of the water approaches the temperature of the chips, the heat flow from the chips is reduced. Thus, water at 60'C will not draw off as much heat as water at 40'C, if the chips were to run at 80'C. You've got to balance this sort of approach fairly carefully.

I rather like the Cooling Tower approach (evaporative passive cooling). Basically, you blast the water through a nozzle that turns it into a fine mist. You collect the water that actually reaches the reservoir at the bottom and top it off. The drawback of this method is that it is somewhat bulkier than a radiator system. It is also not a closed system and therefore is a bit more expensive to run. On the other hand, evaporative cooling is much more effective than relying on simple heat flows, so you can get away with a lower temperature gradient at the cooling end. This, in turn, means you get a steeper temperature gradient for the chips, which means they're cooled much more effectively and can therefore be driven much harder without loss of reliability.