[Beowulf] A/C to water cooling, considering the transition

Josip Loncaric josip at lanl.gov
Thu Apr 14 13:21:48 PDT 2005

David Mathog wrote:
> Or is chilled water  too cold for direct use in cooling
> computer equipment?  (For nstance, causing condensation
> problems.)

I'm not sure that you'd be using pure chilled water to cool your CPUs 
directly.  Apple's liquid cooled Mac uses some kind of alcohol, I think.

Since air cooling dominates today, there are also transitional 
technologies to consider.  A mixed air/water cooling scenario involves a 
water-cooled rear door to cool the hot air coming out of a rack; this 
doesn't cause condensation if that the liquid is not too cold.

See http://www.designnews.com/article/CA500772.html for an example: 
Altix systems can dissipate ~8KW per rack, so they use a water cooled 
rear door, which works with chilled liquid of just under 60 deg. F. 
Just in case any condensation happens anyway, they added a drain feature 
to the rack.

Given the rapid increases in packaging density (e.g. blade servers with 
power densities much higher than SGI's Altix), I'm pretty sure that 
large computer installations will want liquid cooling.  Making this 
transition is a challenge today, but within a few years, more plumbing 
will be needed in high end computer rooms.


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