[Beowulf] 'liquid cooled' racks

Jim Lux James.P.Lux at jpl.nasa.gov
Wed Dec 6 19:47:17 PST 2006

At 06:07 AM 12/6/2006, Richard Walsh wrote:
>Jim Lux wrote:
>>At 03:45 PM 12/5/2006, Richard Walsh wrote:
>>>Greg Lindahl wrote:
>>>>On Tue, Dec 05, 2006 at 12:11:07PM -0600, Richard Walsh wrote:
>>>>>One of the key innovations on the Cray X1 is that the circuits 
>>>>>are "on the ceiling"
>>>>>so to speak and sprayed from below.  The fluid is gravity 
>>>>>collected and cycled up again.
>>>>This technology predates the X1 by a while.
>>>    Mmm ... I did not know that ... in a reasonably successful 
>>> commercial product (i.e. an innovation, rather
>>>    than a mere invention)?   What was/is/were/are the product(s)?
>>>    Perhaps outside of HPC ...
>>This has been around for quite a while (decades at least).  It was 
>>in a Fluorinert brochure back in the mid 80s that I 
>>recall.  There's also versions with ebullient (boiling) 
>>cooling.  There might even be high power vacuum tubes cooled this 
>>way, although I think they either tend to use a cooling jacket or a 
>>boiler, as opposed to spraying).
>This is drifting away from the useful, but I was asking what other 
>successful HPC (or computing generally)
>product has used a spray-cool, gravity collection system the like 
>Cray X1.  I am not saying there isn't one, just
>asking someone to tell what it is.

How do you define "successful"?  Paying the salaries of the 
developers? Making a profit for the company using it? Working without breaking?

>And as a side note, to me innovation implies successful commercial 
>application ... I understand that evaporation
>is a cooling process ... ;-) ...

Lots of successful innovations aren't very commercially viable (in 
the sense of providing a return to the shareholders).  The Mars 
Rovers are fairly successful, contain lots of innovation, but there's 
not much commercial value in the science data returned from them.

There are "wick/evaporation" cooling systems around too.. some "heat 
pipes" work by this principle. In fact, most passive heat pipes work 
by some sort of phase change (evaporate where it's hot, condense 
where it's cool) scheme.


James Lux, P.E.
Spacecraft Radio Frequency Subsystems Group
Flight Communications Systems Section
Jet Propulsion Laboratory, Mail Stop 161-213
4800 Oak Grove Drive
Pasadena CA 91109
tel: (818)354-2075
fax: (818)393-6875 

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