[Beowulf] 96 cores in silent and small enclosure

Lux, Jim (337C) james.p.lux at jpl.nasa.gov
Wed Apr 7 12:22:35 PDT 2010

If you put something  hot into a liquid, you have to worry about forming a film of vapor that keeps the liquid from touching the hot thing, and radically reduces the heat transfer.  It's all tied up with the turbulence in the liquid, the surface tension of the liquid, etc.

Boiling is a really good way to move heat: the heat of vaporization is huge, for a small temperature change, compared to just the liquid's specific heat.  But, it's more complex to design.  It's used in very high power solid state electronics and in high power vacuum tubes, as well.  The key is that the boiling point of the liquid has to be close to the desired operating temperature of the parts being cooled.  Various Freons work well.

Look up Leidenfrost effect (why LN2 droplets skitter around, or water on a hot pancake griddle)..
It's also related to why you can walk across burning coals in bare feet. (the true test of belief in Physics)

James Lux, P.E.
Task Manager, SOMD Software Defined Radios
Flight Communications Systems Section
Jet Propulsion Laboratory
4800 Oak Grove Drive, Mail Stop 161-213
Pasadena, CA, 91109
+1(818)354-2075 phone
+1(818)393-6875 fax
From: Jonathan Aquilina [mailto:eagles051387 at gmail.com]
Sent: Wednesday, April 07, 2010 7:59 AM
To: Lux, Jim (337C)
Cc: Hearns, John; beowulf at beowulf.org
Subject: Re: [Beowulf] 96 cores in silent and small enclosure

filming in what sense with the heat though i thought that the heat would prevent the oil from congealing?

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