[Beowulf] More about those underwater data centers
pbisbal at pppl.gov
Tue Nov 6 08:16:58 PST 2018
> . And serviceability is challenging. You need to pull the "wet" boards
> out, or you need to connect and disconnect fluid connectors, etc. If
> you're in an environment where you can manage that (or are forced into
> it by necessity), then you can do it.
I think everyone on this list already knows I'm no fan of mineral oil
immersion (It just seems to messy to me. Sorry, Stu), but immersion
cooling with other liquids, such as 3M Novec engineered fluid addresses
a lot of your concerns. It as a low boiling point, not much above room
temperature, and it was originally meant to be an electronic parts
cleaner (according to a 3M rep at the 3M booth at SC a few years ago, so
if you pull a component out of it, it dries very quickly and should be
The low boiling point is an excellent feature for heat transfer, too,
since it boils from the heat of the processor (ebullient cooling). This
change of state absorbs a lot of energy, making it very effective at
transferring heat away from the processor. The vapor can then rise and
condense on a heat exchanger with a chilled water heat exchanger, where
it again transfers a lot of heat through a change of state.
On 11/05/2018 06:30 PM, Stu Midgley wrote:
> I refute both these claims.
> You DO want to run your boards immersed in coolant. It works
> wonderfully well, is easy to live with, servicing is easy... and saves
> you almost 1/2 your power bill.
> People are scared of immersion cooling, but it isn't that difficult to
> live with. Some things are harder but other things are way easier.
> In total, it balances out.
> Also, given the greater reliability of components you get, you do less
> If you haven't lived with it, you really have no idea what you are
> Serviceability is NOT challenging.
> You really do NOT want to run boards immersed in coolant - yeah,
> there's folks doing it at HPC scale
> Whatever the coolant, it leaks, it oozes, it gets places you don't
> want it to go. And serviceability is challenging. You need to pull
> the "wet" boards out, or you need to connect and disconnect fluid
> connectors, etc. If you're in an environment where you can manage
> that (or are forced into it by necessity), then you can do it.
> Dr Stuart Midgley
> sdm900 at gmail.com <mailto:sdm900 at gmail.com>
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