On 08/19/2016 12:10 PM, Stu Midgley wrote:
I think direct contact liquid cooling (DCLC)solutions from Asetek
and CoolIT are much more practical, as are immersion cooling
systems using 3M Novec engineered fluid. Novec is really appealing
because of the heat transfer efficiency of the change of state. I
believe it was originally designed as an electronic parts cleaner,
too. It evaporates at room temp like other electronic cleaners, so
when you pull hardware out the liquid, it's dry in a matter of
seconds, and very clean, too! Much more practical than mineral oil
in that regard. 3M claims it has a very low global warming factor,
too.
Personally, I think DCLC since any leaks in the data center should
be smaller than if a tank-like chassis springs a leak, and there
one is scared of the environmental impact of water, even when
antifreeze and other water treatment chemicals are added to it, as
would be needed in this use case.
2 phase solutions are sexy but ultimately impractical.
* what happens when your recondensing loop fails? and you've
evaporated all the fluid off...
I agree that's a problem, but some failures can be mitigated with
redundancy, like redundant circulating pumps or including the pumps on
UPS and having proper failsafes incorporated into the cooling system.
* try and get a permit to hold large volumes of it in a computer room
* try and find a computer room that will allow it in
* the above two are mostly due to the low boiling point of the fluid
I understand that. That's why they are usually closed systems. I would
like to point out at SC, several booths had open tanks of the stuff on
the exhibitors floor. I believe IBM says it's safe, but I wouldn't want
to take my chances breathing it in every day.
* expensive (~ an order of magnitude)
AND you don't actually need a 2 phase solution to get the heat off the
cpu's etc. A single phase solution works just fine.
That's true, which is why water DCLC is a viable option, as well as some
other thermally conductive liquids that don't rely on boiling (besides
mineral oil), too, BUT multiphase cooling is much more efficient in
terms of absorbing/releasing energy.
--
Dr Stuart Midgley
sdm...@sdm900.com <mailto:sdm...@sdm900.com>
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