[time-nuts] OT question about liquid cooling

J. Forster jfor at quikus.com
Wed Oct 3 20:14:08 EDT 2012


It actually takes supprisingly little water flow to dissipate 5 kW.

Very roughly 5 kW = 1250 cal/sec  (4.18 J/cal)

so, for a 1 C degree = 1.25 liters/sec

at 50C degrees = 25 mL / sec. = 1.5 L/min.

-John

======================


> BWIWY (back when I was young) we needed a dummy load for a supercomputer
> (think Cray YMP size) that drew many many kw.
>
> Our test load was about 250' of 3/4" copper tubing coiled at about 12" dia
> and 1" spacing. The load was varied by changing where the + and - leads
> were bolted onto the coil with u bolts.
>
> The whole mess was cooled by running water through it. A hose barb on the
> input connected up to the cold water supply and the output was run into a
> drain. You had too little resistance dialed in when all thy came out the
> output end was steam. :)
>
> Anyway such a test load could be replicated using 1/4" ice machine copper
> tubing available at the hardware store, some hose clamps, and or hose
> barbs.
>
> Bob
>
> On Oct 3, 2012, at 19:35, Tom Harris <celephicus at gmail.com> wrote:
>
>> My day job is large industrial power supplies. The test racks have large
>> resistive loads with big fans exhausting to the outside. Cheap & simple.
>> Safety is by several strings of temperature cutouts wired in series. We
>> usually get work experience students in to wire them up.
>>
>> Tip: to make a funny valued power resistor, just get the next value up
>> and
>> wrap some nichrome wire around it to bring it down to the correct value.
>>
>> I met an engineer who made a battery charger for one of our submarines.
>> This was tested by putting the load bank in a dumpmaster, and keeping it
>> filled up with water using a firehose!
>>
>> On 4 October 2012 02:01, Javier Herrero <jherrero at hvsistemas.es> wrote:
>>
>>> Hello all,
>>>
>>> Please excuse me for the OT, but since this list is plenty of very
>>> knowledgeable colleagues, I'm tempted to ask...
>>>
>>> I need to cool several resistive loads, in the order of 5kW, and I plan
>>> to
>>> use a cold plate and a liquid-to-liquid heat exchanger like the Lytron
>>> LCS-20, but this unit is quite big, and an overkill (it has 20kW
>>> capability).
>>>
>>> If someone could suggest me a smaller liquid-to-liquid heat exchanger,
>>> and
>>> preferably a rack mount unit (and share any experience), it would be
>>> most
>>> welcome.
>>>
>>> Since this has not too much to do with time and frequency, please
>>> answer
>>> off list.
>>>
>>> Thank you very much! Best regards,
>>>
>>> Javier
>>>
>>>
>>>
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>>
>>
>>
>> --
>>
>> Tom Harris <celephicus at gmail.com>
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