[time-nuts] OT question about liquid cooling

J. Forster jfor at quikus.com
Thu Oct 4 00:53:12 UTC 2012


And the heat transfer to the fluid s better too. However, boiling has it's
own serious issues.

-John

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


> If you let the water boil, it takes even (much) less.
>
> Tom
>
> ----- Original Message -----
> From: "J. Forster" <jfor at quikus.com>
> To: "Discussion of precise time and frequency measurement"
> <time-nuts at febo.com>
> Sent: Wednesday, October 03, 2012 8:14 PM
> Subject: Re: [time-nuts] OT question about liquid cooling
>
>
> 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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>
>
>
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