Date: Thu, 22 Jun 2000 20:30:33 +0200 (EET) From: Narvi <narvi@haldjas.folklore.ee> To: Olaf Hoyer <ohoyer@fbwi.fh-wilhelmshaven.de> Cc: Brian Handy <handy@isass0.solar.isas.ac.jp>, freebsd-hardware@FreeBSD.ORG Subject: Re: Hardware in space? Message-ID: <Pine.BSF.3.96.1000622201532.2206V-100000@haldjas.folklore.ee> In-Reply-To: <4.1.20000622120110.00a62a70@mail.rz.fh-wilhelmshaven.de>
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On Thu, 22 Jun 2000, Olaf Hoyer wrote:
> >> Well, the question is:
> >> Which parts _do_ need cooling?
> >
> >All that generate more heat than can be radiated away?
> Hi!
>
> Well, yes, thats obvious. I meant, what parts are that? (list of)
>
Processor. Possibly also chipset and DRAM, depending on the parts and
speeds. Luckily, the figures should be in datasheets that also tend to be
downloadable from the manufacturers in pdf these days.0
> >
> >10 watts is still a lot.
> Yes, but this is figured for full system load, so actual operation will be
> less.
>
The various 486 clones should produce quite a bit less heat. Also,
industrial variant of the processor buys you 10C of ... well, time. Also,
it may be possible to have the processor doze - or even halt at times it
is not doing something usefull. Yes, I know the halt trick is standard in
FreeBSD.
> >
> >But if it is absolutely neccessary that it worked and made no errors, this
> >no longer holds.
> Yes, agreed. In cases where ultimate reliability is needed, you cannot
> play. But seeing that also some homebuilt gear was used, one should give it
> a try (and test it before launching it)
>
>
> >
> >> Basically, you need to transport the heat=energy away from the chip.
> >> On earth, you may take air as transport and dissolver.
> >> But why no liquid cooling?
> >
> >Crazy! Liquid weights a lot - and besides, how do you cool the liquid?
> Only a small amount of.
> No cooling for that liquid.
> We know the wattage the CPU has to get rid of. We know the time the CPU is
> running.
No, we don't. Read the part about the assembled and ready for launch but
standing-by part.
> So we can calculate the amount of energy that needs to go into that liquid.
> The heat capacity (sorry, did not look up the english term for it) of water
I'd be suprised if they called it differently. Anyways, the energy in
{your choise of unit} that goes to rise the temp of a substance by 1
degree.
> or other things is well-known. So when we allow the water to get 20 degrees
> warmer, we know which amount of water(in milliliters) one would need to
> take all the heat from the CPU, preventing it from going beyond the magical
> ~60 degrees centigrade.
>
Yes. It sorta works until they are inside the gravity well, and for one
time mission. Of course, the packaging of the liquid may have to be able
to not to break upon coming back to earth.
A big-big-big heatsink may still be better.
> I assume that this phase only goes for about 15 minutes.
>
> Regards
> Olaf Hoyer
> --------
> Olaf Hoyer www.nightfire.de mailto:Olaf.Hoyer@nightfire.de
> FreeBSD- Turning PC's into workstations ICQ:22838075
>
> Liebe und Hass sind nicht blind, aber geblendet vom Feuer,
> dass sie selber mit sich tragen. (Nietzsche)
>
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