Date: Thu, 22 Jun 2000 12:08:16 +0200 From: Olaf Hoyer <ohoyer@fbwi.fh-wilhelmshaven.de> To: Narvi <narvi@haldjas.folklore.ee> Cc: Brian Handy <handy@isass0.solar.isas.ac.jp>, freebsd-hardware@FreeBSD.ORG Subject: Re: Hardware in space? Message-ID: <4.1.20000622120110.00a62a70@mail.rz.fh-wilhelmshaven.de> In-Reply-To: <Pine.BSF.3.96.1000622113850.2206U-100000@haldjas.folklore. ee> References: <4.1.20000622075529.00979b80@mail.rz.fh-wilhelmshaven.de>
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>> 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) > Most parts of a notebook are designed to run quite cool, also due to lower >> power consumption. > >Yes - but there is air present that takes heat away. In space there isn't. > >> Also a Flash disk also runs quite cool, no need for extra cooling. >> The only source of heat I can imagine would be the CPU. >> (At least of the computer used therefore) >> >> So using some low-power version like a 486 or an IDT C6/Winchip will help >> decreasing emitted heat. >> >> I ran a Winchip C6 (old one) at 50x2 = 100 MHz in a desktop system without >> even a heatsink (yes, bare CPU, no heatsink or fan) for some weeks under >> load, no probs. >> The Winchip only consumes half of the power than a similar (MHz) Intel >> Pentium MMX or AMD K6. >> (At 200 MHz, the IDT eats 10 Watts, Intel/AMD ~20 Watts) >> > >10 watts is still a lot. Yes, but this is figured for full system load, so actual operation will be less. >> In my experience, if the system is intended to run only for some minutes, >> the CPU even at full pace hasn't enough time to overheat. >> Even if you need cooling, there's another idea. >> > >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. 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 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. 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) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message
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