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| ▲ | fhars 16 hours ago | parent | next [-] |
| There are even commercially available prototypes of that vacuum cooling technology, if you want to perform your own experiments with that concept: https://www.amazon.com/Thermos-Stainless-Ounce-Drink-Bottle/... |
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| ▲ | ahartmetz 5 hours ago | parent | next [-] | | To be fair, they have mirror surfaces inside. A more realistic prototype would be ultra-black for something like 10-50x better radiative heat transfer. Of course it would still be more like shitty insulation than like good conduction. | |
| ▲ | sanex 16 hours ago | parent | prev | next [-] | | That's my water bottle. 10/10 would recommend for not passing temperature gradients. | |
| ▲ | RugnirViking 16 hours ago | parent | prev [-] | | this kind of sarcasm will go over their head. People truly don't understand vacuums | | |
| ▲ | ReptileMan 12 hours ago | parent [-] | | I absolutely don't understand how vacuum works. So I absolutely cannot model how a Dewar flask which has 15 billion light year thickness between the inner and outer wall - a wall that is very close to absolute zero will behave. |
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| ▲ | Ekaros 15 hours ago | parent | prev | next [-] |
| I wonder if there should be levels of "in theory". Yes theoretically black body radiation exist and well stuff cools down to near background radiation via that. But the next level is theoretical implementation. Like actually moving around the heat from source and so on. Maybe this could be the spherical cow step... Reminds me of the hyperloop. Well yes, things in vacuum tube go fast. Now does enough things go fast to make any sense... |
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| ▲ | salawat 14 hours ago | parent [-] | | >Now does enough things go fast to make any sense... You're worried about rates when we can't even get the ball rolling on safety for human occupancy, maintenance, workability. I swear, nothing on Earth more dangerous than someone with dollar signs in their eyes. |
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| ▲ | morshu9001 3 hours ago | parent | prev | next [-] |
| Passively yeah. Can't imagine it's anywhere near as fast as evap or chillers |
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| ▲ | dayjah 16 hours ago | parent | prev | next [-] |
| Serious question: how in theory? I’m under the impression you need to radiate through matter (air, water, physical materials, etc). Is my understanding of the theory just wrong? |
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| ▲ | LegionMammal978 16 hours ago | parent | next [-] | | Heat conduction requires a medium, but radiation works perfectly fine in a vacuum. Otherwise the Sun wouldn't be able to heat up the Earth. The problem for spacecraft is that you're limited by how much IR radiation is passively emitted from your heat sinks, you can't actively expel heat any faster. | |
| ▲ | estimator7292 6 hours ago | parent | prev | next [-] | | Hot objects emit infrared light no matter the conditions. The hotter the object, the more light it throws off. By radiating this light away, thermal energy is necessarily consumed and transformed into light. It's kind of wild actually | |
| ▲ | ethmarks 16 hours ago | parent | prev [-] | | There is some medium in low Earth orbit. Not all vacuums are created equal. However, LEO vacuum is still very, very sparse compared to the air and water we use for cooling systems. The main way that heat dissipates from space stations and satellites is through thermal radiation: https://en.wikipedia.org/wiki/Thermal_radiation. |
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| ▲ | Sharlin 16 hours ago | parent | prev | next [-] |
| Yes. And it's an absolutely terrible way to get rid of heat. Cooling in space is a major problem because the actually effective ways to do it are not available. |
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| ▲ | Avicebron 16 hours ago | parent | prev | next [-] |
| It's not the Sun..it's the lack of medium. |
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| ▲ | jhanschoo 15 hours ago | parent | prev | next [-] |
| You can radiate the excess energy away on the non-sun facing part on Earth almost just as well..., though corrosion is an issue. |
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| ▲ | ffsm8 13 hours ago | parent [-] | | "just as well"? I man you totally can radiate excess heat energy on earth, but your comment implies that the parents idea of radiating off excess "energy", specifically HEAT energy in space is possible, which it isn't. You can radiate excess energy for sure, but you'd first have to convert it away from heat energy into light or radio waves or similar. I don't think we even have that tech at this point in time, and neither do we have any concepts how this could be done in theory. | | |
| ▲ | ReptileMan 12 hours ago | parent [-] | | >specifically HEAT energy in space is possible, which it isn't. https://en.wikipedia.org/wiki/Black-body_radiation | | |
| ▲ | ffsm8 11 hours ago | parent [-] | | I see, yes. I was thinking more along the lines of radiating heat energy at a scale that's useable for cooling, not at the more extreme levels of over 500°C/1k fahrenheit That's technically correct I guess, at some temperature threshold it becomes possible to bleed some fractions of energy while the material is exceedingly hot. |
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| ▲ | ethmarks 16 hours ago | parent | prev [-] |
| There's no air and negligible thermal medium to convect heat away. The only way heat leaves is through convection from the extremely sparse atmosphere in low Earth orbit (less than a single atom per cubic millimeter) and through thermal radiation. Both of which are much, much slower than convection with water or air. Space stations need enormous radiator panels to dissipate the heat from the onboard computers and the body heat of a few humans. Cooling an entire data center would require utterly colossal radiator panels. |
