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I've been wondering, what would be a scientific approach to cooling a handheld device that generates power by using an internal heat source, by the means of things like Stirling engines and/or the Seebeck effect?

Of course one could use some form of radiator with a cooling fan, but I wanted one that would work as well in vacuum as it would inside an atmosphere... So, are there good ways of quickly dispersing heat or using it for work that would work in a closed system?

Also, is there maybe a way of forcing the heat away into a direction even if against the thermal gradient, as to force the cold part of the generators cool quicker?

Edit: Adding more information to the question.

So, the device I'm thinking of would be a science-based plasma weapon, like a plasma saber or plasma gun, I'm not too concerned about the weapon itself, but more on it's battery/generator, which would use a constant source of heat, like a radioisotope to generate energy, and it would keep generating energy constantly.

Because of that, I was thinking of ways to keep this battery having high internal temperatures for good power generation, but still cold to the touch outside, and that it could run underwater, on an atmosphere or in space without overheating and maybe melting down and leaking radiation on the people around.

It's for a RPG, so I wanted to get details and the scientific approach so players can get creative with it

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  • $\begingroup$ "Is there maybe a way of forcing the heat away into a direction even if against the thermal gradient": refrigerators and air conditioners do it... (And you may have noticed that they need a source of power to work. Heat won't go against a temperature gradient without being actively pumped, just as water won't go uphill.) (And you may want to clarify what you mean by "dispersing heat in a closed system".) $\endgroup$
    – AlexP
    Dec 4, 2021 at 18:02
  • $\begingroup$ Oh, yeah, you're right, but I sort of mean, sort of like, a heat laser or something, the device in question would be for a plasma weapon of sorts, so using the heat from the energy generation to heat plasma a bit further would be good, though it can't be the primary form of heat dispersal because the device would overheat and maybe explode if left alone for too long $\endgroup$ Dec 4, 2021 at 18:08
  • $\begingroup$ Maybe you want dissipation and dissipating instead of dispersion and dispersing, but only you can tell. $\endgroup$
    – AlexP
    Dec 4, 2021 at 18:13
  • $\begingroup$ "Using the heat from the energy generation to heat plasma a bit further": for sure the cold end of the thermal engine ought to be much cooler than plasma, no? (Or if it is hotter than plasma, just how hot is the hot end of the engine?) $\endgroup$
    – AlexP
    Dec 4, 2021 at 18:15
  • $\begingroup$ Yes, it's supposed to be touchable at least, but it would be cool if the heat that was supposed to be dispersed on the cold end to be send to the plasma on the weapon output instead $\endgroup$ Dec 4, 2021 at 18:33

2 Answers 2

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Also, is there maybe a way of forcing the heat away into a direction even if against the thermal gradient, as to force the cold part of the generators cool quicker?

definitely not.

there are no other options than a radiator if you don't want to expel stuff. the larger the radiator the better it works. eventually you would need to use heat-pipes to transport it from your device to the end of the radiator. but that is all you can do.

there is a difference in the design of your radiator between the one in the atmosphere and the one in vacuum. those in a vacuum are a single fin/sheet. whereas those in the atmosphere can be made more compact with more fins without much of a efficiency drop.

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Compressed gas.

fog

source

I saw one of these in action recently. Pretty slick. Compressed gas heats up when you compress it. Then later on when you let the gas out and it expands, entropy pays you back by sucking up some heat.

That is how you cool your weapon: a tank of compressed gas. Bonus - it makes clouds of mist that are then illuminated by your plasma weapon firing. Which will make for awesome anime visuals.

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  • $\begingroup$ Cool, but sort of impratical, because the weapon would have seemingly limitless energy source, but limited by the ammount of gas you can carry on it... And since the energy keeps being generated, it keeps consuming gas without even being used =O I mean, it could have a closed system that uses gas, like a refrigerator, sure, but I'm concerned with the part of it that dissipates heat, and if it expends gas to do so, it would unnecessarily limit it's operation $\endgroup$ Dec 4, 2021 at 19:23
  • $\begingroup$ @MiguelVieira - you get it. Limitations on a weapon make it more interesting for a fiction. My raygun has infinite shots but it gets hot. I carry a bandolier of compressed N2O canisters to keep it cool. If I am pressed it might get really hot before I can get a new canister on there. $\endgroup$
    – Willk
    Dec 4, 2021 at 20:06
  • $\begingroup$ I do get that limitations are great for fiction, but I was thinking on battery charge and time for recharging instead of fuel/resource limitations, like gas or ammo $\endgroup$ Dec 4, 2021 at 20:11
  • $\begingroup$ @MiguelVieira - you are right that battery life is more realistic if it is that kind of fiction. But even for a créatif it is hard to turn charging a battery into gripping drama. This answer is presented in the spirit of making engaging fiction enjoyed by the sort of people who dig plasma weapons (which are themselves wildly impractical for a realistic world). $\endgroup$
    – Willk
    Dec 4, 2021 at 20:22

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