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Given that cryogenic fuel and oxidisers exist, I wonder if the reverse is workable.

Are there fuels or oxidisers that have been considered for rockets that must be kept hot to be usable? By hot I mean significantly above room temperature to reach either liquid or gaseous form, whatever needed for the engine.

Nathan Tuggy
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lijat
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    Opposite, as in not cryogenic, or opposite, as in much hotter than room temperature? – Nathan Tuggy Apr 12 '18 at 23:01
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    I am not familiar with the term thermogenic, and googling it mostly turns up references in the medical field. Can you clarify your question, perhaps giving some reason why you think such propellants might exist? Are you asking, perhaps, about propellants that would have to be kept warm for storage? – Organic Marble Apr 12 '18 at 23:31
  • There are concepts in other fields such as molten salt batteries that must be kept at an elevated temperature to function. Maybe they mean something like that. – Saiboogu Apr 13 '18 at 01:45
  • The intent is fuel that must be kept hotter than room temperature – lijat Apr 13 '18 at 06:01
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    From an impulse perspective added beryllium would make a nice fuel. 1560K melting point would make it pretty "thermogenic" I guess. So a rocket using LOX, LH2 and LBe would perform a lot better than even LOX/LH2 (5295 m/s vs 4462 m/s acc. Wikipedia). Note that while cryogenics boil off, thermogenics would freeze which probably keeps them from being practical. – Christoph Apr 13 '18 at 06:50
  • -1Production of very low temperatures, or "cryogenesis" is a fairly recent development near the end of the 19th century. Merriam-Webster says the first known use of the word "cryogenic" was in 1896, when the generation of very low temperatures, or "cryogenesis” was becoming a "hot topic". Cryogenic does not refer to a particular temperature so much as it does the fact that you need a refrigerator to generate such a low temperature. So your attempt to use "thermogenic" in this context is not really correct or helpful. – uhoh Apr 13 '18 at 08:17
  • I think if you rewrote your question sticking to standard, accepted use of terminology, it would basically be "Are there any situations where hot rather than cold propellants might be advantageous?" You could then propose things like phase changes (to liquid or gas), enhanced kinetics (reaction rates), or even ionization as possible examples. – uhoh Apr 13 '18 at 08:18
  • I you want to use a much cheaper fuel than rocket petrol RP1, bunker fuel oil may be used like many big (sea) ships. But this fuel has a lot of disadvantages, it is dirty, contains to much sulfur, must be heated to be liquid in tanks and needs to be heated again for injection. It would be a waste of money to use the cheapest fuel. If the cooling channels of the rocket engines are blocked by fuel residues, the engine may be lost and likely the whole rocket and its payload. – Uwe Apr 13 '18 at 12:33
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    +1 good job on the rewrite! There are already four votes to re-open, almost there! – uhoh Apr 16 '18 at 03:41
  • Do you understand why certain propellants/oxidizers are kept cool to begin with? Answering that would give you more insight into answering this question? – Paul Apr 22 '18 at 19:24
  • @Paul if you mean that they are cooled to a liquid phase to fit more in the tanks without huge preasures and still allow the fuel and oxidiser to mix and react then yes. If there is more to it please enlight me. – lijat Apr 22 '18 at 20:21
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    @Paul I was mainly thinking of using elrments or compounds that are solid at room temperature as fuels. If we could use gaseous carbon and liquid oxygen in an engine that would be very helpfull for in sitiu resource utilization on mars for example. – lijat Apr 22 '18 at 20:24

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