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What would be the Specific Impulse of a steam-based propulsion system like this model in space?

Are there any types of engine that works this way?

Could 2 tanks be designed to rotate slowly in space creating micro gravity in the tanks. The tank facing the sun would boil the water to the other condensing tank to cause the water to move a turbine similar to the sand moving past the neck of an hour glass?

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Both tanks condense and boil depending on the orientation to the Sun. A sun synchronous orbit would be optimal.

Gravity or rotation may not be needed if the tanks are placed on the opposite sides of the spacecraft or satellite in non sun synchronous orbits.

Can a satellite utilize gravity gradient stabilization, solar power, electrodynamic tethering and dynamic quadrupole momentum at once?

peterh
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Muze
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    Still there is intuition and creativity in this question, which may not be answered by googling it. Addressing water phase changing energy density and water refueling in space issues could be some kind of an answer, without other people to do an engineering evaluation. – user721108 Mar 26 '19 at 00:17
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    Actually some interesting options here, using https://en.wikipedia.org/wiki/Stirling_engine but possibly the better question is 'can a heat engine out perform solar cells for space energy generation'. Suspect no but possible case if making in situ (making pipes vs solar cells from local materials. For this particular setup thermal inertia of the tankage will make it very heavy per unit energy produced, and have dead periods during the rotation. – GremlinWranger Mar 26 '19 at 02:49
  • @GremlinWranger yes that was my thought on how to convert more sunlight to electricity. – Muze Mar 26 '19 at 02:50
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    I think this is an interesting question. You wouldn't want the rotation speed to be too fast because you want basically all the fluid in the tank in the sun to boil off. – zeta-band Mar 27 '19 at 20:10
  • A temperature of -280F sounds cold, but is almost useless if there's nowhere for the heat to go. What mechanism is going to remove the heat at the "cold" side? If you don't understand what I'm asking, think about how a vacuum flask works. A vacuum makes an incredibly good insulator. – Ray Butterworth Mar 30 '19 at 01:18
  • @RayButterworth good point and extra surface area would be needed. – Muze Mar 30 '19 at 01:20
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    The title and the body of the question do not match. Please pay attention. – Antzi Apr 04 '19 at 06:21
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    Specific impulse has nothing to do with your question; since your system does not have any propellant. Please try to understand the terms you attempt to use in your question. – Antzi Apr 04 '19 at 06:23
  • What's your metric for efficiency ? Power to weight ? Power to complexity ? Volume to power ? Surface area to power ? – Antzi Apr 04 '19 at 06:27
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    As mentioned by Antzi isp should not be used to describe your idea, since there is no thrust generated. On the other hand, converting heat difference to generate power has already been researched, mostly with free piston stirling engines and Seebeck generator. – user721108 Apr 04 '19 at 07:44
  • @GremlinWranger my engine has no piston but it does use an impeller.so is it a Stirling engine? – Muze Apr 04 '19 at 22:50
  • Stirling engines use pistons to extract energy, rather than a turbine. This allows them to work across very small differentials. Turbines will need a much larger pressure/flow rate and ask much more of the bearings and seals for continued function https://en.wikipedia.org/wiki/Core_lock. – GremlinWranger Apr 04 '19 at 22:59

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