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ESA turbo-inductor turbine heater

Posted: Apr 10, 2017 2:34 am
by Asteroza
Not sure how interesting this is to the folks here but... ... S-NTER.pdf

The european space agency did some work on trying to "supercharge" a nuclear thermal rocket, trying to move beyond a simple inductive heater wrapped around the supersonic portion of the rocket nozzle to heat/accelerate the hydrogen propellant.

The bright spark they had is what they call a turbo-inductor. The basic concept is a turbine direct drive heater, using generator rotor magnets embedded in the tips of a helium loop turbine, which cause ohmic heating in a tungsten heater fin assembly wrapped beyond the turbine tips. They basically use the massive cold sink of LH2 to work with a helium brayton cycle and a nuclear heat source to superheat the hydrogen propellant after it passes through the reactor, allowing the heat to exceed the materials limits of the reactor itself for the downstream subsonic flow.

End up with a nice and compact "electric" heater that is directly driven by the turbine with no intermediary electronics or power conversion systems. Design-wise, they thought they could get the hydrogen propellant hot enough to accidentally melt the tungsten heater section (suggesting the later turbine stages directly inductively heat the hydrogen rather than through the tungsten intermediary heater fins).

I can't imagine many cases where you need to turn mechanical work into heat in a compact manner. The only obvious idea that came to mind was something like NACC-FIRES where you needed to heat air after the nuclear HX before putting into the FIRES container, but a FIRES resistance brick setup sounds much more controllable and cheaper than a turbine mounted heater that you can't easily turn off. I suppose if you wanted to avoid a recuperator or something like that...

Re: ESA turbo-inductor turbine heater

Posted: Jul 15, 2018 8:45 pm
by Asteroza
I stand somewhat corrected. You can use a turboinductor as a process heat superheater of sorts.

John Bucknell proposed at the TEAC08 conference using a turboinductor running off secondary coolant loop helium in a split stream, using some of the helium to drive a turboinductor to superheat the remaining helium for process heat delivery. ... txdi2/view

His design is at a somewhat handwavy light conceptual level (specing a single fluid MSR?) with rough numbers. Endgame is apparently some better economics balancing between direct electric load and coproduct production via process heat. With everything downstream running off the helium secondary, switching between helium turbogenerators and hot helium to process heat applications (notably hydrogen/synfuel production) though it looks using some CO2 tertiary loops as well as S-I hydrogen production via desalinated water produced from final heat rejection.