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A comment on Airbus pioneers a superconducting powertrain cooled by liquid hydrogen. Parent comment

Re:Airbus pioneers a superconducting powertrain cooled by li... by XorNot on Wednesday April 21, 2021 @09:31AM (#26889426)
Motors are solid 3D structures. The more power you put in not superconducting, the more heat you have to extract. Superconductors mean you only need to keep your refrigerant cool, and that's a product of insulation effectiveness, not power output.
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Re:Airbus pioneers a superconducting powertrain cooled by li... by ethbr0 on Wednesday April 21, 2021 @09:51AM (#26889666)
This is the difference between electric and combustion powertrains, no?

In electric, heat is the enemy and inefficient.

In combustion, heat is a key component of the thermodynamic efficiency, unavoidable, and effectively only limited by material tolerances.

(I didn't major in physics, so someone keep me honest on the ceiling / floor efficiency equations for combustion engines?)

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Re:Airbus pioneers a superconducting powertrain cooled by li... by XorNot on Wednesday April 21, 2021 @10:22AM (#26890059)
You still have to cool a combustion engine - hence why car's have radiators.

Combustion engine's are also limited by Carnot cycle engine efficiency - about 64% theoretically, no more then 50% in the real world. So you're still going to wind up having to dump progressively more heat from a fixed surface area.

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Re:Airbus pioneers a superconducting powertrain cooled by li... by ethbr0 on Wednesday April 21, 2021 @10:55AM (#26890470)
(Post coffee) Cars have radiators to cool the operating structure (e.g. engine block), but that cooling's ancillary to power produced, no?

Carnot cycle was what I was grasping for.

Original point being that in a thermal engine, increasing your temperature gradient by increasing your high-temperature side (while holding exhaust constant) leads to more potential power.

Or IOW, a thermal engine that doesn't burn hot somewhere isn't going to produce much power.

(Electric being a completely different ball of wax)

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