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This video shows a demonstration of what is claimed to be Dr. Johnson's Heat Engine. I'm not sure that a Dr Johnson was responsible for it but it's available commercially in toy form.

It uses the shape-memory property of nitinol to convert a temperature difference into work.

My question is, if we cranked the wheels, could we use it in reverse to generate a temperature difference? If not, why not?

chasly - supports Monica
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  • I haven't watched the video in detail, but it appears it involves the same principle as in this post: https://physics.stackexchange.com/questions/522124/a-heat-engine-based-on-rubber-bands/522131#522131 that involves work produced by the expansion and contraction of rubber bands due to temperature difference. – Bob D Jan 08 '21 at 14:13
  • Bob D - That looks similar however it relies on gravity as well as heat to make the wheel 'topple'. The one I'm asking about just needs a heat differential. Gravity is convenient to hold the liquids in situ but it doesn't provide the motive power. – chasly - supports Monica Jan 08 '21 at 14:26
  • Like I said, I didn't watch the video in detail and that it only appeared to involve the same principle. – Bob D Jan 08 '21 at 14:37
  • @Bob D - No worries. I think it would take much longer for me to describe the machine than for someone to watch the video, so let's you and I call it quits. – chasly - supports Monica Jan 08 '21 at 14:45

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