A Spin Seebeck Waste-Heat Generator with a Torsion-Coupled Spin Current Stage

The device examined here is a spin Seebeck generator intended for recovering low-grade industrial waste heat as auxiliary direct-current power. Its operating principle is that a temperature gradient across a ferrimagnetic insulator drives a magnon spin current, which a platinum layer converts to charge voltage by the inverse spin Hall effect, with the torsion coupling setting the spin-current ceiling used in the sizing. The design is computed from stated assumptions throughout; it is simulated, not measured, and no prototype results are reported. The headline result is a maximum electrical power of 41.5 mW, obtained with heat throughput of 36 W with a computed efficiency or performance coefficient of 0.115 per cent where that measure applies, for a unit of mass 2.4 kg whose characteristic scale is a hot-side temperature of 420 K. A parameter sweep reported in the Results section shows how the output moves when the principal variable is changed, and the density of the working material, 7.8e+03 kg per cubic metre, sits about 54.1 orders of magnitude below the neutron-carrier density bound of 9.72e+57 kg per cubic metre, so the bound enters this design as a sizing ceiling and a margin statement rather than as an operating condition. The limitations are stated plainly: the conversion coefficient is small, so useful power requires many elements in series and a large, well-maintained temperature difference; magnon transport degrades if the interface is contaminated. Status: SIMULATED, NOT MEASURED.