Study Shows Coil Design Could Dramatically Improve Thermomagnetic Heat-to-Electricity Generators
Researchers have published an analytical and numerical model showing that coil size is a critical, previously overlooked factor in thermomagnetic generator (TMG) performance. TMGs convert waste heat to electricity via changes in material magnetization, but existing prototypes have not used optimally sized coils. The findings suggest that literature TMG prototypes could have generated 10 to 400 times more power simply by using larger coils.
A preprint posted to arXiv presents a coupled magnetic-electric circuit model for thermomagnetic generators (TMGs), devices that harvest waste heat by exploiting magnetization changes in solid materials to induce an electromotive force in a coil via Faraday's law. The study, led by Rasmus Bjørk, is the first to systematically investigate how coil design affects TMG output power. The central analytical finding is that TMG power scales linearly with coil volume, and this relationship holds regardless of the specific combination of wire radius and number of turns chosen. The model was validated against experimental data before being applied retrospectively to TMG prototypes reported in the scientific literature. The analysis revealed that those existing prototypes were significantly underperforming, with power outputs estimated to be 10 to 400 times lower than what optimally sized coils would have achieved. The work highlights a straightforward engineering lever — coil volume — that has been systematically neglected in TMG development to date.
What's missing
As a preprint, this work has not yet undergone formal peer review, so the model's assumptions and the experimental validation have not been independently scrutinized. The study does not address practical engineering constraints (e.g., weight, cost, or spatial limits) that may prevent simply scaling up coil size in real applications.
What different sources said
- arXiv physicsCenter
Coils in thermomagnetic harvesters -- a comparative study
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