Multiparametric evaluation of a magnetic field source for thermomagnetic generator

Thermomagnetic generators (TMGs) represent a promising solid-state technology for low-grade waste heat recovery. While extensive research has addressed working materials and heat transfer optimization, systematic analysis of magnetic field source design in TMGs remains underexplored. This study presents a parametric finite element analysis of the magnetic field source in a TMG. Magnetostatic and transient simulations were performed to evaluate the effects of permanent magnet (PM) material (neodymium-iron-boron [NdFeB], Alnico, and Ferrite), its dimensions, and air gap width, on the TMG output power and specific power. It is shown that reducing PM thickness yields a substantial gain in specific power output per PM mass, while an increased air gap can be maintained without significant effects on output power. The study also investigates Alnico PM as a sustainable, rare-earth-free alternative. These findings contribute to the development of mass-optimized and cost-effective thermomagnetic energy harvesters.