Numerical and experimental investigations on a regenerative static thermomagnetic generator for low-grade thermal energy recovery

Harvesting low-grade thermal energy from waste heat and natural resources is an extremely promising method to partially substitute depleting fossil fuels. As one of the alternative technologies, static thermomagnetic power generation is subjected to inefficiency due to the non-regenerative power cycle. To give an insight to what degree can current technology realize regeneration and guide the direction of future research on thermomagnetic power generation, a regenerative static thermomagnetic generator was designed, modeled, constructed, and tested for the first time in this study, several parameters were systematically optimized as well. Firstly, the working principle of the studied static thermomagnetic generator and the importance of regeneration was reviewed. Then both numerical and experimental methods were used to evaluate the dependence of power output and load voltage on mean temperature, temperature difference, working frequency, and load resistance. Numerical simulation indicated that the actual regenerative effect can improve the thermal efficiency of the static thermomagnetic generator by a factor of 1 at a frequency of 0.2 Hz. In experiments, a maximum electric power of 25 nW was extracted from the static thermomagnetic generator at a frequency of 0.4 Hz. Significant discrepancies between the numerical and experimental results have been identified and explained in detail. This work also shows that the performance of the actual regenerative cycle is far from that of an ideal regenerative cycle.