Characterization methodology of a magnetic heat exchanger for linear thermomagnetic motor

Thermomagnetic motors (TMM) offer a promising solution for converting low-grade thermal waste into usable power by exploiting the phase transition of magnetic materials, particularly near their Curie temperature, under varying thermal and magnetic field conditions. Recent developments in magnetic materials with Curie temperatures near room temperature have opened new avenues for TMM applications. However, the performance characteristics of these materials are often underexplored. This study presents a comprehensive experimental methodology for evaluating the heat transfer, force generation, and operational dynamics of TMMs. Using gadolinium (Gd) as the test material, due to its well-established thermomagnetic properties, the study examines the force variation as a function of temperature and position within the motor, as well as the temperature evolution over time for different cycle periods. The effect of fluid flow configuration was also assessed, showing that counterflow increases the temperature difference ( ΔT ) by 50 to 400% compared to parallel flow, depending on the cycle period. Additionally, for the same ΔT , the counterflow configuration reduces the half-cycle duration by up to 45%, thereby increasing the motor’s potential power output. These findings provide valuable insights into the optimization of TMM operation, highlighting the importance of fluid flow direction in enhancing thermal performance and power efficiency. Future work will focus on implementing these findings into simulation models to further optimize TMM designs and explore the use of different magnetic materials for enhanced performance.