A Thermal Energy Harvester Using LaFeSi Magnetocaloric Materials

A thermomagnetic generator (TMG) using a Halbach structure as a field source and a first-order LaFeSi magnetocaloric material (MCM) from Vacuumschmelze as the active substance is presented. The MCM, suspended on a cantilever beam, self-oscillates between a hot source and a heat sink. The mechanical energy associated with the oscillation is harvested and converted into electricity using the piezoelectric materials. This system is working between an 18 degrees C cold end and a 56 degrees C heat source (i.e., over a temperature difference between the reservoirs Delta T-res = 38 degrees C) and shows a power of 0.12 mu W (6.8 mu W per 1 cm(3) of MCM). We present and discuss a detailed analysis of the thermodynamic cycle underpinning the device mechanism, relying on the direct measurements on the working prototype and on a full laboratory characterization of the MCM. Although our system shows a state-of-the-art power output, our analysis gives useful clues toward further performance improvements.

Automated summary

A thermomagnetic generator using a Halbach structure and LaFeSi magnetocaloric material is presented, showing low power output but providing useful clues for performance improvements through detailed analysis and experimentation.