A thermal energy harvester using LaFeSi magnetocaloric materials

Smail Ahmim (1) , Morgan Almanza (1) , Vincent Loyau (1) , Alexandre Pasko (1) , Frédéric Mazaleyrat (1) , Martino Lobue (1)

1 SATIE - Systèmes et Applications des Technologies de l'Information et de l'Energie

A thermomagnetic generator (TMG) using an Halbach structure as a field source and a first order LaFeSi magnetocaloric material (MCM) from Vacuumschmelze as 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 piezoelectric materials. This system is working between a 18°C cold end, and a 56°C heat source (i.e. over a temperature difference between reservoirs ∆Tres = 38°C) and shows a power of 0.12µW (6.8 µW per 1 cm 3 of MCM). We present and discuss a detailed analysis of the thermodynamic cycle underpinning the device mechanism, relying on 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 towards further performance improvements.

Mots clés: thermal engine; magnetocaloric materials; pyromagnetic effect; energy harvesting; thermodynamics

Domaines: Electromagnétisme

Smail Ahmim, Morgan Almanza, Vincent Loyau, Alexandre Pasko, Frédéric Mazaleyrat, et al.. A thermal energy harvester using LaFeSi magnetocaloric materials. IEEE Transactions on Magnetics, 2021, ⟨10.1109/TMAG.2020.3008753⟩. ⟨hal-02925562⟩