Thermomagnetic Generation Performance of Gd and La(Fe, Si)₁₃H_y/In Material for Low‐Grade Waste Heat Recovery

Abstract

The recovery of waste heat is urgently required to solve challenging energy and environmental issues. Thermomagnetic generation (TMG) technology using magnetic phase transition materials can realize the conversion of low‐grade waste heat into electrical energy. However, efficient TMG materials hold the key to the development of this technology. Herein, the TMG performance of La(Fe, Si)13Hy/In is studied in comparison with the benchmark material Gd systematically. The induced current I is related to the change rate of the average magnetization over time dM/dt according to Faraday's law. In addition, the location of TC in the working temperature range is an important factor affecting TMG performance. Due to the sharper magnetic transition, La(Fe, Si)13Hy/In presents a maximum intrinsic I of 9.12 µA g−1, ≈90% higher than that of Gd (4.82 µA g−1). Moreover, the average output electrical power density and cost performance of La(Fe, Si)13Hy/In are 0.42 mW m−3 and 0.102 nW USD−1, which are also significantly higher than those of Gd, 0.10 mW m−3 and 0.005 nW USD−1, respectively. In comparison with Gd, the present work suggests that the La(Fe, Si)13Hy/In possesses much higher potential in the field of low‐grade waste heat recovery.

High-performance thermomagnetic generator controlled by a magnetocaloric switch

“…In this context, we use finite element simulation to investigate the effect of key structural parameters on the magnetic circuit performance, and then fabricated a TMG device based on the optimized parameters. The experimental results demonstrate that this TMG exhibits a much higher performance than previous TMGs; 11 , 12 , 16 , 17 , 21 , 22 the max power density is 2 to 3 orders of magnitude higher than those of previous reports 12 , 17 , 21 . It also exhibits higher power density in comparison with TEG 23 – 26 and PEG 5 , 27 , 28 technologies.…”

“…In the 19th century, Edison 9 and Tesla 10 proposed the concept of the thermomagnetic generator (TMG), which could convert heat into electricity based on the Faraday’s law of electromagnetic induction. In principle, the TMG performance mainly relies on the temperature-driven phase transition of the thermomagnetic material (TMM) and the associated large change in magnetization around the Curie temperature ( T C ) 11 , 12 . Theoretical studies show that the conversion efficiency of TMG could reach as high as 55% of the Carnot efficiency 13 .…”

“…Nevertheless, the output power of the passive TMG is low due to the high impedance of PEM and TEM as well as due to the energy loss during indirect conversion 11 , 16 . On the contrary, active TMG exhibits higher theoretical conversion efficiency than passive TMG since it utilizes the magnetization change of TMM to directly convert thermal energy into electrical energy 12 – 14 , 17 – 19 . Unfortunately, the practical performance of the previous active TMGs is low due to the limited magnetic flux change in the magnetic circuit 12 , 17 , 19 .…”

“…On the contrary, active TMG exhibits higher theoretical conversion efficiency than passive TMG since it utilizes the magnetization change of TMM to directly convert thermal energy into electrical energy 12 – 14 , 17 – 19 . Unfortunately, the practical performance of the previous active TMGs is low due to the limited magnetic flux change in the magnetic circuit 12 , 17 , 19 . The optimization of the magnetic circuit structure was lacking.…”

Origin and avoidance of double peaks in the induced voltage of a thermomagnetic generator for harvesting low-grade waste heat

“…The performance of a thermomagnetic system is strongly determined by the thermomagnetic material used [8,15] and many more materials have been suggested recently [16][17][18]. While most material libraries are based on literature values of material properties, only a few direct experimental analyses of thermomagnetic materials are available [19]. For the particular TMG used here, we recently published a comparison between La-Fe-Co-Si and Gd [20].…”