Power generation by a thermomagnetic engine by hybrid operation of an electromagnetic generator and a triboelectric nanogenerator

Abstract

Summary This paper reports a thermomagnetic generator based on the magneto‐caloric effect of Gadolinium to scavenge low‐grade thermal energy and its eventual conversion into electrical energy. Gadolinium is one of the distinct materials whose Curie temperature is nearly room temperature. For this reason, a Gadolinium‐based thermomagnetic engine offers enormous possibilities to harness available waste heat from the industries. In this work, the performance of an electromagnetic generator (EMG) coupled with a triboelectric nanogenerator (TENG) was experimentally investigated as it is driven by a thermomagnetic engine exploiting low temperature waste heat. At the temperature difference of 46.5°C between the hot and cold water jets, the thermomagnetic engine produced an average rotational speed of 263 ± 1.5% rpm and a mechanical output power of 76.38 ± 0.5% mW. At the aforementioned rotational speed, the hybrid generator delivered a rectified peak voltage of 15.34 V on an open‐circuit, a short‐circuit current of 20.1 mA, and the largest power output, 12.1 mW, at a 120 Ω load. It was demonstrated that the proposed energy harvester could light dozens of light‐emitting diodes or power a digital thermometer. It is feasible that the proposed thermomagnetic generator can be utilized as an effective power source for various applications.

Optimization of a cylindrical thermomagnetic engine for power generation from low‐temperature heat sources

“…The thermal efficiency of the fabricated TME was calculated to be 0.104%. The efficiency of the TME was much higher than that of recently designed rotating TMEs 17,18 . The engine can be effectively applied whenever waste heat and room temperature water are available around us.…”

“…The efficiency of the TME was much higher than that of recently designed rotating TMEs. 17,18 The engine can be effectively applied whenever waste heat and room temperature water are available around us. In a commercial context, the TME can provide a promising energy solution to harvest trillions of joules of waste heat (between 45 C and 65 C) from various industries.…”

“…16 The prototype generated an oscillation frequency of 0.33 Hz, a power density of 0.2 W/kg, and work output of 0.6 J/kg/cycle under a temperature difference between a hot-and cold-side of 60 K. A low-grade energy-harvesting device was proposed using two different generators; one was an electromagnetic generator, and the other one was a nanogenerator. 17,18 To fabricate the TME, 16 gadolinium blocks, one permanent magnet, and three water inlets (two hot and one cold) were used. For commercial applications, a TME needs an optimized model that will help to reduce the fabrication costs and produce the maximum output.…”

“…An efficient thermomagnetic energy harvester was demonstrated using gadolinium to scavenge low‐grade thermal energy 16 . The prototype generated an oscillation frequency of 0.33 Hz, a power density of 0.2 W/kg, and work output of 0.6 J/kg/cycle under a temperature difference between a hot‐ and cold‐side of 60 K. A low‐grade energy‐harvesting device was proposed using two different generators; one was an electromagnetic generator, and the other one was a nanogenerator 17,18 . To fabricate the TME, 16 gadolinium blocks, one permanent magnet, and three water inlets (two hot and one cold) were used.…”

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

“…Therefore, the research of TMG based on a few MCE materials, such as Gd, (Mn,Fe) 2 (P,As), NiMn‐based Heusler alloys, and MM′X (M, M′ = transition metals, X = carbon or boron group elements) compounds, starts to attract a surge of interest in very recent years. [ 17–36 ] However, except the benchmark Gd, most of these materials undergo a first‐order phase transition that inevitably accompanies with distinct thermal hysteresis. Large thermal hysteresis would cause the discrepancy of working temperatures during the heating and cooling cycles, which is undesirable for the practical application.…”