Proof-of-Concept Static Thermomagnetic Generator Experimental Device

Abstract

A thermomagnetic power conversion device is constructed using water flows with very low caloric energy. The device has two active regenerators built from (Mn,Fe) 2 (P,As) materials suspended in a magnetic circuit as proposed by Brillouin and Iskenderian. The final magnetic circuit design was further optimized with finite-element simulations. The permanent magnet acting as field source was 1.4 kg of NdFeB alloy. The active part of the generator consists of 48 disks of (Mn,Fe) 2 (P,As) material with four different Curie temperatures of 300 K, 304 K, 307 K, and 310 K (27°C, 31°C, 34°C, and 37°C) measured in 1 T. Into each plate, microchannels are laser cut. By stacking these plates in series, two regenerators with a gradient temperature span are built. Both generators have an exact weight of 26.9 g. The material was cycled at different speeds to find the maximum power output at the optimum frequency. Critical to a better design is a more tapered design and different materials. The tapered design ensures a greater external field and a larger external field change across the material. The materials for devices that use water as heat-transfer fluid in combination with this type of regenerator design should have a lower latent heat while maintaining their magnetic properties. This will increase the cycling speed and improve the power output of this type of device.

Caloric effects in ferroic materials

“…Though conceived by Tesla 26 and Edison 27 more than 100 years ago, working demonstrators became feasible only with advanced magnetocaloric materials. 28,29 These exhibit a sharp change in magnetization with temperature, potentially allowing for harvesting low-grade waste heat commonly available below 100°C. First demonstrations of such devices work also on a miniaturized scale 30 and, with a similar approach called a thermomagnetic motor, also within the kilowatt range.…”

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

“…Christiaanse and Brück proposed a static thermomagnetic generator that consists of 48 discs of (Mn,Fe) 2 (P,As) materials with four different Curie temperatures of 27°C, 31°C, 34°C, and 37°C and obtained improved cycling speed and power output. Ujihara and Carman conducted experiments on an efficient thermomagnetic energy harvester for a small‐level application using piezoelectric materials.…”

Structural, magnetic and magnetocaloric properties of (Mn, Co)2(Si, P) compounds

“…On the other hand, the recent surge of interest for MCE materials has also brought back into light other applications, like the Tesla thermomagnetic generators [17]. Some tests in a prototype using the MnFe(P,As) giant MCE materials have recently been carried out [18]. On top of some technical difficulties which explain part of the modest experimental output of the generator, simulations indicate that giant MCE materials were not the most suitable choice of working material.…”