Performance analysis of a high-temperature magnesium hydride reactor tank with a helical coil heat exchanger for thermal storage

Abstract Metal hydrides are regarded as one of the most attractive options for thermal energy storage (TES) materials for concentrated solar thermal applications. Improved thermal performance of such systems is vitally determined by the effectiveness of heat exchange between the metal hydride and the heat transfer fluid (HTF). This paper presents a numerical study supported by experimental validation on a magnesium hydride reactor fitted with a helical coil heat exchanger for enhanced thermal performance. The model incorporates hydrogen absorption kinetics of ball-milled magnesium hydride, with titanium boride and expanded natural graphite additives obtained by Sievert's apparatus measurements and considers thermal diffusion within the reactor to the heat transfer fluid for a realistic representation of its operation. A detailed parametric analysis is carried out, and the outcomes are discussed, examining the ramifications of hydrogen supply pressure and its flow rate. The study identifies that the enhancement of thermal conductivity in magnesium hydride has an insignificant impact on current reactor performance.