Numerical investigation of energy desorption from magnesium nickel hydride based thermal energy storage system

The use of dual metal hydride system for thermal energy storage consists of high and low-temperature metal hydrides. In this study, a 3D cylindrical Magnesium Nickel hydride bed is analyzed for thermal energy discharge. The energy discharge from metal hydride bed initially at temperature of 400 K, a heat transfer fluid at 500 K temperature is supplied to extract the heat generated due to exothermic chemical reaction. In this article, variation of the number of heat transfer fluid tubes and effect of variation of aspect ratio (ratio of diameter to height) on energy desorption and heat transfer from metal hydride bed is performed. The optimal number of heat transfer fluid tubes is determined for various aspect ratios. The temperature variation of the metal hydride bed with an increase in the number of heat transfer fluid tubes is analyzed. The study of aspect ratio variation on energy desorption and heat transfer characteristics is analyzed for three aspect ratios 0.5, 1, and 2. The variation of thermal energy desorbed, net heat transfer and temperature variation of metal hydride bed are analyzed. The adequate number of heat transfer fluid tubes for AR 0.5, 1, and 2 is identified as 32, 48, and 72, respectively. The cumulative heat released from MH bed with AR 0.5, 1, and 2 is 350.94 kJ, 330.56 kJ, and 310.42 kJ, respectively. The study will be useful in designing the optimized metal hydride bed reactor for thermal energy storage applications.