Thermodynamic analysis of thermochemical energy storage system based on AB5 type hydride pairs

Abstract

The present study deals with the performance analysis of thermochemical energy storage system based on four different working pairs, namely LaNi4.85Sn0.15-MmNi4.6Al0.4, LaNi4.75Sn0.25-MmNi4.6Al0.4, LaNi4.65Sn0.35-MmNi4.6Al0.4 and LaNi4.55Sn0.45-MmNi4.6Al0.4. The first law and second law performance parameters are considered to evaluate the performance of the energy storage system. The temperature of heat storage and heat recovery for the four different working pairs are in the range of 93–140 °C and 105–165 °C respectively. Recovering the heat at higher temperature than that of storage is called heat upgradation. Highest degree of heat upgradation is 24 °C, and it is obtained for the working pair of LaNi4.55Sn0.45-MmNi4.6Al0.4. The theoretical highest energy storage density and COP are 129 kJ/kg and 0.54 respectively for the working pair of LaNi4.65Sn0.35-MmNi4.6Al0.4. From the second analysis, the lowest exergy loss and highest second law efficiency are 2.57 kJ and 96.4% respectively for the working pair of LaNi4.75Sn0.25-MmNi4.6Al0.4. Based on the first law analysis, the working pair, LaNi4.65Sn0.35-MmNi4.6Al0.4, is taken as best pair and based on the second law analysis, the working pair, LaNi4.75Sn0.25-MmNi4.6Al0.4, is taken as best pair. However, suitable working pair need to be selected based on the type of application.