Comparative energy and exergy analyses of pumice and vermiculite-based salt-in-matrix composites for low-grade thermochemical heat storage applications

Thermochemical heat storage (THS) is a promising technology for enhancing renewable energy utilisation, with thermochemical materials (TCMs) playing a pivotal role in THS performance. This study aims to experimentally evaluate the cyclic thermodynamic performance of nine different composite TCMs based on pumice and vermiculite. According to the results, V-LiCl achieved the highest four-cycle average energetic efficiency of 74%, followed by P-CaCl2-LiCl with 70%. Peak exergetic efficiency was obtained with V-LiCl at 17.5% in the first cycle, which gradually dropped to 5.5% in the fourth cycle. Based on the testing results, pumice-based TCMs showed more stable hygro-cyclic and exergetic efficiency.