Ca-montmorillonite clay as thermal energy storage material

Ca-montmorillonite clay (Ca-M), is one of the materials, which can perform reversible direct hydration/dehydration process. The feasibility of using Ca-M as a thermal energy storage material was investigated. The adsorption isotherms, differential thermal analysis (DTA) and infrared (IR) spectroscopy data were studied. The adsorptive capacity of Ca-M was calculated and expressed as the maximum amount of water adsorbed on certain amount of clay. The results showed a reasonable adsorptive capacity for Ca-M, which amounted to 0.31 g H2O/g of dry clay, as pre-hydration temperature reached 250°C. The energy storage capacity was calculated as a function of the net adsorbed amount of water on the clay surface. The maximum heat storage capacity obtained for dry clay was 487 cal/g. Thus, Ca-M can be considered as an efficient energy storage material compared to the other materials used.