Vermiculite/LiCl Composite for Adsorption Thermal Energy Storage

Abstract

Sorption based thermal energy storage systems are amassing more attention of the researchers, due to their high energy storage density, stability and cyclic performance. Several materials have been used for adsorption based thermal energy storage technology. One promising group of materials are hygroscopic salts (e.g. metal chlorides), due to their high energy storage density and water vapour sorption capacity. However, hygroscopic salts are difficult to handle due to deliquescence and issues of cyclic stability. One method of stabilizing hygroscopic salts is to impregnate a host material with them to form a salt-in-matrix composite. Vermiculite is considered to be a good candidate as a host material for salt-in-matrix composites for thermal energy storage due to its high porosity, high stability, and low cost. Pure vermiculite has low energy storage density in comparison to traditional adsorbents. However, when vermiculite is impregnated with LiCl energy storage density values of up to 159 kWh/m 3 can be achieved at 50% relative humidity after a regeneration temperature of 120°C. This paper includes the synthesis and characterization, e.g. structural and thermal energy storage properties of the vermiculite based composite.