A Thermochemical Long‐Term Heat Storage System Based on a Salt/Zeolite Composite

Abstract For the purpose of a long‐term heat storage system based on water sorption, a composite material consisting of CaCl 2 and zeolite Ca‐X, obtained by ion exchange with Ca 2+ and subsequent impregnation with CaCl 2 of a binder‐free granulated zeolite Na‐X, was prepared on a technical scale. In a lab‐scale apparatus, the heat storage density of the composite material reaches values up to 260 kWh m −3 for water vapor partial pressures up to 33 mbar. As compared to the pure zeolites Ca‐X and Na‐X, this corresponds to an increase in heat storage density of 45 % and 68 %, respectively. An engineering concept based on the mechanical transport of the composite heat storage material through a prereactor and a main reactor was demonstrated in a hardware‐in‐the‐loop test bench.