Thermochemical energy storage (TCES) systems are a promising long-term storage solution for space heating applications due to their high energy density and low energy losses. Although identified as promising thermochemical materials, inorganic salt hydrates suffer from issues related to cycling stability, agglomeration, and deliquescence during charging and discharging. Using composites can help address these challenges by improving the material's structural stability and performance over multiple cycles. This study investigates a composite mixture of strontium bromide hexahydrate (SrBr2·6H2O) and silica gel (SiO2) in an open TCES system, experimentally and numerically. A two-dimensional numerical model for the SrBr2·6H2O/SiO2 composite mixture is developed and validated against in-house experimental data for charging and discharging processes. The effect of varying SiO2 abundance (0 %, 25 %, 50 %, 75 %, and 100 %) in the composite mixture on the charging and discharging performance of the system is studied. The study identified the 50 % SiO2 composite mixture as the optimal configuration, balancing structural stability provided by SiO2 and energy storage capacity rendered by SrBr2·6H2O. The pure SiO2 exhibits the highest energy supplied (360.29 kJ) and temperature rise, whereas the pure SrBr2·6H2O delivers the highest discharging efficiency (∼94.9 %). These findings provide valuable insights into optimised material composition for stable and sustainable energy storage. A multi-cycle simulation considering the 50 % SiO2 composite mixture prima facie demonstrates the operational stability of the open TCES over multiple cycles, warranting further experimental exploration under realistic conditions.
