Design and Advanced Dynamic Process Simulation with Experimental Validation for Sensible Thermal Energy-Storage Systems

A thermal-energy-storage (TES) system is investigated in this work. The charging process uses hot air passed through a fixed bed, transferring thermal energy to solid particles, while discharging occurs with cold air flowing in the opposite direction. A novel automated dynamic simulation model of the TES is developed and validated using data from the literature. This study uniquely operates with a heat-transfer-fluid (HTF) temperature of up to 1200 °C during charging, with discharge temperatures regulated via a bypass controller. Simulations explore the fixed-bed storage behaviour during charging/discharging cycles, with 64 parameter variations tested. In addition to air, CO₂ is evaluated as an HTF to enhance performance due to its higher density. Results show that Case C14 (using air) achieves a maximum thermal capacity of 3.237 MWh and utilization of 55.4%. When CO₂ is substituted for air under the same parameters, a thermal capacity and utilization increase of 4.5% is observed, along with reduced compressor work, highlighting CO₂'s advantages for improved efficiency.