2025

Al-Maliki Wisam Abed Kattea; Alobaid Falah; Horst Maria Gabriela; Epple Bernd

A thermal energy storage system (TES) is investigated in this work. To charge the storage tank, hot air is passed through the fixed bed from top to bottom. In this process, the hot air transfers its thermal energy to the particles in the bed. The discharging process is carried out with cold air, which flows through the fixed bed in the opposite direction. A novel automated dynamic simulation model of the thermal energy storage system was created using the APROS simulation software. The developed model was validated with the measurements from the literature. This work is the first of its kind to operate with a heat transfer fluid (HTF) temperature of up to 1200 °C during the charging process. During discharge mode, the temperature of the HTF can be regulated using a bypass controller. The simulations were performed to investigate the behaviour of the fixed-bed storage system during charging/discharging cycles. For this purpose, 64 simulations with different parameters were carried out. In addition to the air, CO2 was used to improve the performance because its density is higher than air. The parametric study displays that cases 14 (A14 and C14) and cases 30 (A30 and C30) produce the best results for both alumina and ceramic when air is used as a heat transfer fluid for the examined parameters. According to the parametric analysis, case C14 used air as the HTF and reached a maximum thermal capacity of 3.237 MWh and utilization of 55.4%. Thereafter, the model is run using CO2 as a heat transfer fluid according to the parameters implemented in C14. A comparison between C14 (with air) and C14 (with CO2) was performed. The findings revealed a rise in thermal capacity and utilization of 4.5 % using CO2 as a heat transfer fluid compared to using air, and reduced compressor work, highlighting its advantages for enhanced efficiency.