A comparative study on the performance and thermal behavior of an adiabatic compressed air energy storage system with packed-bed of different materials

Compressed air energy storage (CAES) technology offers an effective approach to mitigate the intermittency challenges associated with renewable energy grid integration. By integrating packed-bed thermal energy storage (PBTES) units, the adiabatic compressed air energy storage (A-CAES) system achieves efficient storage and utilization of the heat generated during compression. The study employs round trip efficiency (RTE) and thermal utilization efficiency as indicators to analyze of three configurations: single-stage sensible heat storage, single-stage phase change material (PCM) storage, and three-stage PCM storage. The influence of different thermal storage materials on system performance is also evaluated. Particular emphasis is placed on investigating the temperature evolution of the heat transfer fluid and the PCM within the PBTES unit, as well as the characteristics of the phase transition process. The results demonstrate that ⅰ) in the single-stage sensible heat storage configuration with a 13 m high PBTES, the RTE and thermal utilization efficiency of the A-CAES reached 73.97% and 81.85%, respectively; ⅱ) For the system with a single-stage PCM as the storage medium, the corresponding RTE and thermal utilization efficiency are 68.18% and 60.32%; ⅲ) For a multi-stage PCM configuration with PBTES height of 10 m, the RTE and thermal utilization efficiency are 68.34% and 69.13%. Compared to the sensible heat storage, the configuration resulted in reduction of 7.56% in RTE and 15.54% in thermal utilization efficiency, but achieved a 23.08% reduction in required PBTES volume. Furthermore, the utilization of PCMs can effectively stabilize the power output during the latter stage of the discharge phase.