Thermal parameter optimization design of an energy storage system with CO2 as working fluid

This paper presents a optimization design method on the compression ratio of the compression process and the expansion ratio of the expansion process for the compressed gas energy storage system using carbon dioxide as the working fluid. On this basis, from the thermal parameter perspective of the stage design, compression ratio/expansion ratio design, and compression heat temperature, the thermal characteristics are analyzed using round-trip efficiency and heat storage efficiency as measurement indicators, and a better design scheme for energy-saving and efficiency improvement is obtained. The results show that it will have a positive role in the improvement of the system performance with a three stage compression-three-stage expansion design structure, an un-equal compression ratio-equal expansion ratio design scheme, and a compression heat temperature of 388.15K. In addition, the round-trip efficiency is up to 74.07% and the heat storage efficiency is up to 51.95%, which has good thermal performance and energy-saving effect for the energy storage system. (c) 2021 Elsevier Ltd. All rights reserved.