Abstract:

This paper proposes a novel ejector-augmented adiabatic compressed air energy storage system for the large pressure loss of a conventional compressed air energy storage system in constant-pressure operation. Two-stage ejector is used to induce the exhaust gas after the work of the expander to recover part of the pressure energy loss and increase the inlet flow rate of the expander to improve the power generation capacity of the system. The thermodynamic model of the novel system is established, and its performance is compared with that of the conventional system under the same operating parameters. The effects of the primary fluid pressure, the second fluid pressure, and the intermediate pressure of the two-stage ejector on the system performance are investigated. When the primary fluid pressure, the second fluid pressure, and the intermediate pressure are increased, the research results demonstrate that the full-cycle efficiency of the system shows an approximate parabolic trend. Furthermore, an optimal operating parameter for the ejector is obtained. Under optimal working conditions, the system full-cycle efficiency is 63.32%, an improvement of 0.91 % compared to the 62.41 % cycle efficiency of the conventional throttling down method. Based on the above study, this paper provides a theoretical basis for the ejection efficiency of the compressed air energy storage system to reduce the throttling loss and improve its performance.

Key words: Compressed air energy storage, Two-stage ejector, Constant pressure operation, Cycle efficiency