储能压力对液态压缩空气储能系统特性的影响

In order to explore the intrinsic affecting mechanism of operating parameters of liquid air energy storage system (LAES) on the system performance and the method for improving system energy efficiency, a thermodynamic model of the system was established, and the process simulation was carried out using Aspen Plus software. The thermodynamic characteristics of the system were analyzed, and the influences of the energy storage pressure in liquid air tank on other units and the energy efficiency of the system were studied. The results show that high-grade compression heat and low recycling air flow rate can effectively improve the efficiency of compression heat reuse and system performance. As the energy storage pressure is increased from 0.86 MPa to 1.67 MPa, the grade of compression heat is improved, the reheating temperature between stages of expanders is increased from 114℃ to 160℃, and the recycling air flow is effectively reduced by about 0.5%. As a result, the power consumption of compressors is reduced, the total power output of expanders is increased, and thus the system efficiency is raised from 31.61% to 42.54%. Besides, the increase of energy storage pressure is helpful to reduce the heat leakage of cryogenic storage tank and the liquid mass fraction at the exit of cryo-turbine, which can further improve the comprehensive performance of the system.