耦合有机朗肯循环的液化空气储能系统性能研究

Study on Performance of LAES Coupled with Organic Rankine Cycle

为解决液化空气储能系统(LAES)压缩热利用不完全的问题,构建了耦合有机朗肯循环的液化空气储能系统(ORC-LAES)。对ORC-LAES系统建立热力学性能计算模型,在设计参数下分析压缩机出口压力、膨胀机入口压力、加压水初温、加压水流量比及膨胀机级数对ORC-LAES系统性能的影响。结果表明,当压缩机出口压力由6 MPa上升到16 MPa、加压水初温从293 K上升到323 K时,系统的循环效率、火用效率和液化率均下降;当膨胀机入口压力由8 MPa上升到18 MPa时,系统循环效率和火用效率均增加;当加压水流量比由0.51上升到0.96时,系统循环效率和火用效率先增加再减少,流量比为0.71时,系统的循环效率和火用效率达到最大;在压缩热利用上耦合有机朗肯循环要优于增加膨胀机级数;ORC-LAES系统与LAES系统相比,循环效率提高4.8%,火用效率提升5.1%。

To solve the problem of incomplete utilization of compressed heat in liquefied air energy storage system(LAES),a LAES system coupled with organic Rankine cycle(ORC-LAES) was constructed.Thermodynamic performance calculation model for ORC-LAES system was established, and the influence of compressor outlet pressure, expander inlet pressure, initial temperature of pressurized water, pressurized water flow ratio and expander stage number on ORC-LAES system performance was analyzed under design parameters.The results show that when the outlet pressure of the compressor rises from 6 MPa to 16 MPa and the initial temperature of pressurized water rises from 293 K to 323 K,the cycle efficiency, exergetic efficiency and liquefaction rate of the system decrease;when the inlet pressure of the expander rises from 8 MPa to 18 MPa, the system cycle efficiency and exergetic efficiency increase;when the flow ratio of pressurized water increases from 0.51 to 0.96,the cycle efficiency and exergetic efficiency of the system first increase and then decrease, and when the flow ratio is 0.71,the cycle efficiency and exergetic efficiency of the system reach the maximum value;coupling ORC is better than increasing the number of expander stages in the utilization of compression heat;compared with the LAES system, the ORC-LAES system has a 4.8% increase in cycle efficiency and a 5.1% increase in exergetic efficiency.