Energy Storage Science and Technology ›› 2021, Vol. 10 ›› Issue (5): 1824-1834.doi: 10.19799/j.cnki.2095-4239.2021.0348

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Exergy destruction characteristics of a supercritical carbon-dioxide energy storage system

Lexuan LI1,2(), Yujie XU1,2,3, Zhao YIN1,2,3, Huan GUO1,2,3, Xianrong ZHANG1,4, Haisheng CHEN1,2,3(), Xuezhi ZHOU3()   

  1. 1.Institute of Engineering Thermophysics, Chinese Academy of Science, Beijing 100190, China
    2.University of Chinese Academy of Sciences, Beijing 100049, China
    3.National Energy Large Scale Physical Energy Storage Technologies R&D Center of Bijie High-tech Industrial Development Zone, Bijie 551712, Guizhou, China
    4.School of Energy Power and Mechanical Engineering, Beijing 102206, China
  • Received:2021-07-15 Revised:2021-08-04 Online:2021-09-05 Published:2021-09-08

Abstract:

Energy storage is an important technology to realize the large-scale utilization of renewable energy sources; however, the supercritical compressed carbon dioxide energy storage (SC-CCES) system has advantages of compact equipment, high efficiency and security, and it is one of the most promising large-scale energy storage technologies. The models of conventional and advanced exergy analysis of SC-CCES are established in order to the investigate exergy destruction in each process and component of the system, and its causes are revealed. The characteristics of avoidable/unavoidable and endogenous/exogenous exergy destruction, correlations among different processes and components are determined. The simulation results show that the system efficiency is 60.30%. Considering the components, compressors exhibit the largest exergy destruction, accounting for 33.85% of the total exergy destruction, followed by the expander, throttle valve, cooler, recuperator, mixer and heater. For advanced exergy analysis, the compressor and expander still exhibit the highest avoidable exergy destruction, whereas the throttle valve and mixer have a small potential. As the endogenous/exogenous exergy analysis show, the exogenous exergy destruction of almost all components only accounted for a small part of the total destruction, which means the interactions between the components are weak. In a short word, advanced exergy analysis method might lead to a different optimization priority and indicate the interactions between components, which are weak and intricate at the same time. The advanced exergy analysis is a powerful complement to conventional exergy analysis. Furthermore, sensitivity investigations revealed the effects of energy charge/discharge pressure, compressor and expander efficiency on the system performance. It's obvious that high charge/discharge pressure and small heat exchange temperature differences bring a positive influence on the performance of the system. The research in this paper provides a reference for SC-CCES optimization design and application.

Key words: supercritical compressed carbon dioxide energy storage system, CO2 cycle, thermodynamic performance, advanced exergy analysis

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