储能科学与技术 ›› 2025, Vol. 14 ›› Issue (7): 2761-2771.doi: 10.19799/j.cnki.2095-4239.2025.0050

• 第十三届储能国际峰会暨展览会专辑 • 上一篇    下一篇

液态二氧化碳储能系统变工况运行特性

李源1,2(), 赵明智3,4(), 徐玉杰3,4,5(), 蔡杰1   

  1. 1.南京师范大学能源与机械工程学院,江苏 南京 210042
    2.中科南京未来能源研究院,江苏 南京 211135
    3.中国科学院工程热物理研究所,北京 100190
    4.中国科学院大学工程科学学院,北京 101408
    5.中国科学院长时规模储能重点实验室,北京 100190
  • 收稿日期:2025-01-14 修回日期:2025-02-27 出版日期:2025-07-28 发布日期:2025-07-11
  • 通讯作者: 赵明智,徐玉杰 E-mail:jnzmz80@163.com;zhaomingzhi@iet.cn;xuyujie@iet.cn
  • 作者简介:李源(1999—),男,硕士研究生,研究方向为储能系统,E-mail:jnzmz80@163.com
  • 基金资助:
    2023年南京市新型研发机构联合技术攻关项目(202304008);江苏省碳达峰碳中和科技创新专项重大创新载体建设项目(BM2022001)

Variable-operating-condition operational characteristics of liquid carbon dioxide energy storage systems

Yuan LI1,2(), Mingzhi ZHAO3,4(), Yujie XU3,4,5(), Jie CAI1   

  1. 1.School of Energy and Mechanical Engineering, Nanjing Normal University, Nanjing 210042, Jiangsu, China
    2.Nanjing Institute of Future Energy System, Nanjing 211135, Jiangsu, China
    3.Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190, China
    4.School of Engineering Science, University of Chinese Academy of Sciences, Beijing 101408, China
    5.Key Laboratory of Long-Duration and Large-Scale Energy Storage, Chinese Academy of Sciences, Beijing 100190, China
  • Received:2025-01-14 Revised:2025-02-27 Online:2025-07-28 Published:2025-07-11
  • Contact: Mingzhi ZHAO, Yujie XU E-mail:jnzmz80@163.com;zhaomingzhi@iet.cn;xuyujie@iet.cn

摘要:

储能是实现可再生能源大规模利用的关键支撑技术,液态二氧化碳储能系统具有储能密度高、设备紧凑、安全性高等优点,被认为是具有发展前景的大规模长时储能技术之一。液态二氧化碳储能系统因其闭式双罐结构,实际运行始终处于动态压力与温度变化的变工况状态下。然而现有研究多基于稳态假设,与真实性能偏差较大。因此,本文建立了一种液态二氧化碳储能系统变工况运行模型,揭示了系统变工况运行特性,以及低压罐初始压力、高压罐初始压力、压缩机效率、膨胀机效率、环境温度等关键参数对变工况系统性能的影响;揭示了系统㶲损分布特性,蓄冷器、压缩机和膨胀机是㶲损较大的环节,㶲损占比分别为36.53%、24.63%和19.58%;在典型工况下,高压罐内的二氧化碳(CO2)压力由8MPa上升到14.5 MPa,温度由298.15 K上升至307.32 K,低压罐内CO2压力从0.6 MPa降至0.59 MPa,温度由220 K下降到219.85 K。系统往返效率为63.14%,较稳态假设降低7.21个百分点,储能密度为0.9237 kWh/m3,仅为稳态假设的4.0%,这是因为稳态假设忽略了储罐中存在未利用的工质。本文为二氧化碳储能系统优化设计及应用提供了关键参考。

关键词: 二氧化碳储能, 储能系统, 变工况运行, 往返效率, 能量密度

Abstract:

Energy storage is a critical technology for the large-scale usage of renewable energy. Liquid carbon dioxide (CO2) energy storage systems are recognized as promising large-scale long-duration energy storage technology owing to their high energy density, compact equipment, and enhanced safety. This study establishes a variable-operating-condition model of liquid CO2 energy storage systems to elucidate the dynamic operational characteristics and the impacts of key parameters, including initial pressures of low- and high-pressure tanks, compressor efficiency, expander efficiency, and ambient temperature, on system performance under varying operating conditions. The analysis reveals the distribution of exergy destruction, cold storage units (36.53%), compressors (24.63%), and expanders (19.58%) are the primary sources of exergy destruction. Under typical operating conditions, the high-pressure tank of the system increased from 8 MPa to 14.5 MPa, with the corresponding temperature rise from 298.15 K to 307.32 K. In contrast, the low-pressure tank pressure decreased from 0.6 to 0.59 MPa, with the temperature decreased from 220 K to 219.85 K. In addition, the proposed system achieves a round-trip efficiency of 63.14%, which is 7.2% lower than the steady-state assumptions, with an energy density of 0.9237 kWh/m3—only 3.9% of the steady-state value, due to the exclusion of unused working fluid in steady-state models. These findings provide valuable insights for the optimization design and practical application of CO2 energy storage systems.

Key words: carbon dioxide energy storage, energy storage system, variable-operating-condition operation, roundtrip efficiency, energy density

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