对系统余热回收利用的优化是提升储能系统效率的有效途径。本文提出了一种基于能量梯级利用的压缩CO₂储能系统,利用高压压缩余热分级存储的手段实现能量的深度利用。建立了系统的热力学模型,对所提出系统和现有参考系统进行了对比分析。结果表明,改进后的系统循环效率增加了3.99%,储能密度增加4.47 kW.h/m₃^,换热部件相对?损失下降了6.80%。进一步分析表明,该新系统提高冷却水的初始温度能有效提高循环效率,高温储热换热器中CO₂的出口温度对循环效率的影响存在最优值,取值为161℃。中温段换热器中CO₂的出口温度较低时,有利于循环效率和储能密度的提升。研究表明所提出的系统能够为CO₂储能系统深入优化提供一种可行方案。

The optimization of waste heat recovery and utilization is an effective way to improve the efficiency of energy storage system. In this paper, a compressed CO2 energy storage system based on step utilization of energy was proposed, and the deep utilization of energy was realized by means of hierarchical storage of waste heat under high pressure compression. A thermodynamic model of the system was established, and a comparative analysis was made between the proposed system and the existing reference system. The result shows that after the improvement, the cycle efficiency of the system increased by 3.99%, the energy storage density increased by 4.47 kW.h/m3, and the exergy loss of heat exchange parts decreased by 6.80%. Further analysis shows that the new system can effectively improve the circulation efficiency by increasing the initial temperature of cooling water, and the influence of CO2 outlet temperature on the circulation efficiency of high temperature heat storage heat exchanger has an optimal value, which is 161℃. When the outlet temperature of CO2 in the medium temperature heat exchanger is low, it is conducive to the improvement of cycle efficiency and energy storage density. The research shows that the proposed system can provide a feasible scheme for further optimization of CO2 energy storage system.

TK221

国家自然科学基金项目（51774143）