储换热单元优化的液态存储压缩CO₂储能系统性能提升

Abstract: To balance the energy storage efficiency and density of liquid compressed CO₂ energy storage (L-CCES) technology, a novel L-CCES system is proposed and optimized based on a system design philosophy of "minimizing supplementary heating and waste heat rejection". Firstly, based on the established thermodynamic model of the L-CCES system- combined with exergy analysis, the effects of the heal storage medium flow distribution ratio and ihe heat storage medium-lo-CO₂ flow ratio on the thermal performance of a typical L-CCES system configuralion were investigated. The exergy loss of the typical system was analyzed, and the energy conversion characteristics were also revealed. Building on this, the heat storage and exchange unit-identified as the largest contributor to exergy loss in the typical system—was targeted to improve the uniformity of heal exchange in the heal storage medium. By considering practical engineering applications, enhancements such as adding an inlercooler and optimizing the inlercooling temperature were implemented to further boost energy storage efficiency. The results show that the energy storage efficiency of the typical L-CCES system is 64.65%, with its heal storage and exchange unit accounting for the highest exergy loss at 59.7%, indicating thai matching the quantity and grade (temperature) of stored heal is key lo improving system efficiency. In contrast, when ihe inlercooling lemperature is optimized lo 46 °C , the novel system achieves grealer heal exchange uniformity of the storage medium. Consequently, the exergy loss of its heal storage and exchange unit decreases by 16.7% compared lo ihe typical system, the total exergy loss drops from 218.69 MW • h lo 198.82 MW • h, and the energy storage efficiency increases to 66.80%. This sludy provides theoretical guidance for ihe optimal design of L-CCES systems.