具备近似等压放电过程的近似等温压缩CO₂ 储能系统特性研究

In order to supply(near)stable electricity to some small-scale special load, a near-isothermal compressed CO₂ energy storage system with near constant discharge process is proposed in this paper based on the basic principle of near-isothermal compressed air energy storage by applying the liquid piston, the heat transfer method via helical coil in pressure vessel wall and the gas/liquid phase change process. Firstly, the thermodynamic analysis models of the core components of this system are established and the performance indicators are given. Then, the performance analysis in the initial round trip cycle of such system is analyzed. The parameter sensitivity analysis is also conducted, including the parameters of initial pressure of pressure vessel, maximum pressure of pressure vessel and water temperature in helical coil. Finally, the effect of heat transfer with and without helical coil configuration(on system performance is carried out. The results show that the round trip efficiency, thermal efficiency and energy density of the system are 62.67%, 53.05% and 0.500 3 kW·h·m-3, respectively. Meanwhile, the system also exhibits a near constant power output in the discharge process, which varies between 636 and 840 kW. The work of this paper can enrich the theoretical system of compressed gas energy storage, and has important practical value and significance.