Compressed Carbon Dioxide Energy Storage (CCES) is a new type of energy storage technology that adapts to large-scale integration of new energy, ensuring the safe and stable operation of new power systems. With advantages such as being environmentally friendly, highly efficient, strong adaptability to operating conditions, and good energy storage stability, it has broad engineering application prospects in power peak regulation, frequency regulation, and long-duration energy storage, and is a current hotspot in energy storage technology research. 

[Objective] To further optimize the actual operating performance of low-pressure compressed carbon dioxide energy storage systems and improve the system operation and control framework, this paper conducts a dedicated study on the operating characteristics of the low-pressure energy release phase in low-pressure CCES systems, investigating the influence of key operating parameters on the overall energy release performance of the system, providing reliable experimental support and theoretical basis for the engineering implementation, parameter optimization, and stable operation of low-pressure CCES systems. 

[Methods] This study focuses on a 0-1 MPa low-pressure compressed carbon dioxide energy storage system, concentrating on the core control elements during the energy release process. Through controlled variable experiments, the influence of two major parameters—valve opening and heating temperature—on key performance indicators, such as energy release duration, output power, and operational stability, is systematically investigated. 

[Results] The results indicate that within the experimental conditions of this study, valve opening is the core parameter affecting the energy release performance of low-pressure CCES systems, significantly regulating the continuity of energy release. Compared with the fully open (100%) condition, a 40% valve opening condition effectively extends the energy release duration by 28%, greatly enhancing the system's long-term continuous energy release capability. Meanwhile, heating temperature can effectively increase the power output of the expander, with the 70°C heating condition showing a more pronounced power improvement than the 60°C condition, particularly under valve openings less than 50%. 

[Conclusion] Valve opening and heating temperature are key parameters for regulating the energy release characteristics of low-pressure CCES systems. Considering the comparison of operational stability, power generation, and energy release duration, within the experimental range of this study, the 50% valve opening combined with 70°C heating condition performs better in meeting long-duration energy release demands while balancing energy release continuity and operational stability. Under this condition, the power fluctuation amplitude is only one-third of that under the fully open condition, making it suitable for long-term stable energy release in power systems and providing an important reference for the practical operation and control of low-pressure CCES systems.