Thermodynamic analysis and performance evaluation of a novel energy storage-based supercritical CO2 power system with ejector driven by nuclear energy

Abstract

The application of supercritical CO2 (S-CO2) in power generation systems shows huge advantages of compactness and high efficiency for nuclear energy utilization. However, it is difficult to achieve a quick response for reactor power regulation system in isolated power gird, and amounts of nuclear heat is wasted by bypass regulation to track the power load. In this paper, a novel energy storage-based supercritical CO2 power system with ejector is proposed to realize the rapid energy storage and energy release in system operation to guarantee high conversion efficiency of nuclear energy. Thermodynamic mathematical models are established to examine the performance of the proposed system. The parametric analysis and optimization are performed to acquire the optimum system performance. Furthermore, the performance evaluation in energy storage conditions and energy release conditions are presented to show the power regulation capacity of the proposed system. Results show that the appropriate split ratios of recompression supercritical CO2 power system for different main compressor outlet pressures are both about 0.3. The optimum thermal efficiency of the proposed system is 44.58% and the corresponding exergy efficiency is 66.94% under the given system conditions. In addition, 10% of mass flow rate storage for the S-CO2 results in a decrease in power load of 41.2%, and 10% of mass flow rate release for the S-CO2 can achieve an increase in power load of 45.59%. Furthermore, the maximum regulation capacity for the power load increases with the pressure of the high-pressure energy storage tank. Meanwhile, the energy release conditions with a low pressure of high-pressure energy storage tank and a high entrainment ratio of the ejector result in the decrease in net power output.