| Supercritical carbon dioxide(S-CO2)cycle power generation technology is developing rapidly at both domestic and international levels because of its compact structure,high degree of flexibility and high cycle efficiency.In addition,with the development of renewable energy power generation technology,energy storage technology plays a crucial role in realizing large-scale grid connection of renewable energy.Compared with compressed air energy storage system,compressed supercritical carbon dioxide energy storage system has the advantages of small size and high energy storage density.In this paper,two typical systems of supercritical carbon dioxide Brayton cycle are compared and studied by using Ebsilon software,and the best working conditions are found through optimization;The influence of main parameters such as turbine inlet temperature and pressure,compressor inlet temperature and expansion outlet pressure on cycle efficiency is analyzed;Due to the existence of shunt in the recompression system configuration,the effect of the splitting ratio on the system efficiency is analyzed,and the results show that the system efficiency increases with the increase of the splitting ratio and then decreases,and the optimal splitting ratio exists;the system efficiency of recompression Brayton cycle is significantly higher than that of simple reheat Brayton cycle under the same operating parameters.In this paper,two kinds of compressed carbon dioxide energy storage systems with integrated tower solar energy,simple regenerative compression cycle and recompression cycle,are proposed,and corresponding thermodynamic analysis is carried out.The comprehensive performance of the two systems is compared with energy efficiency,energy storage density,solar efficiency and photoelectric conversion efficiency of solar energy as evaluation indicators.The results show that the energy efficiency of the coupled recompression energy storage system is higher than that of other organic working fluids,because there is available residual heat in the coupled recompression energy storage system,and after comparison,when the transcritical carbon dioxide(T-CO2)is used as the bottom cycle working fluid,the performance evaluation index of the coupled recompression energy storage system is better than that of the coupled simple regenerative compression energy storage system.Furthermore,an evaluation of the technical and economic aspects of both systems is conducted,and the impact of the two main parameters of turbine inlet temperature and energy storage pressure on the economy is compared.The results show that the integrated system with coupled recompression has good economic benefits.The dynamic investment payback period is about 6 to 7 years,and the 20-year net present value(NPV)is 23456.16k$,which is 7956.69k$ higher than the coupled simple regenerative compression system and the internal rate of return(IRR)is 17.55%,which is 5.55%higher than the interest rate(i). |
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