Analysis Of Supercritical CO₂ Solar Thermal System Performance Based On Brayton Cycle

The S-CO₂ thermodynamic cycle shows better system performance than other brayton cycle,and has high potential in tower solar thermal power generation and nuclear power generation industries.In this dissertation,the S-CO₂ thermal power generation system model based on the closed brayton cycle is established.The system characteristics of the steady-state system and the solar collector are studied by simulation.The characteristics of variable operating conditions under different actual solar input conditions are studied The conclusions and relevant values obtained are as follows:Firstly,the mathematical model of the S-CO₂ system is established and verificated,the calculation method of the total solar radiation intensity received by the mirror field is determined.The analysis method of the system is given through the system gray-box network model.S-CO₂ cycle showed better system performance,high thermal cycling efficiency at low TIT,the thermal efficiency is 28.2%for TIT at 700 K,and 42.02%for TIT at 1100 K.The optimum working temperature of solar collectors is 1130K.The influence of key parameters on the performance of S-CO₂ system is analyzed by the coupling collector.The results show that the optimal pressure ratio is5 for the system model The higher the efficiency of the thermal power generation system,the lower the total efficiency;improve the heat recovery can effectively improve the system performance;cooler system in the largest loss of the link.Finally,Finally,the operating mode of the system under the whole day operating condition is designed.The results show that the solar irradiation condition is better,the average efficiency of the collector is lower in the daytime mode,47.78%in the summer solstice,54.87%in the winter solstice;The greater the cumulative output power of the system,the higher the thermal efficiency,but the lower the total efficiency of the system.Poor operating conditions require longer nighttime operating conditions,changing the design conditions to keep the system running throughout the day.