In a supercritical carbon dioxide (sCO2) solar thermal power plant system using solid particle as the heat absorption and transfer medium, the concentrating-receiver-heat exchange coupled system composed of a heliostat field, solar particle receiver, and particle/sCO2 heat exchanger is one of the most important subsystems in the power plant system, and its dynamic characteristics directly affect the performance of the whole system. In this paper, taking the 200kWe sCO2 solar thermal power plant as the research objective, firstly, a discretized lumped parameter model of the coupled system was established to study the dynamic performance and operational characteristics based on the TRNSYS platform, and the following characteristics of some key parameters such as particle and sCO2 outlet temperature to the DNI variation were deeply studied without taking any control measures. The results indicate that the particle and sCO2 outlet temperature are positively correlated with the DNI variation and are highly sensitive, and the efficiency of the particle receiver is basically maintained at around 0.7 whether it is sunny or cloudy; Secondly, in order to achieve the rated outlet design parameters, the dynamic characteristics on June 13 and 15, 2023 with a PID control strategy were also studied. The results show that the particle outlet temperature can be maintained at 800 °C by controlling the particle inlet mass flowrate in the particle receiver, while the sCO2 outlet temperature can be guaranteed at 550 °C by adjusting the sCO2 inlet mass flowrate in the heat exchanger with the condition of mild DNI variation. Besides, it is also found that, the PID control is unlikely to be effective under severe DNI changes. Therefore, the addition of buffer particle tanks is essential to compensate for the intermittency of the DNI in the system design process.
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