Dynamic characteristics of the recuperator thermal performance in a S–CO2 Brayton cycle

We introduced a 1-dimensional dynamic model to study the thermodynamic parameter evolution process of the recuperator in a S–CO₂ Brayton cycle, in which we considered the dependency between the S–CO₂'s physical properties of and its temperature/pressure as well as the distribution of the thermodynamic parameters along flow direction. We simulated the start-up process of the recuperator and calculated the changes of thermodynamic parameter fields with time. The thermodynamic parameters at the nodes or elements near hot end took the lead in changing and achieving a stable state. And the thermodynamic parameters such as heat transfer coefficient violently changed along flow direction, especially near the cold end. We calculated the dynamic response process of thermodynamic parameters in recuperator, when generation load ratio gradually decreased from 100% to 50%. It is found that there was an intersection between the hot/cold fluid temperature curves under different generation loads. And the temperature change ranges of cold and hot fluids at recuperator outlets are respectively 730.64–778.82 K and 386.52–384.79 K. The introduced 1-dimensional dynamic model of recuperator and the calculated results may lay foundations for the dynamic simulation and the control system design of the S–CO₂ Brayton cycle.