Dynamic Modeling of the Supercritical Carbon Dioxide Simple Recuperated Brayton Cycle

Abstract

With the development of the GEN-IV nuclear reactors in the 21st Century, as a substitute for the steam cycle, the supercritical carbon dioxide (SCO2) Brayton cycle has been widely used in a variety of power generation scenarios and has attracted widely attention from the scholars. However, the previous research mainly focused on the basic thermodynamics research, parameter optimizations and system design. Considering the load variability and control flexibility of the power generation system, the dynamic performance research of the SCO2 cycle is necessary. In the numerous layouts of SCO2 Brayton cycle, the SCO2 simple recuperated cycle stands out for its simple structure and high efficiency, which is also the main focus in this paper. In this paper, a dynamic model of SCO2 simple recuperated brayton cycle is developed with the Simulink software. The overall system includes a turbine (T), compressor (CM), regenerator (Re), intermediate heat exchanger (IHE), pre-cooler (PC), surge tank (ST), and heater. The models could be able to realize independent physical functions and be mathematically independent. The SCO2 recuperated cycle is then built with the developed models. Based on the simple recuperated system, the comparative calculation with the design value is carried out to verify the models and the results are very positive. Since the components are tightly coupled in the closed-loop cycle, the error of the main parameters for each component is relatively large. In the steady calculation, the maximum error of the component parameter is 7.72%, and the error of the cycle efficiency is about 1.45%. The results are very promising that the developed model has the ability to evaluate the thermal-hydraulic characteristics of the SCO2 Brayton circulation system.