Design and thermodynamic analysis of supercriticalCO2reheating recompression Brayton cycle coupled with lead‐based reactor

Abstract

A reheating process is generally incorporated in a supercritical CO2 (S-CO2) Brayton cycle to enhance its efficiency. The heat transfer process from the reactor coolant to the working fluid of the power cycle is a key issue encountered when designing reheating power systems for the lead-based reactor. The traditional reheating system, called RH-1, utilizes an intermediate coolant circuit. In this paper, a novel reheating system, called RH-2, is proposed. It eliminates the intermediate coolant circuit and combines the processes of the primary heating and reheating in a single heat exchanger. A thermodynamic analysis of three different systems for the lead-based reactor integrated with the S-CO2 power cycle with or without reheating was conducted to evaluate the performance of the proposed system. The results confirmed that the performance of RH-2 was the best of all the three systems. Under the same reactor conditions, the system efficiency of RH-2 was greater than those of RH-1 and the recompression (no reheating) system by 1.2% and 1.7%, respectively. RH-2 could also maintain higher efficiency when the main operating parameters varied. The efficiency of RH-2 was higher at different core outlet temperatures and split ratios. The maximum efficiency at optimal maximum pressure of RH-2 was greater than those of the other two systems. RH-2 was less sensitive to the variations in the isentropic efficiencies of the components than the other two systems, while the turbine isentropic efficiency demonstrated a significantly higher impact on the system efficiency than the two compressors (approximately 3.8 times).