Numerical simulation and structural optimization of airfoil-fin silicon carbide printed circuit board heat exchanger as high-temperature recuperator

Silicon carbide (SiC) material can effectively solve the carbonization and chemical corrosion problems of metallic printed circuit heat exchangers (PCHEs) in supercritical carbon dioxide (S-CO₂) Brayton cycles. This study conducted numerical simulation and structural optimization of the airfoil-fin SiC PCHE as a high-temperature recuperator. The airfoil-fin height, maximum thickness location, vertical pitch, and staggered pitch were selected as the influencing factors, and the Nusselt number ( Nu ), Fanning friction factor ( f ), and comprehensive performance evaluation criterion ( PEC ) were taken as the response values. The response surface method (RSM) was combined to analyze the influence laws of each parameter on the flow and heat transfer characteristics, and to optimizing structural parameters. The results show that the vertical pitch and staggered pitch have the most significant influence on f , while the fin height is the dominant factor determining Nu and PEC . The structural parameters of the optimal comprehensive performance are airfoil-fin height of 1.488 mm, maximum thickness location of 0.291, vertical pitch of 4.396 mm, and staggered pitch of 7.913 mm. Compared to a metallic PCHE with identical geometry, the PEC of the SiC PCHE is increased by 11.1%, which is attributed to the high thermal conductivity of the SiC material. This study provides a theoretical basis and technical support for the design and application of high-performance and corrosion-resistant PCHEs in S-CO₂ Brayton cycles.