Thermal-hydraulic performance of novel slotted fusiform fin printed circuit heat exchanger for supercritical CO2 Brayton cycle

Printed circuit heat exchanger (PCHE) is attractive for recuperators in the supercritical CO2 Brayton cycle. The airfoil fin (AFF) PCHE has better flow and thermal performance than conventional PCHE with zigzag-type channels. However, the significant curvature variation at the leading edge of AFF increases local flow resistance greatly. In this study, a novel slotted fusiform fin (SFF) is proposed to reduce pressure drop and improve comprehensive performance of AFF PCHE. The computational model simplification method is first studied. With less computational cost and guaranteed accuracy, the two-channel recuperator model can be replaced by the single fluid domain with constant wall temperature boundary. Then the simplified model is employed to compare thermal and hydraulic performance of channels with AFFs and SFFs. The SFF channel has 18.69%-20.01% smaller Fanning friction factor than the AFF channel meanwhile maintaining almost same total heat transfer rate. In addition, the flow resistance reduction mechanism of SFF is revealed guided by the field synergy principle. It is attributed to reduction of velocity magnitude, uniform velocity distribution and improvement of synergy between velocity and velocity gradient.