Numerical Simulation Study of Flow and Heat Transfer Characteristics of Asymmetric Microchannel Intermediate Heat Exchanger

Abstract The combination of a lead-bismuth fast reactor and a supercritical CO2 Brayton cycle is one of the most ideal and efficient power cycles. The printed circuit heat exchanger is best suited for the system’s intermediate heat exchanger. Its thermal and hydraulic performance have a significant impact on the overall system’s circulation efficiency. There are substantial differences between the physical properties of hot and cold fluids. The traditional symmetrical flow channel structure does not adequately meet the requirements. In this paper, a microchannel intermediate heat exchanger with asymmetrical channels on both sides is numerically simulated. The study analyzed the effect of liquid lead-bismuth eutectic (LBE) inlet Reynolds number, flow channel cross-sectional shape, supercritical carbon dioxide (S-CO2) inlet Reynolds number, and inlet temperature on the thermal and hydraulic performance of the intermediate heat exchanger (IHX). The study investigated the effect of different parameters on the Nusselt number, heat transfer coefficient, and Fanning friction factor on both sides of the heat exchanger. The performance of the intermediate heat exchanger was assessed using performance evaluation criteria. The results show that the IHX performance is insensitive to changes in the Reynolds number and cross-section shape of the hot side flow channel. The heat transfer performance of the cold side is significantly inferior to that of the hot side. Changing the cold side parameters can affect the performance of the IHX to a greater extent. Increasing the inlet temperature of the S-CO2 has less impact on the performance of the IHX than increasing the Reynolds number.