Investigation of Heat Transfer Non-uniformity between sCO2 and LBE in Asymmetric Compact Printed Circuit Heat Exchanger

Against the application scenario of lead-cooled fast reactors, the study investigates the heat transfer characteristics and temperature non-uniformity between supercritical carbon dioxide (sCO₂) and lead-bismuth eutectic (LBE) in an asymmetric compact printed circuit heat exchanger (ACPCHE), with a focus on the influence of conjugate heat transfer. The numerical model is established with the SST k-ω turbulence model and the Cheng-Tak model for precise calculation of the turbulent Prandtl number of LBE. Eight adjusted operational conditions with 20% variations in the mass flow rates of LBE and sCO₂ are complemented to the standard condition. The results reveal that the mass flow rate of sCO₂ dominates heat transfer performance (±14% influence on the dimensionless convective heat transfer coefficient) and temperature non-uniformity, while the mass flow rate of LBE has a minor impact (±4%). Axial conjugate heat transfer in plates exacerbates local temperature gradients, particularly affecting the LBE outlet and sCO₂ channel bends—key regions with pronounced non-uniformity. A 20% increase in the mass flow rate of LBE enhances heat transfer quantity by 3.1%, and a 20% decrease in the mass flow rate of sCO₂ aggravates LBE channel non-uniformity. Heat transfer efficiency exhibits an inverse correlation with the mass flow rate of sCO₂ due to heat capacity flow mismatch. These findings highlight the synergistic effects of sCO₂ flow regulation and conjugate heat transfer on non-uniformity, providing a theoretical basis for optimizing heat exchangers in lead-cooled fast reactors and sCO₂ coupling systems.