Thermal and mechanical performance of a hybrid printed circuit heat exchanger used for supercritical carbon dioxide Brayton cycle

Abstract

Printed circuit heat exchangers with high heat transfer efficiency, small volume and high pressure resistance are usually chosen as a precooler for the supercritical carbon dioxide Brayton cycle. The supercritical carbon dioxide channel has high pressure and small mass flow rate, but the water channel has low pressure and large mass flow rate. The conventional printed circuit heat exchanger does not consider the difference between the two-side channels, and thus the weight is large. In this work, a diffusion-bonded hybrid printed circuit heat exchanger is put forward as the precooler used for supercritical carbon dioxide Brayton cycle. The new structure uses chemical-etching channels for the supercritical carbon dioxide side and plate-fin channels for the water side. Thermal design of the hybrid printed circuit heat exchanger based on a segmented Log-Mean Temperature Difference method is conducted. The results indicate that the hybrid printed circuit heat exchanger can effectively improve the heat transfer performance. Compared with the conventional printed circuit heat exchanger, the core volume of the optimized hybrid printed circuit heat exchanger is reduced by 49%, and the heat transfer rate per unit volume is increased by 145%. The optimized hybrid printed circuit heat exchanger in both channels can satisfy the mechanical stress requirement.