Numerical study on flow distribution of supercritical CO2 in multiple channels of printed circuit heat exchanger

The printed circuit heat exchanger (PCHE) is a promising candidate in the application of the supercritical CO2 Brayton cycle. The flow maldistribution of PCHE is a practical issue due to the multi-channels in the core region, which may affect the performance of PCHE in the operation. Therefore, in this paper, the flow distribution and thermohydraulic characteristics of PCHE with three different channel configurations including the straight channel, wavy channel, and airfoil channel are investigated. The flow non-uniformity with two types of headers (free manifold and straight rib manifold) is compared among the three configurations under different mass flow rates. Based on the results, it is found that the core region of PCHE with larger flow resistance shows better flow uniformity and heat transfer performance. And the header structure is of great significance to the flow distribution based on the analysis of flow vector contours. Therefore, a modified manifold, with bent fins and airfoil fins, is proposed to improve the flow maldistribution of PCHE. Compared to the free manifold and straight rib manifold, the flow non-uniformity of the modified manifold is reduced by 39.4% and 61.8%, respectively; and the overall performance is averagely increased by 5% and 8.5%, respectively. Hence, it is recommended that the designers adopt the modified manifold for the performance improvement of integrated PCHE.