NUMERICAL STUDY OF FLOW STRUCTURE AND THERMOHYDRAULIC PERFORMANCE OF SCO₂ IN S-SHAPED PRINTED CIRCUIT HEAT EXCHANGER WITH LONGITUDINAL RIBS

摘要

Printed circuit heat exchanger (PCHE) is an excellent candidate for the supercritical carbon dioxide Brayton cycle due to its high power, high efficiency, and compactness. Manufactured with diffusion welding process, PCHE can work in high-temperature and high-pressure conditions with good structural stability. Compared with the Z-shaped PCHE, the S-shaped PCHE has a comparable heat exchange capacity with a less pressure drop, and is chosen as the research object in this paper. Four different longitudinal ribs, whose width and height are 1/3 of the semicircular arc and radius, are newly introduced into S-shaped channels. Numerical investigations are conducted using supercritical carbon dioxide in both hot and cold sides. The flow structure, local heat transfer coefficient, overall heat exchange performance, and resistance characteristics of rib cases are obtained and compared with the smooth case. The results suggest that the introduction of longitudinal ribs can significantly enhance the heat transfer performance and effectively increase the power per unit volume as well as the efficiency, while producing additional pressure drop. This study has provided reference data for designing high-efficiency PCHE.