Thermal hydraulic performance of printed circuit heat exchanger with various channel configurations and arc ribs for SCO2 Brayton cycle

Printed circuit heat exchanger (PCHE) is an efficient and high-compactness heat exchanger which can withstand extreme conditions of high temperature and high pressure, thus is a promising candidate in the nuclear, marine propulsion and power applications. In this paper, eight multi flow paths (MFP) PCHEs with different channel configurations are proposed, and seven kinds of arc ribs, including continuous and discontinuous 1/3 ribs, 2/3 ribs and semi-circular ribs, are innovatively introduced into MFP channels. Numerical investigations are carried out to explore the local and overall thermal hydraulic performances of various MFP-PCHEs in supercritical carbon dioxide (SCO2) Brayton cycle, and to figure out the effects of channel configuration and arc rib arrangement systematically. Additionally, the improvement in system performances of SCO2 Brayton cycle is further evaluated when the MFP-PCHEs are applied as recuperator. The results show that the 90 degrees turning bend and arc rib effectively enhance the fluid disturbance by the impingement and acceleration effects, contributing to the augmentation of turbulence kinetic energy (TKE) and heat transfer level. The increase of flow path is also helpful to improve the overall thermal performance. Among all the MFP-PCHEs, the C3 (with 14 turning bends) produces the largest Nusselt number, with 16.6%-30.6% improvement compared with the straight channel (C0 case), at the same time its friction is 3.41-4.90 times of C0 case. The maximum heat exchanger effectiveness is obtained in C7 case (with 12 turning bends) at the Re of 30,000, which is 75.5%. According to the simulation results, the correlations of Nusselt number and friction factor for hot and cold channels of eight MFP-PCHEs are developed. Moreover, the adopt of semi-circular rib (R5) improves the Nusselt number by 7.3%. For a SCO(2 )Brayton cycle, the adoption of MFP-PCHEs can effectively enhance the system energy efficiency, and the improvement effect will reach 41.2% when the C3 configuration is applied. This research has provided critical data support for the development of MFP-PCHE in SCO2 Bryton cycle. (C) 2019 Elsevier Ltd. All rights reserved.