Hybrid optimization for structure of printed circuit heat exchanger with airfoil fins

Abstract

The supercritical carbon dioxide (sCO₂) Brayton cycle is a highly efficient thermodynamic process. In the process, Printed Circuit Heat Exchanger (PCHE) is a promising heat transfer device with merits of under high pressures and temperatures. The airfoil fin, as a form of intermittent fin, has garnered considerable interest. Research involving experimental and simulation studies of airfoils primarily focuses on structural improvements, while the optimization of these improved structures remains relatively underexplored. To further enhance the thermal-hydraulic efficiency of Printed Circuit Heat Exchangers (PCHEs), both local and overall performance concerning flow dynamics and heat transfer of PCHEs with uniform airfoils are analyzed. Adopting the concept of enhancing heat transfer in different regions, combining the dense and sparse airfoil fin layouts at different positions, three types of mixed channels are presented. The hydraulic performance and thermal performance of the hybrid channel in various working conditions is compared. It is found that regional enhanced heat transfer is of big advantages to lower the overall pressure drop. Compared with uniform airfoil channel and the other two mixed channels, the total thermohydraulic efficiency of the low-temperature area in densified channel is the best, which is 1.099 time of that in the uniform channel. Compared to the channel in the high-temperature area, pressure drop in the low-temperature area can be reduced by up to 33.8 %. In addition, heat transfer efficiency is improved at a given mass flow rate while the overall pressure drop is significantly reduced in the low-temperature area of densified channel. Additionally, the enhanced flow passages in the low-temperature zone not only lead to a substantial reduction in overall pressure drop but also enhance heat transfer efficiency significantly. The research content and conclusion of this paper can provide a reference for the structure optimization of printed circuit heat exchangers and the optimization of sCO₂ Brayton circulation system.