Investigation of local flow and heat transfer of supercritical LNG in airfoil channels with different vortex generators using field synergy principle

Vortex generators（VGs） have gained significant attention as a potential technology for enhancing heat transfer. This study introduces a novel delta airfoil VG with the objective of improving the heat transfer efficiency of heat exchangers. The overall heat transfer performance of four types of printed circuit heat exchanger (PCHE) channels is evaluated using three-dimensional numerical analysis in this paper. These channels comprise of two VGs with different shapes and installations, along with NACA0024 airfoil fins. The delta winglet VG (DWVG), the delta airfoil VG (DAVG), and the delta airfoil staggered VG (DASVG) are the VGs used in the three PCHE channel configurations. The performance of the four PCHE flow channels is assessed using the dimensionless thermal enhancement factor (TEF). To investigate and explain the interaction between VG and flow structure distribution as well as heat transfer, the secondary flow number Se and the field synergy principle are employed. The results show that the local field synergy angle of the channel with VG is smaller than that of the non-VG baseline case, indicating the best enhanced heat transfer in the pseudo-critical region. Among the four cases, the DAVG exhibits the best hydrothermal performance, and the local heat transfer coefficient can be increased up to 120%, which aligns with the interpretation of the field synergy principle.