Comparative Analysis of Airside Thermal–Hydraulic Behavior of Plain, Wavy, and Louver Fins under Humid Conditions

Compact heat exchangers in HVAC and automotives rely upon plain, wavy, and louver fins to achieve required airside performance under limited volume limits. Most prior studies have evaluated one fin family or dry operation, which has limited the design transfer to humid conditions and proper comparison. Consistent comparisons under condensation with unified metrics are scarce. This study compared plain, wavy and louver fins. Forty-eight geometries with three fin types were modeled using FreeCAD scripts and simulated in ANSYS Fluent using 3D Volume of Fluid with species transport over Re = 250–4000. Wet Colburn “j”, Fanning “f”, compactness-based indices, and constant pumping power per unit area were evaluated. This study further compared the thermal–hydraulic performance of these three fin types under similar geometric conditions, as well as through a cluster-based comparison. Louver fins delivered the highest heat transfer with high friction losses, governed by louver angle and the louver-to-fin pitch ratios. Wavy fins achieved intermediate heat transfer with moderate friction losses, controlled by amplitude to wavelength and other geometric parameters. Plain fins performed the worst, while delta winglet vortex generators raised heat transfer at low to intermediate pumping power with a geometry-dependent rise in friction losses. Unified wet-surface correlations for “j” and “f” were developed, as functions of Reynolds number and non-dimensional geometry ratios. The correlations predicted within about 10 percent across all fin types and proposed ready-to-use correlations for prediction.