COMPARATIVE ANALYSIS OF AIRSIDE THERMAL-HYDRAULIC PERFORMANCE OF FINS IN HEAT EXCHANGERS UNDER HUMID CONDITIONS

Compact heat exchangers in air-conditioning and electronics applications rely on fin geometry to optimize air-side performance. Prior thermal-hydraulic comparisons under condensation were scarce and often limited to a single fin type or dry operation. This study compared plain, offset strip, and pin fins under humid conditions. Forty-three geometries were generated and simulated in ANSYS Fluent with 3D Volume of Fluid and species transport over Re = 250-4000, using script-based Scheme language automation. Evaluation covered Colburn “j”, Fanning “f”, compactness indices, an equal-pumping-power criterion, and a cluster analysis. Offset strip fins delivered the highest heat transfer with friction losses of a similar order to pin fins under equal pumping power required. Pin fins showed intermediate “j” and “f ”. Plain fins performed the worst among all geometries. Square pins raised the “j” above the matched offset strip case but incurred much higher “f ” values. Condensation increased “j” and “f ” for all fin types. At a fixed pumping power of 10¹⁴ W/m², offset strip fins achieved higher heat transfer than pins and plain fins with reasonable friction losses. Compactness maps placed offset strips in the high heat transfer region, pins in the middle, and plain fins at low heat transfer. Unified wet-surface correlations for “j” and “f ”, based on Reynolds number and D_h-scaled geometry ratios with shape and arrangement factors for pins, predicted within about 5 percent. The presented correlations are capable of prediction and reproducibility.