Influence of geometric parameters on the gas-side heat transfer and pressure drop characteristics of three-dimensional finned tube

Three-dimensional fin tubes have been used in efficient compact heat exchangers for many years. To further improve the heat transfer efficiency, the Taguchi method is used to study the influence of the structural parameters of three-dimensional finned tubes on the heat transfer and pressure drop characteristics in the air cross-flow. The effects of the fin height, fin width, axial fin pitch and circular fin pitch have been studied, and the contribution ratios of each structural parameter on the thermo-hydraulic performance are given. The results show that the influence of the fin height on the heat transfer and flow resistance is the largest, which should be considered as the preferential factor in the design of three-dimensional finned tubes. The effects of multi-parameters on heat transfer and flow resistance are analyzed. Then, empirical correlations are developed for the Nusselt number and friction factor in the experimental ranges. Finally, the performance evaluation criterion of three-dimensional finned tube is revealed to be 2.7–2.9 times greater than that of the smooth tube. Meanwhile, the order of the four structural parametric effectiveness for the performance evaluation criterion is obtained as fin height > axial fin pitch > circular fin pitch > fin width.