Parametric study and optimization of dimpled tubes based on Response Surface Methodology and desirability approach

In this paper, parametric study and optimization of dimpled tubes based on Response Surface Methodology and desirability approach were carried out. The diameter of dimples, the ratio of the depth and the diameter, the ratio of the spacing between two axially adjacent dimples and the diameter, and the quantity of dimples in a transverse cross-section of dimpled tubes were chosen as the design parameters. And the dimensionless characteristic parameters of heat transfer and resistance: Nu/Nu(s) and (f/f(s))(1/3) were adopted as responses. Firstly, a numerical model of dimpled tubes with polyhedral mesh based on Star-CCM+ 12 was established and verified by comparing with experimental results. Secondly, the modified quadratic regression and the modified two-factor interaction (2FI) model were obtained after conducting the analysis of variance (ANOVA) and the interactive effects of four geometrical parameters on Nu/Nus and (f/f(s))(1/3) were discussed. The results show that interactive effects among the four geometrical parameters are significant and complicated because one factor affects the impact of another factor on Nu/Nu(s) and (f/f(s))(1/3). Eventually, optimized parameters are obtained using the desirability approach with the goal of maximum Nu/Nu(s) and minimum (f/f(s))(1/3). (C) 2019 Elsevier Ltd. All rights reserved.