Multi-objective optimization of geometrical parameters of dimples on a dimpled heat exchanger tube by Taguchi based Grey relation analysis and response surface method

Abstract

Taguchi based grey relation analysis (GRA) is performed on the numerical analysis of the dimpled heat exchanger tube for considering various dimple parameters. Dimple diameter (Dd) (3–7 mm), dimple pitch length (PL) (10–30 mm) and dimple height (H) (1.0–1.4 mm) are considered to achieve the highest convective heat transfer coefficient (h) and the lowest pressure drop (ΔP). The analyses are conducted under flow condition that is Reynolds number of 3000. The single-objective optimization is performed by Taguchi analysis, while GRA is used for the multi-objective optimization. Experimental plan is created according to L25 orthogonal array given by Taguchi method. The relatively contribution levels of the parameters on the h and the ΔP are also figure out. Validation of the optimization methodology is ensured by performing a confirmation test. It is resulted that the PL has higher influence on the both h and the ΔP followed by H and Dd in the decreasing order. Dimpled tube configuration having Dd=7 mm, PL=30 mm and H=1.0 mm is found as the optimum configuration giving the highest the h and the lowest ΔP, simultaneously.