Numerical and Optimization Study on a Heat Exchanger Tube Inserted with Ring by Taguchi Approach

Abstract

This paper presents an optimization study on a heat exchanger tube inserted with circular rings by using numerical analysis results. Pitch length (50, 100, and 200 mm), inner diameter (15, 12.5, and 10.0 mm), and thickness (1, 3, and 5 mm) of the rings are considered as factors to be optimized. Water is selected as working fluid and the tube is considered under constant heat flux of 20 kW/m2 and turbulent flow conditions. k-Epsilon simulate the turbulent flow through the tube. The L9 design of experiment model is used to reduce the number of numerical runs which is proposed by the Taguchi method. The optimization study is conducted as single and multi-objective optimization by using the Taguchi method and Grey relation analysis. Furthermore, the contribution effects of the considered parameters on the Nusselt number and the friction factor result are revealed by ANOVA. Numerical results showed that the Nusselt number and the friction factor increase as the pitch length, the diameter and the thickness decreases. It is found that the most effective parameter on both the Nusselt number and the friction factor is inner diameter of the rings. For the single objective optimization, the highest Nusselt number and the lowest friction factor is obtained with the tube configuration that are found as the pitch length of 50 mm, the diameter of 10 mm and the thickness of 5 mm and the pitch length of 200 mm, the diameter of 15 mm and the thickness of 3.0 mm, respectively. The pitch length of 50 mm, the diameter of 15.0 mm and the thickness of 5.0 mm presents the best thermal and hydraulic performance according to the multi-objective optimization study.