Multi-objective optimization of self-excited oscillation heat exchange tube based on multiple concepts

It is a typical multi-objective optimization problem for self-excited oscillation heat exchange tube to enhance heat transfer by limiting pressure drop. In this study, the conflict between heat transfer and pressure drop is solved by multi-objective optimization method. The design parameters are three dimensionless structural parameters, which are collision wall angle (100 degrees < alpha < 140 degrees), the diameter ratio of chamber outlet to inlet (0.8 < d2/d1 < 1.6) and the length-to-diameter ratio of chamber (0.4 < LT/DT < 0.6). The purpose of optimization is to compromise Nusselt number Nu and friction factor f. The sample points are obtained by CCD. The RSM models of Nu and f are constructed, and variance analysis and sensitivity analysis are carried out for the models. Finally, the Pareto front is obtained by NSGA-II and verified by CFD, the compromise solution is obtained by TOPSIS method. The results show that the most significant factor of Nu and f is d2/d1. The optimized structural parameters of the compromise solution are alpha = 125.67 degrees, d2/d1 = 1.2505, LT/DT = 0.4036, and the corresponding Nu and f are 149.8528 and 0.1144, respectively. Compared with the original structure, Nu increases by 1.54% and f decreases by 27.37%, which indicates that the convective heat transfer is enhanced and the flow resistance is significantly reduced.

Automated summary

This study addresses the conflict between heat transfer and pressure drop in self-excited oscillation heat exchange tubes through multi-objective optimization. By compromising the Nusselt number Nu and friction factor f, the optimized structural parameters are obtained, resulting in enhanced convective heat transfer and significantly reduced flow resistance.