Multi-objective optimization of outward convex corrugated tubes using response surface methodology

Multi-objective optimal designs of high efficiency corrugated tube heat exchangers applied in nuclear plants are presented in this paper. Dimensionless corrugation pitch (p/D), dimensionless corrugation height (H/D), dimensionless corrugation radius (r/D) and Reynolds number (Re) were considered as four design parameters. The analyses of heat transfer characteristic, resistance characteristic and overall heat transfer performance for the corrugated tube were conducted based on CFD to acquire the objective functions (Nuc, fc, Nuc/Nus, fc/fs and η in this paper) for combination of process parameters. The Response surface methodology (RSM) with Central composite design (CCD) was used to identify the relationships between the objective functions and the design variables. Variance of the linear term, quadratic term and interactive term for design parameters in the response variables were analyzed. Response surface analyses were applied to visualize the effects of the interactive term. The results of optimal designs are a set of multiple optimum solutions, called ‘Pareto optimal solutions’. It reveals that augmenting the heat transfer performance caused by various design parameters in the optimum situation would lead to the increase of the resistance. The optimum values of fc/fs = 1.22 and η = 1.42 are obtained in the condition of specific (fixed) Nuc/Nus ≥ 1.2.