Experimental and numerical analysis for effects of using conical ring on turbulent flow and heat transfer in a double pipe air to water heat exchanger

Effect of typical and perforated conical ring turbulators on hydrothermal behavior of air to water double pipe heat exchanger is investigated. Two arrays (Direct conical ring (DCR) array and Reverse conical ring (RCR) array) are considered. Experimental analysis is examined for different values of open area ratio (0-0.0833), Reynolds number (6000-12,000), conical angle (0 degrees-30 degrees) and pitch ratio (1.83-5.83). Correlations for friction factor, Nusselt number and thermal performance factor are presented. To reach the optimal design, Non Sorting Genetic Algorithm II is applied. Pareto front of optimized solution is presented. Also the finite volume method (commercial code) is utilized for numerical section in order to show physical phenomena. Results indicate that friction factor reduces with augment of open area ratio, pitch ratio and Reynolds number. Nusselt number reduces with increase of open area ratio and pitch ratio while it augments with enhance of Reynolds number. Also it can be concluded that thermal performance rises with augment of conical angle for direct conical ring array. (C) 2016 Elsevier Ltd. All rights reserved.