CFD analysis on flow resistance characteristics of six-start spirally corrugated tube

Heat transfer enhancement technology has been widely used in heat exchangers. The six-start spirally corrugated tube is a novel heat transfer tube, and its flow resistance characteristics have not been studied. In this paper, the flow resistance characteristics of the six-start spirally corrugated tube are studied. Specifically, the effect of influencing factors such as geometric parameters (pitch and corrugation depth), fluid properties and Reynolds number on flow resistance of the six-start spirally corrugated tube are studied. The results show that, firstly, the six-start spirally corrugated tube has a better heat transfer performance than both the circular tube and four-start spirally corrugated tube, and its flow resistance is situated between circular tube and four-start spirally corrugated tube. Secondly, with the increasing of the pitch p of the six-start spirally corrugated tube, both the pressure drop Delta P and resistance coefficient f are decreasing gradually. Thirdly, the increase of corrugation depth e can lead to a large flow resistance, so it is not recommended to adopt an excessive increase in the corrugation depth e. The effect of fluid properties on flow resistance in tube is not obvious, and the changing rate of ratio f(e)/f(s) of all working media are almost the same. Moreover, with the increasing of Reynolds number Re, resistance coefficient f both in the six-start spirally corrugated tube and circular tube are decreasing gradually. Finally, based on the above research data, the criterion correlation for flow resistance calculation in the six-start spirally corrugated tube is obtained. It can be concluded that the six-start spirally corrugated tube studied in this paper has a smaller flow resistance than the commonly used four-start spirally corrugated tube. This work can provide some advices for the future research of reducing flow resistance in spirally corrugated tube or other related devices. (C) 2016 Elsevier Ltd. All rights reserved.