A critical review on the thermal performance of alternating cross-section tubes

Abstract

This paper aims to summarize publications related to new generation of tube geommetry, thermal performance, and flow characteristics in different cross-sectional manners, and the effect of crucial parameters on thermal–hydraulic performance. An alternating cross-sectional tube has an enhanced vorticity without installing vortex generator devices. Multi-longitudinal vortices are induced along the length of the tube: this makes a significant enhancement in the thermal performance of the tube. Many published papers have focused on the heat transfer and flow characteristics of the alternating cross-section tubes in various configurations in the past two decades.Although the cross-sections had different shapes, the flow behaviors and vortex generation were similar. The geometric parameters, like aspect ratio, pitch length, transition length, alternating angle, phase-shifting, and the total length, influenced the thermal–hydraulic performance of the alternating cross-section tube. The flow characteristics in an annular region differed between the alternating cross-section tube as internal and external tubes. Moreover, some researchers proposed the Nu and f correlations for the practical design of heat exchangers. Finally, future research works and improvement guidelines for alternating cross-section tubes are revealed.

Keywords

• Alternating cross-section tube
• Deformed tube
• Enhanced tube
• Heat transfer enhancement
• Multi-longitudinal vortices
• Vortex generation