Effects of position and geometry of curved vortex generators on fin-tube heat-exchanger performance characteristics. (5th May 2021)

• Record Type: Journal Article
• Authors: Oh, Yeongtaek; Kim, Kuisoon
• Is Part Of: Applied thermal engineering. Volume 189(2021)
• Publication Date: 2021-05-05
• Subjects: Fin-tube heat exchanger -- Curved vortex generator -- Heat-transfer enhancement -- Pressure loss -- Numerical simulation; Heat engineering -- Periodicals; Heating -- Equipment and supplies -- Periodicals; Periodicals; 621.40205
• DOI: 10.1016/j.applthermaleng.2021.116736
• Languages: English
• ISSNs: 1359-4311

Abstract

Highlights: Curved vortex generators (CVGs) were evaluated in a fin-tube heat exchanger. The position and geometry of the CVGs were parametrically studied. The resulting wakes, vortices, and corresponding heat transfer were compared. Delta winglet CVGs were found to provide improved heat transfer performance. Abstract: The thermal and fluid-flow characteristics of the rectangular-winglet, delta-winglet-upstream (DWU), and delta-winglet-downstream (DWD) curved vortex generators (CVGs) are computationally analyzed in this study. Polar coordinates based on the tube center are considered to define the CVG positions, thereby facilitating a parametric study of the effects of the position angle ( α ) and radial distance ( r ) of CVGs. The resulting heat-transfer enhancement, pressure loss, and flow patterns have been analyzed in detail. When CVGs are placed at α = 30 °, mixed vortices are generated, thereby improving the heat-transfer performance of the fin. In contrast, placing the CVGs near the rear of the tube reduces the wake size and increases heat transfer behind the tube. Furthermore, a secondary flow is induced enhancing the fine heat-transfer performance. However, the most of results obtained in this study reveal that CVGs are not superior to conventional VGs. Further, the realization of optimum heat-transfer performance using CVGs mandates certain position and geometry requirements to be satisfied. For example, as observed in this study, the DWU CVGs ( α = 105 °, r / R = 1.25 ) and DWD CVGs ( α = 30 °, r / R = 1.5 ) exhibit the highest heat-transfer performance improvements of 5.2% and 7.5%, respectively, compared to conventional VGs. However, this enhancement in heat-transfer performance is realized at the cost of a relatively small pressure loss.