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Journal of Enhanced Heat Transfer
IF: 0.562 5-Year IF: 0.605 SJR: 0.211 SNIP: 0.361 CiteScore™: 0.33

ISSN Print: 1065-5131
ISSN Online: 1563-5074

Journal of Enhanced Heat Transfer

DOI: 10.1615/JEnhHeatTransf.v16.i4.10
pages 315-329

Effects of Vortex Generator Arrangements on Heat Transfer Enhancement over a Two-Row Fin-and-Tube Heat Exchanger

M. Mustafa Akbari
Department of Mechanical Systems Engineering, Graduate School of Engineering, Tokyo University of Agriculture and Technology, Japan
Akira Murata
Department of Mechanical Systems Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan
Sadanari Mochizuki
Tokyo University of Agriculture and Technology, 2-24-16, Naka-cho, Koganei-shi, Tokyo 184, JAPAN
Hiroshi Saito
Mechanical Systems Engineering Course, Tokyo Metropolitan College of Industrial Technology, 1-10-40 Higashi-Ohi, Shinagawa, Tokyo 140-0011, Japan
Kaoru Iwamoto
Department of Mechanical Engineering, Tokyo University of Science, Noda-shi, Chiba 278-8510; Department of Mechanical System Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan

ABSTRACT

Heat transfer enhancement effects of two different configurations of delta-winglet pair vortex generators were experimentally studied in a narrow rectangular channel. This geometric configuration simulated a single passage of a two-row fin-and-tube heat exchanger. The local heat-transfer coefficient distributions on the surface with vortex generators and the opposing smooth surface were determined using an infrared camera. The flow behavior and structure of vortices were visualized by using the water and dye-injection method. The heat transfer enhancement with the pressure loss being taken into account was also investigated. The Reynolds number, Re, based on two-times of channel height and channel mean flow velocity ranged from 500 to 2000. Three arrangements of the vortex generator were suggested by installing delta-winglet pair vortex generators on the first and second rows. As a result, changes in local and spanwise-averaged Nusselt numbers on both the surfaces with and without vortex generators, and in the flow structure were observed by increasing the Reynolds number. Particularly, regions of high heat transfer appeared on the opposing smooth surface, and heat transfer in the wake zone behind the tubes was enhanced by reduced flow separation from the tubes caused by vortex generators.