Open Access

ARTICLE

3D NUMERICAL ANALYSIS ON FLOW CONFIGURATIONS AND HEAT TRANSFER CHARACTERISTICS FOR FIN-AND-OVAL-TUBE HEAT EXCHANGER WITH V-DOWNSTREAM DELTA WINGLET VORTEX GENERATORS

Amnart Boonloi^a, Withada Jedasadaratanachai^b,*

a Department of Mechanical Engineering Technology, College of Industrial Technology, King Mongkut’s University of Technology North Bangkok, Bangkok 10800, Thailand
b Department of Mechanical Engineering, Faculty of Engineering, King Mongkut’s Institute of Technology Ladkrabang, Bangkok 10520, Thailand

* Corresponding Author: Email:

Frontiers in Heat and Mass Transfer 2014, 5, 1-15. https://doi.org/10.5098/hmt.5.19

Abstract

3D numerical investigations for heat transfer characteristics and flow configurations in a fin–and-oval-tube heat exchanger with V-tip pointing downstream delta winglet pairs (DDWP) are examined. The DDWPs are placed on the fin surface with pointing downstream and the oval tube row number is set at three in a staggered arrangement. The flow attack angles (θ = 15°, 30°, 45° and 60°) and the distance from V-tip to the oval tube center in transverse axis (a = 3.77, 4.77 and 5.77 mm) are investigated for Reynolds number based on hydraulic diameter, Re = 500 – 2500. The numerical results are compared with the previous experimental results and the validations of the grid system on both heat transfer and friction factor are also reported. As the results, it is found that the use of the DDWP performs higher heat transfer rate and the friction factor than the smooth fin with no DDWP for all cases. The vortex flows and the impinging jet of the flows over the oval-tube walls lead to the increase in heat transfer rate, but also increase in pressure loss. The augmentations are maximum around 1.59 and 4.4 times higher than the smooth fin for heat transfer and friction factor, respectively. In addition, the optimum thermal enhancement factor, TEF, is around 1.09 at Re = 2500, a = 5.77 mm and θ = 15°.

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