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ARTICLE

THERMAL PERFORMANCE ASSESSMENT IN A CIRCULAR TUBE FITTED WITH VARIOUS SIZES OF MODIFIED V-BAFFLES: A NUMERICAL INVESTIGATION

by

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, School of Engineering, King Mongkut’s Institute of Technology Ladkrabang, Bangkok 10520, Thailand
* Corresponding author. Email: withada.je@kmitl.ac.th

Frontiers in Heat and Mass Transfer 2021, 16, 1-16. https://doi.org/10.5098/hmt.16.17

Abstract

This research reports numerical examinations on fluid flow, heat transfer behavior and thermal performance analysis in a circular tube equipped with modified V-baffles (CTMVB). The modified V-baffle (MVB) is a combination vortex generator between V-baffles/V-orifices which are placed on the tube wall and V-baffles which are inserted at the core of the tested tube. The MVB height is separated into two parts; b1 represents the MVB height on the tube wall, while b2 represents the MVB height at the core of the tested round tube. The MVB height to tube diameter ratios, b/D, are adjusted; b₁/D = 0.05, 0.1, 0.15 and 0.2, and b₂/D = 0.025, 0.05, 0.075 and 0.1. The Reynolds numbers of about 100 – 2000 (laminar regime) are considered. The flow directions in the tested section; V-tip directing downstream and V-tip directing upstream, are discussed. The flow attack angles for the MVB, α, of about 20o and 30o are compared. The finite volume method with SIMPLE algorithm (a commercial code) is opted to analyze the present investigation. The computational domain of the CTMVB is validated (grid independence and smooth tube validations). It is found that the MVB generates many vortex cores in the tested section. The vortex flows near the tube wall disrupt thermal boundary layer, while the vortex flows at the center of the tube help superior fluid blending. The disturbed thermal boundary layer and the better fluid blending are main two causes for heat transfer augmentation. In addition, the best thermal enhancement factor of the CTMVB is found to be around 3.92.

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