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Experimental and Numerical Analysis for Effects of Two Inclined Baffles on Heat Transfer Augmentation in a Rectangular Duct  

Kang, Ho-Keun (Institute of Marine Industry, Gyeongsang National University)
Ahn, Soo-Whan (Department of Mechanical and Aerospace Engineering, Institute of Marine Industry, Gyeongsang National University)
Putra, Ary Bachtiar Krishna (Department of Mechanical and System Engineering, Graduate School, Gyeongsang National University)
Publication Information
Korean Journal of Air-Conditioning and Refrigeration Engineering / v.19, no.11, 2007 , pp. 751-760 More about this Journal
Abstract
Baffles enhance heat transfer by disturbing boundary layer and bulk flow, creating impingement, and increasing heat transfer surface area. This study was performed to determine how the two inclined baffles (${\alpha}=5^{\circ}$ perforated models) placed at a rectangular channel affect heat transfer and associated friction characteristics. The parametric effects of perforated baffles (3, 6 and 12 holes) and flow Reynolds number ranging from 28,900 to 61,800 on the heated target surface are explored. Comparisons of the experimental data with the numerical results by commercial code CFX 10.0 are presented. As for the investigation of heat transfer behaviors on local Nusselt number with two baffles placed at $x/D_h=0.8$ and $x/D_h=8.0$ of the edge of baffles, it is evident that the inclined perforated baffles augment overall heat transfer significantly by both jet impingement and boundary layer separation. There exists an optimum perforation density to maximize heat transfer coefficients; i.e., the average Nusselt number increases with increasing number of holes, but the friction factor decreases with an increase in the hole number placed at baffles.
Keywords
Heat transfer augmentation; Baffle; Nusselt number; Friction factor;
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