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RESEARCH PAPERS

Flow Structure and Enhanced Heat Transfer in Channel Flow With Dimpled Surfaces: Application to Heat Sinks in Microelectronic Cooling

[+] Author and Article Information
Carlos Silva

Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843-3123cas@tamu.edu

Egidio Marotta, Leroy Fletcher

Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843-3123

J. Electron. Packag 129(2), 157-166 (Jul 03, 2006) (10 pages) doi:10.1115/1.2721087 History: Received November 22, 2005; Revised July 03, 2006

The use of dimple technology for improvement in friction factors and enhancement of heat transfer has been attracting the attention of many scientists and engineers. Numerical and experimental studies have shown there is a positive improvement (two-fold on average) in Nusselt number when dimpled surfaces are compared to flat plates, and this improvement is achieved with pressure drop penalties that are small when compared to other more intrusive types of turbulence promoters. When arrays of specific dimple geometry are used, pressure drop penalties are roughly equivalent to the heat transfer improvement. This, at least theoretically, will enable the design of smaller heat transfer devices such as heat sinks, which are especially appealing in those applications where size is an important design factor. A literature review of numerical modeling and experiments on flow over dimpled surfaces was performed, and key parameters and flow structure were identified and summarized. With these premises, a numerical model was developed. The model was validated with published experimental data from selected papers and fine tuned for channel flow within the laminar flow regime. Subsequently, the model was employed for a specific application to heat sinks for microelectronic cooling. This paper, then, provides a comparative evaluation of dimple technology for improving heat transfer in microelectronic systems.

Copyright © 2007 by American Society of Mechanical Engineers
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References

Figures

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Figure 4

Relative friction factor (with error bars) as a function of Reynolds number

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Figure 5

Relative friction factor as a function of relative Nusselt number (with error bars)

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Figure 6

3D plot of friction factor, Nusselt, and Reynolds number

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Figure 7

3D plot of friction factor, Nusselt, and Reynolds number

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Figure 8

Dimple geometry and array from Mahmood (2). Dimension in mm: (a) symmetry plane mesh; (b) 3D view of test surface and symmetry plane

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Figure 9

Numerical model mesh: (a) refined dimple mesh; (b) mesh distribution over test surface

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Figure 10

Numerical model mesh

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Figure 11

Nu∕Nu0, ReH=10,000, numerical model: (a)Nu∕Nu0 (ten contours); (b)Nu∕Nu0 (40 contours)

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Figure 12

Nu∕Nu0, ReH=10,200, from Mahmood (2)

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Figure 13

Local Nu∕Nu0 comparison between numerical model (circles) and data from Mahmood (crosses). Bottom lines correspond to dimple rows 10 and 12. X axis (X∕D coordinate) corresponds to Fig. 1.

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Figure 14

(a) Mesh distribution over improved design; and (b) 3D view of test surface and symmetry plane

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Figure 15

Nu∕Nu0, ReH=10,000, improved model. Area displayed correspond to the same coordinates as Figs.  1212. (a)Nu∕Nu0 (ten contours); and (b)Nu∕Nu0 (40 contours)

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Figure 16

Local Nu∕Nu0 comparison between original and improved model. Lines show dimple position in original (solid) and improved (dotted) models.

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Figure 1

Effect of dimples on sphere’s form drag (1): smooth ball; wire hoop ball (wire added to simulate dimples)

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Figure 2

Vortex structure over dimples in a flat wall (from Mahmood (2))

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Figure 3

Relative Nusselt number (with error bars) as a function of Reynolds number

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