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RESEARCH PAPERS

Study of Flow and Heat Transfer Characteristics in Asymmetrically Heated Sintered Porous Heat Sinks With Periodical Baffles

[+] Author and Article Information
Tzer-Ming Jeng

Department of Mechanical Engineering,  Air Force Institute of Technology, GangShan 820, Taiwan, R.O.C.

Sheng-Chung Tzeng1

Department of Mechanical Engineering,  Chienkuo Technology University, Changhua 500, Taiwan, R.O.C.tsc@ctu.edu.tw

1

Corresponding author.

J. Electron. Packag 128(3), 226-235 (Aug 18, 2005) (10 pages) doi:10.1115/1.2229220 History: Received February 06, 2005; Revised August 18, 2005

Abstract

This work numerically examined the mechanism of heat transfer in a sintered porous heat sink with baffles. A channel filled with the sintered porous heat sink was asymmetrically heated and metallic baffles were periodically mounted on the heated surface. The fluid medium was air. The results indicate that no recirculation occurred between baffles. The metallic baffle obtained heat from the heated surface by conduction directly from the heated surface and indirectly through the porous media. It dissipated heat to the fluid that passed over the zone above the baffle. The Nusselt numbers in the cases with baffles exceeded those in cases without a baffle. The enhancement in the average Nusselt numbers of sintered porous heat sinks with baffles increased as the Reynolds number (Re) declined; the baffle height $(h∕H)$ increased; the baffle length $(w∕H)$ increased, or the baffle pitch $(XL)$ decreased. However, at $Re=500$, the average Nusselt number in the case with $h∕H=0.3$ was higher than those with $h∕H=0.7$, 0.5, and 0.1. Additionally, the minimum enhancement appeared at around $Re=3000$ for various $h∕H$, $w∕H$, and $XL$. For the cases with $h∕H⩽0.3$ and various $w∕H$ as well as $XL$, at $Re>3000$, sintered porous heat sinks with baffles insignificantly improved heat transfer.

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Figures

Figure 1

Schematic diagram of the porous channel with periodical baffles

Figure 2

Schematic diagram of numerical domain with boundary conditions

Figure 3

Experimental apparatus

Figure 4

The photo of test specimen and positions of thermocouples: (a) photograph of test specimen and (b) positions of thermocouples

Figure 5

Comparison with experimental data: (a) without baffles and (b) with baffles

Figure 6

Contours of stream line for h∕H=0.3, w∕H=0.4, XL=2.50(n=5), and Re=2000

Figure 7

Velocity vector for Re=2000: (a) h∕H=0.3, w∕H=0.2, XL=5.25(n=5), (b) h∕H=0.3, w∕H=0.4, XL=2.50(n=5), and (c) h∕H=0.7, w∕H=0.4, XL=2.50(n=5)

Figure 8

Contours of temperature for h∕H=0.3, w∕H=0.4, XL=2.50(n=5), and Re=2000: (a) solid temperature and (b) fluid temperature

Figure 9

Local Nusselt number distributions in the peripheral direction of the baffle surface for h∕H=0.3, w∕H=0.4, XL=2.5(n=5), and Re=2000

Figure 10

Effect of baffle height on local Nusselt number distributions in the x-direction

Figure 11

Effect of baffle length on local Nusselt number distributions in the x-direction

Figure 12

Effect of baffle pitch on local Nusselt number distributions in the x-direction

Figure 13

Enhancements of average Nusselt number in sintered heat sinks with baffles: (a) effect of baffle height, (b) effect of baffle length, and (c) effect of baffle pitch

Figure 14

Correlation between average Nusselt number and Reynolds number for the case without baffles

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