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Research Papers: Forced Convection

Forced Convection Heat Transfer Enhancement by Porous Pin Fins in Rectangular Channels

[+] Author and Article Information
Jian Yang, Min Zeng

State Key Laboratory of Multiphase Flow in Power Engineering, School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China

Qiuwang Wang1

State Key Laboratory of Multiphase Flow in Power Engineering, School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, Chinawangqw@mail.xjtu.edu.cn

Akira Nakayama

Department of Mechanical Engineering, Shizuoka University, 3-5-1 Johoku, Hamamatsu 432-8561, Japan

1

Corresponding author.

J. Heat Transfer 132(5), 051702 (Mar 05, 2010) (8 pages) doi:10.1115/1.4000708 History: Received January 08, 2009; Revised November 07, 2009; Published March 05, 2010; Online March 05, 2010

The forced convective heat transfer in three-dimensional porous pin fin channels is numerically studied in this paper. The Forchheimer–Brinkman extended Darcy model and two-equation energy model are adopted to describe the flow and heat transfer in porous media. Air and water are employed as the cold fluids and the effects of Reynolds number (Re), pore density (PPI) and pin fin form are studied in detail. The results show that, with proper selection of physical parameters, significant heat transfer enhancements and pressure drop reductions can be achieved simultaneously with porous pin fins and the overall heat transfer performances in porous pin fin channels are much better than those in traditional solid pin fin channels. The effects of pore density are significant. As PPI increases, the pressure drops and heat fluxes in porous pin fin channels increase while the overall heat transfer efficiencies decrease and the maximal overall heat transfer efficiencies are obtained at PPI=20 for both air and water cases. Furthermore, the effects of pin fin form are also remarkable. With the same physical parameters, the overall heat transfer efficiencies in the long elliptic porous pin fin channels are the highest while they are the lowest in the short elliptic porous pin fin channels.

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Copyright © 2010 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

Physical model: (a) porous pin fin heat sink and (b) representative computational domain

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Figure 2

Different forms of porous pin fin cross-section: (a) circular form, (b) cubic form, (c) long elliptic form, and (d) short elliptic form

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Figure 3

Physical models for model validation: (a) 2D physical model reported in Ref. 5 and (b) 3D physical model used for present computation (based on (a))

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Figure 4

Comparison of average Nusselt number of each heater with Ref. 5

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Figure 5

Temperature distributions in solid and circular porous pin fin channels (ϕ=0.9, PPI=30, Re=1000): (a) solid pin fin channel with air, (b) porous pin fin channel with air, (c) solid pin fin channel with water, and (d) porous pin fin channel with water

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Figure 6

Velocity vector distributions in solid and porous pin fin channels (ϕ=0.9, PPI=30, Re=1000): (a) solid pin fin channel (air: y=5 mm), (b) porous pin fin channel (air: y=5 mm), (c) solid pin fin channel (water: y=0.5 mm), and (d) porous pin fin channel (water: y=0.5 mm)

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Figure 7

Variations in pressure drop, hot wall heat flux, overall heat transfer efficiency, and heat transfer performance ratio with Re in solid and porous pin fin channels (ϕ=0.9, PPI=30): (a) pressure drop and hot wall heat flux and (b) overall heat transfer efficiency and heat transfer performance ratio

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Figure 8

Variations in pressure drop, hot wall heat flux, and overall heat transfer efficiency with pore density (ϕ=0.9, Re=2291)

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Figure 9

Temperature distributions in different porous pin fin channels with air (ϕ=0.9, PPI=40, Pr=0.7, Re=1000): (a) circular pin fin channel, (b) cubic pin fin channel, (c) long elliptic pin fin channel, and (d) short elliptic pin fin channel

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Figure 10

Temperature distributions in different porous pin fin channels with water (ϕ=0.9, PPI=40, Pr=3.9, Re=1000) (a) circular pin fin channel, (b) cubic pin fin channel, (c) long elliptic pin fin channel, and (d) short elliptic pin fin channel

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Figure 11

Variations in pressure drop, hot wall heat flux and overall heat transfer efficiency with Re in different porous pin fin channels (ϕ=0.9, PPI=40, Pr=0.7)

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Figure 12

Variations in pressure drop, hot wall heat flux and overall heat transfer efficiency with Re in different porous pin fin channels (ϕ=0.9, PPI=40, Pr=3.9)

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