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Research Papers: Micro/Nanoscale Heat Transfer

Investigations on the Influence of Flow Migration on Flow and Heat Transfer in Oblique Fin Microchannel Array

[+] Author and Article Information
Nasi Mou

Department of Mechanical Engineering,
Faculty of Engineering,
National University of Singapore,
9 Engineering Drive 1,
Singapore 117576, Singapore
e-mail: mounasi@nus.edu.sg

Yong Jiun Lee

Department of Mechanical Engineering,
Faculty of Engineering,
National University of Singapore,
9 Engineering Drive 1,
Singapore 117576, Singapore
e-mail: yongjiun.lee@cadit.com.sg

Poh Seng Lee

Department of Mechanical Engineering,
Faculty of Engineering,
National University of Singapore,
9 Engineering Drive 1,
Singapore 117576, Singapore
e-mail: mpelps@nus.edu.sg

Pawan K. Singh

Department of Mechanical Engineering,
Faculty of Engineering,
National University of Singapore,
9 Engineering Drive 1,
Singapore 117576, Singapore
e-mail: mpepks@nus.edu.sg

Saif A. Khan

Department of Chemical and
Biomolecular Engineering,
Faculty of Engineering,
National University of Singapore,
9 Engineering Drive 1,
Singapore 117575, Singapore
e-mail: saifkhan@nus.edu.sg

1Corresponding author.

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF HEAT TRANSFER. Manuscript received April 5, 2016; final manuscript received April 29, 2016; published online June 7, 2016. Editor: Portonovo S. Ayyaswamy.

J. Heat Transfer 138(10), 102403 (Jun 07, 2016) (13 pages) Paper No: HT-16-1173; doi: 10.1115/1.4033540 History: Received April 05, 2016; Revised April 29, 2016

In order to scrutinize the coolant mass distribution and its effect to the heat transfer in oblique fin microchannel array, extensive numerical studies are performed on planar oblique fin configuration. Full-domain simulations using common-flow down (CFD) approach are employed to provide better insights into the flow distribution, flow stability, and heat transfer performance at a global level. The flow field and temperature profile analysis shows that nonuniform coolant distribution and coolant migration occur in the oblique fin microchannel, and the heat transfer performance for both edges of the heat sink is affected due to changing secondary flow rate. However, the flow migration does not affect the local coolant velocity and temperature profiles significantly in the middle region (0.2 < Z′ < 0.8). Meanwhile, it is also found that Reynolds number affects the coolant migration, the stability of the fluid flow, and heat transfer performance significantly. Higher Reynolds number increases the percentage of secondary flow rate and, hence, enhances the heat transfer for fin surfaces in secondary channels.

Copyright © 2016 by ASME
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References

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Figures

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Fig. 1

(a) Three-dimensional computational domain of oblique fin microchannel heat sink, (b) 2D schematic of oblique fin microchannel array and dimensions, and (c) local coordinate system of an oblique unit

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Fig. 2

(a) Total pressure drop comparisons, (b) average Nusselt numbers comparisons between numerical results and experimental data for the oblique fin microchannel heat sink, and (c) average Nusselt numbers comparisons by eliminating the thermal area close to the entry region till X′ = 0.2

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Fig. 3

Coolant mass flow rate distribution in the main channels of oblique fin microchannel heat sink when Re = 250

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Fig. 4

Coolant mass flow rate distribution in the oblique channels of oblique fin microchannel heat sink when Re = 250

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Fig. 5

Coolant (a) axial velocity and (b) temperature profiles in the main channels at X′ = 0.01, Y′ = 0.5, when Re = 250

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Fig. 6

Coolant (a) axial velocity and (b) temperature profiles in the main channels at X′ = 0.20, Y′ = 0.5, when Re = 250

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Fig. 7

Coolant (a) axial velocity and (b) temperature profiles in the oblique channels at X′ = 0.01, Y′ = 0.5 (mid-depth plane), when Re = 250

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Fig. 8

Coolant (a) axial velocity and (b) temperature profiles in the oblique channels at X′ = 0.20, Y′ = 0.5, when Re = 250

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Fig. 9

Variation of (a) axial velocity profiles when Re = 250, (b) water temperature profiles when Re = 250, (c) axial velocity profiles when Re = 660, and (d) water temperature profiles when Re = 660 in the mid-depth plane of channel within the oblique fin microchannel heat sink at different time steps

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Fig. 10

Coolant mass flow rate distribution in the main channel at different streamwise distances: (a) X′ = 0.01, (b) X′ = 0.39, and (c) X′ = 0.81, when Re = 660

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Fig. 11

Coolant mass flow rate distribution in the oblique channel at different streamwise distances: (a) X′ = 0.39 and (b) X′ = 0.81, when Re = 660

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Fig. 12

Temperature contour (in  °C) at the bottom wall of heat sink for Re = 250

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Fig. 13

Average heater wall temperature profiles in the oblique fin microchannel heat sink when Re = 250

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Fig. 14

Local heat transfer coefficient profiles of oblique fin microchannel heat sink when Re = 250

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Fig. 15

Local coolant temperature in the oblique fin microchannel heat sink when Re = 250

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Fig. 16

Temperature contour (in  °C) at the bottom wall of silicon-based oblique fin microchannel heat sink at Re = 660

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Fig. 17

Area-weighted average heater surface temperature when Re = 660

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Fig. 18

Local heat transfer coefficients of oblique fin microchannel heat sink when Re = 660

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Fig. 19

Comparison of heat transfer rate between fin surfaces for (a) Re = 250 and (b) Re = 660

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