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Research Papers

Optimum Fin Parameters of Radial Heat Sinks Subjected to Natural Convection

[+] Author and Article Information
S. Manna

Department of Mechanical Engineering,
Indian Institute of Technology,
Dhanbad, Jharkhand, India

S. K. Ghosh

Department of Mechanical Engineering,
Indian Institute of Technology,
Dhanbad, Jharkhand, India
e-mail: subrata@iitism.ac.in

S. C. Haldar

Department of Mechanical Engineering,
Haldia Institute of Technology,
Purba Medinipur, West Bengal, India

Contributed by the Heat Transfer Division of ASME for publication in the Journal of Thermal Science and Engineering Applications. Manuscript received November 22, 2018; final manuscript received February 27, 2019; published online March 21, 2019. Assoc. Editor: Nesrin Ozalp.

J. Thermal Sci. Eng. Appl 11(5), 051006 (Mar 21, 2019) (8 pages) Paper No: TSEA-18-1595; doi: 10.1115/1.4043091 History: Received November 22, 2018; Accepted February 27, 2019

Free convection from an upward facing radial heat sink with fins at an equal angular gap attached to an isothermal base has been investigated numerically. The governing equations in primitive variables were changed to vorticity-vector potential formulation, and an in-house code was developed using finite difference technique. To close the computational domain, two pseudo boundaries were considered. Length, height, and number of fins strongly influence the rate of heat transfer while the fin thickness has a marginal role. As the fin length increases, the rate of heat transfer first increases and then remains almost unaffected. However, the active length of the fins depends on the strength of buoyancy. Heat transfer continuously increases with fin height but with diminishing effect. Adding more number of fins has two opposing effects. It provides more surface area for convection, but at the same time, the induced air is unable to reach the interior of the heat sink making the inner portion of the fins inoperative. As a result of these two opposing influences, heat transfer increases in the beginning and then decreases as more fins are added. This article suggests various fin parameters to achieve maximum cooling. In addition, one can estimate the rate of cooling to be achieved by any radial heat sink.

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References

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Figures

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Fig. 1

Geometry of the chosen heat sink

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Fig. 2

Computational domain together with the coordinate system

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Fig. 6

Variation of heat transfer from fins with height at different Gr

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Fig. 7

Variation of heat transfer from base plate with fin height at different Gr

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Fig. 3

Nu versus Ra for free convection from an upward facing smooth circular plate

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Fig. 4

Variation of dQ/dr with radius for smooth circular plate

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Fig. 5

(a) Velocity vectors for Gr = 106, N = 20, H = 0.6, and L = 1.0. (b) Isotherms at θ = 0 for Gr = 106, N = 30, H = 0.6, and L = 1.0

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Fig. 10

Heat transfer from base plate with number of fins at different fin height

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Fig. 8

Variation of heat transfer from fins with length at different Gr

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Fig. 9

Variation of heat transfer from fins with number of fins at different fin height

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Fig. 11

Variation of base temperature over that of ambient with heat flux (+, experimental [6]; dashed line, numerical [6]; solid line, present)

Tables

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