Research Papers: Heat Transfer Enhancement

Radiant Fin Performance Using Fractal-like Geometries

[+] Author and Article Information
Daniel Dannelley

Department of Mechanical Engineering,
The University of Alabama,
Box 870276,
Tuscaloosa, AL 35487-0276
e-mail: danne001@crimson.ua.edu

John Baker

Department of Aerospace Engineering
and Mechanics,
The University of Alabama,
Box 870280,
Tuscaloosa, AL 35487-0280
e-mail: john.baker@eng.ua.edu

Contributed by the Heat Transfer Division of ASME for publication in the Journal of Heat Transfer. Manuscript received July 20, 2012; final manuscript received February 26, 2013; published online July 18, 2013. Assoc. Editor: Bruce L. Drolen.

J. Heat Transfer 135(8), 081902 (Jul 18, 2013) (8 pages) Paper No: HT-12-1384; doi: 10.1115/1.4023883 History: Received July 20, 2012; Revised February 26, 2013

The results of a computational study into the thermal performance of thermally radiating fractal-like fins are presented. Previous experimental studies have shown that fractal patterns increase the heat transfer surface area while simultaneously reducing mass. Two fractal patterns were used for comparison, the modified Koch snowflake and the Sierpinski carpet. For an isothermal base fin radiating to free space, the fin effectiveness and fin efficiency are presented for the zeroth and first four fractal iterations in order to quantify the performance. Emissivity, width/thickness ratio, base temperature, and fin material were varied to better understand their impact on the performance of fractal-like fins. Based upon the observed results, fractal-like fins greatly improve the fin effectiveness per unit mass. In certain cases, fin effectiveness per unit mass was found to increase by up to 46%. As the cost of access to space is significant, this reduction in mass could lead to savings for spacecraft thermal management applications.

Copyright © 2013 by ASME
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Fig. 4

Area/initial area versus iteration

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Fig. 3

Isometric views, zeroth iteration, w = 10.16 cm and t = 0.3175 cm

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Fig. 2

Sierpinski carpet (top) and modified Koch snowflake (bottom)

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Fig. 1

Computational model validation

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Fig. 5

Fin effectiveness/mass, variable fractal pattern

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Fig. 6

Fin effectiveness, variable emissivity

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Fig. 7

Fin effectiveness/mass, variable emissivity

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Fig. 8

Fin efficiency, variable emissivity

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Fig. 9

Fin effectiveness, variable width/thickness ratio

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Fig. 10

Fin effectiveness/mass, variable width/thickness ratio

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Fig. 11

Fin efficiency, variable width/thickness ratio

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Fig. 12

Fin effectiveness/mass, variable Tb

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Fig. 13

Fin effectiveness/mass, variable material

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Fig. 14

Fin effectiveness correlation



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