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Experimental study on thermal performances of heat sinks with cross-cut branched fins on horizontal cylinders under natural convection

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Abstract

In this study, experiments are conducted to measure the thermal resistances of heat sinks with cross-cut branched fins on horizontal cylinders. The experiments were conducted for several numbers of fin, heights of fins, and heat inputs. From the experimental data, the Nusselt number correlation for Rayleigh numbers of 190000–1000000, fin heights of 10–30 mm, and fin numbers of 9–36 is proposed. Using the suggested correlation, the fin thickness and fin number for maximizing the thermal performance are obtained. Finally, it is demonstrated that the optimal heat sink with cross-cut branched fins on a horizontal cylinder has 26 % lower thermal resistance than that of a conventional heat sink with plate fins.

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Abbreviations

A b :

Heat-sink base area without attached fins [m2]

A c :

Cross-sectional area of repeating unit in fin [m2]

A f :

Surface area of repeating unit in fin [m2]

B :

Bias error

D :

Cylinder diameter [m]

g :

Gravitational acceleration [m/s2]

H :

Fin height [m]

H 1 :

Height of stem side of branched fin [m]

H 2 :

Height of branch side of branched fin [m]

h :

Convective heat-transfer coefficient [W/m2K]

k f :

Thermal conductivity of fluid [W/mK]

k s :

Thermal conductivity of solid [W/mK]

L :

Fin length [m]

L f :

Repeating unit length [m]

N :

Fin number

N d :

Number of data

N f :

Number of repeating units

Nu :

Nusselt number

Nu cyl :

Nusselt number for horizontal cylinder

P :

Perimeter of repeating unit [m]

Pr :

Prandtl number

q :

Power input [W]

R th :

Thermal resistance [K/W]

Ra :

Rayleigh number

S :

Standard deviation

T :

Heat-sink base temperature [K]

T amb :

Ambient temperature [K]

t :

Fin thickness [m]

t 95% :

t distribution for confidence level of 95 %

U :

Uncertainty

α :

Angle between tributary branches [°]

α f :

Thermal diffusivity of fluid [m2/s]

β f :

Volume expansion coefficient of fluid [1/K]

η :

Fin efficiency

v f :

Kinematic viscosity of fluid [m2/s]

T :

Temperature [K]

q :

Power input [W]

R th :

Thermal resistance [K/W]

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Acknowledgments

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. 2020R1F1A1070142).

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Authors and Affiliations

  1. Department of Mechanical Engineering, Ajou University, Suwon-si, Gyeonggi-do, 16499, Korea

    Donghyuk Kim & Dong-Kwon Kim

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  1. Donghyuk Kim
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  2. Dong-Kwon Kim
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Correspondence to Dong-Kwon Kim.

Additional information

Donghyuk Kim is a Ph.D. student in the Department of Mechanical Engineering at Ajou University, Korea. His research interests include heat transfer, photothermal therapy, and air conditioning.

Dong-Kwon Kim is a Professor in the Department of Mechanical Engineering at Ajou University, Korea. His current research interests include various air-cooled heat sinks and deep learning-based design of thermal systems.

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Kim, D., Kim, DK. Experimental study on thermal performances of heat sinks with cross-cut branched fins on horizontal cylinders under natural convection. J Mech Sci Technol 35, 3743–3751 (2021). https://doi.org/10.1007/s12206-021-0743-5

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  • DOI: https://doi.org/10.1007/s12206-021-0743-5

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