Heat Transfer Enhancement of Plate-Fin Heat Sinks with Different Types of Winglet Vortex Generators

Jin-Cherng Shyu and Jhao-Siang Jheng
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Jin-Cherng Shyu: Department of Mechanical Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 80778, Taiwan
Jhao-Siang Jheng: Department of Mechanical Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 80778, Taiwan

Energies, 2020, vol. 13, issue 19, 1-17

Abstract: Because the delta winglet in common-flow-down configuration has been recognized as an excellent type of vortex generators (VGs), this study aims to experimentally and numerically investigate the thermo-hydraulic performance of four different forms of winglet VGs featuring sweptback delta winglets in the channel flow in the range 200 < Re < 1000. Both Nusselt number and friction factor of plate-fin heat sinks having different forms of winglets, including delta winglet pair (DWP), rectangular winglet pair (RWP), swept delta winglet pair (SDWP), and swept trapezoid winglet pair (STWP), were measured in a standard wind tunnel without bypass in this study. Four rows of winglets with in-line arrangement were punched on each 10-mm-long, 0.2-mm-thick copper plate, and a total of 16 pieces of copper plates with spacing of 2 mm were fastened together to achieve the heat sink. The projected area, longitudinal and winglet tip spacing, height and angle of attack of those winglets were fixed. Besides that, three-dimensional numerical simulation was also performed in order to investigate the temperature and fluid flow over the plate-fin. The results showed that the longitudinal, common-flow-down vortices generated by the VGs augmented the heat transfer and pressure drop of the heat sink. At airflow velocity of 5 m/s, the heat transfer coefficient and pressure drop of plain plate-fin heat sink were 50.8 W/m 2 ·K and 18 Pa, respectively, while the heat transfer coefficient and the pressure drop of heat sink having SDWP were 70.4 W/m 2 ·K and 36 Pa, respectively. It was found that SDWP produced the highest thermal enhancement factor (TEF) of 1.28 at Re = 1000, followed by both RWP and STWP of similar TEF in the range 200 < Re < 1000. The TEF of DWP was the lowest and it was rapidly increased with the increase of airflow velocity.

Keywords: plate-fin; winglet; Nusselt number; friction factor; thermal enhancement factor (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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