Abstract
In this paper, an experimental study investigating the effect of the geometrical shape of the circular and rectangular pin fins on the heat transfer performance and the boiling phenomenon is presented. A pool boiling experiment in the HFE-7100 dielectric working fluid under atmospheric pressure was conducted. Boiling curves and boiling heat transfer coefficients of different test cases were plotted to evaluate the heat transfer performance as well as the captured images of the boiling phenomenon on the test samples. Two quantities, flow resistance and wetted perimeter, were calculated to understand the behaviour of the boiling physics due to variation of fin geometrical shape and, hence, their effect on the heat transfer performance. It was found that the cooling performance of the rectangular pin fins was higher than that of the circular pin fins, despite having a slightly higher flow resistance of 4% and 7%, respectively. This is believed to be the result of the longer wetted perimeter up to 27%, whereby the nucleation site has a higher probability of generating more bubbles in the same boiling surface area. For the tested modified boiling surface with 196 and 144 pin fins, the average heat transfer performances were found to have differences of up to 3.54 and 1.58 times larger, respectively.
Highlights
In addition to the natural convection of the single-phase liquid, the cooling process is enhanced by the process of bubble evaporation and surface rewetting, which results in a higher heat transfer coefficient [1]
Several industrial applications rely on boiling heat transfer to achieve high heat flux removal for their applications, for instance, nuclear power plants [3], cryogenic applications [4], and server cooling [5]
Two samples are constituted of circular pin fins, whilst the two others are constituted of rectangular pin fins, as shown in 2 and 1 mm, respecFigure
Summary
Boiling heat transfer has been demonstrated to be an effective cooling mechanism. It provides an excellent heat transfer coefficient due to the chaotic movement of the bubble. Rainey and You [14] reported the effect of pin fin height on the heat transfer enhancement. With the fin wide and spacing of 1 mm, it was height on the heat transfer enhancement. With the fin wide and spacing of 1 mm, it was demonstrated that the heat transfer was significantly improved as the height increased. Kelin and Westwater [16] investigated the effect of fin horizontal configuration on the heat transfer performance. More comprehensive studies exploring the instance, effect of bubble have been carried out on the micro-structured surface. The effect of pin fin geometrical configuration has been widely investigated, albeit the exact sizing varies based on many parameters. Energies 2022, 15, 1847 transfer performance between circular and rectangular macro pin fins.
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