A numerical investigation on the effect of shape-size-number of drills on heat transfer characteristics of a circular pin fin

An increased circuit density with digitalization and miniaturization demands a compact design for the heatsink with enhanced heat dissipation capabilities. The performance of an active air-cooled pin fin heatsink depends on the geometry of the fin, which should offer more surface area for the given volume (Compact). Providing drills in a pin fin offers a more convective surface with conduction loss, and is function of place, size, shape, and number of drills. So, this investigation is focused on studying the heat transfer characteristics of a drilled pin fin of length L and diameter D to elucidate the effect of (1) shapes; circular, elliptical, and triangular, (2) locations; L/4, L/2, and 3 L/4, (3) sizes between 0.3D and 0.5D, and (4) number; 1, 2, 4, and 6 of drills on maximum fin temperature (<i>T_max</i>) and convective resistance for differential heat inputs in different convection environments. It throws light on the possible replacement of solid fins with drilled fins for enhanced heat dissipation. It offers either more heat transfer, for the given volume with reduced weight, or decreased volume for the mandated heat load. The results demonstrated that the drill location has a mere or insignificant effect on T_max. For all the shapes considered in the study, T_max first decreases with the enlarging drill size reaches it’s minimum at 0.5D, and increases after that. The increased number of drills from 1 to 6, of size 0.5D, brings down the T_max by 20%, 20%, and 25% with circular, elliptical, and triangular drills, respectively.

伴随数字化与微型化发展，电路集成度不断提升，散热器亟需兼顾紧凑化设计与强化散热性能的双重要求。主动风冷针翅散热器的散热性能取决于翅片的几何结构，在限定体积下，翅片需具备更大的换热表面积以实现紧凑化设计。在针翅上开设钻孔虽会产生一定导热损耗，但可获得更大的对流换热表面积，且该效果取决于钻孔的位置、尺寸、形状与数量。因此，本研究聚焦于长度为L、直径为D的钻孔针翅的传热特性，旨在阐明钻孔参数对翅片最高温度（T_max）与对流热阻的影响规律，其中钻孔参数包括：(1) 形状：圆形、椭圆形与三角形；(2) 位置：L/4、L/2与3L/4；(3) 尺寸：0.3D至0.5D区间；(4) 数量：1、2、4与6个，研究场景涵盖不同对流环境下的变热输入工况。本研究可为采用钻孔针翅替代实体针翅以强化散热提供理论参考。钻孔针翅方案可在限定体积下实现更高换热量且降低翅片重量，或在满足指定热负荷的前提下缩小散热器体积。研究结果表明，钻孔位置对T_max的影响极小，可忽略不计。针对本研究中所有的钻孔形状，T_max均随钻孔尺寸增大先降低，在0.5D时达到最小值，随后随尺寸继续增大而升高。当钻孔尺寸为0.5D时，将钻孔数量从1个增加至6个，可使圆形、椭圆形与三角形钻孔针翅的T_max分别降低20%、20%与25%。