Numerical studies have been performed to analyze the fluid flow and heat transfer characteristics of nine microchannel heat sinks (MCHS) with different shapes and different arrangements of the ribs and cavities on the sidewalls, using three common shapes (square, triangle, and circular) of ribs or cavities as the basic structure in this work. The boundary conditions, governing equations, friction factor ( f ), Nusselt number (Nu), and performance evaluation criteria ( ξ ) were considered to determine which design was the best in terms of the heat transfer, the pressure drop, and the overall performance. It was observed that no matter how the circular ribs or cavities were arranged, its heat sink performance was better than the other two shapes for Reynolds number of 200–1000. Therefore, circular ribs or cavities can be considered as the best structure to improve the performance of MCHS. In addition, the heat sink performance of the microchannel heat sink with symmetrical circular ribs (MCHS-SCR) was improved by 31.2 % compared with the conventional microchannel heat sink at Re = 667. This was because in addition to the formation of transverse vortices in the channel, four symmetrical and reverse longitudinal vortices are formed to improve the mixing efficiency of the central fluid (low temperature) and the near-wall fluid (high temperature). Then, as the Reynolds number increases, the heat sink performance of MCHS-SCR dropped sharply. The heat sink performance of microchannel heat sinks with staggered ribs and cavities (MCHS-SCRC, MCHS-STRC, and MCHS-SSRC) exceeded that of MCHS-SCR. This indicated that the microchannel heat sink with staggered ribs and cavities was more suitable for high Reynolds number (Re > 800).

中文翻译：

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不同结构微通道散热器中流体流动与传热的三维仿真分析

使用三种常见形状（方形、三角形和圆形）的不同形状和侧壁上的肋和腔的不同排列的九个微通道散热器（MCHS）的流体流动和传热特性进行了数值研究。肋骨或空腔作为这项工作的基本结构。考虑边界条件、控制方程、摩擦系数 ( f )、努塞尔数 (Nu) 和性能评估标准 ( ξ ) 来确定哪种设计在传热、压降和整体性能方面最好. 观察到无论圆形肋或腔如何排列，其散热性能均优于其他两种形状，雷诺数为 200-1000。所以，圆形肋条或空腔可以被认为是提高MCHS性能的最佳结构。此外，在 Re = 667 时，具有对称圆肋的微通道散热器（MCHS-SCR）的散热性能比传统的微通道散热器提高了 31.2%。通道内形成四个对称反向的纵向涡流，提高中心流体（低温）和近壁流体（高温）的混合效率。然后，随着雷诺数的增加，MCHS-SCR 的散热性能急剧下降。具有交错肋和腔的微通道散热器（MCHS-SCRC、MCHS-STRC和MCHS-SSRC）的散热器性能超过了MCHS-SCR。