分-合式微通道流动传热性能数值模拟

针对矩形微通道进出口压降大、温度分布不均匀,以及分形微通道受到分形维数和分支数限制适用范围较窄的问题,结合矩形微通道和分形微通道的优势设计一种分-合式微通道散热器。使用Fluent软件对散热过程进行数值模拟,研究微通道内分支倾斜角度变化对流动和传热性能的影响。结果表明,在100 W/cm²的热流密度下,Re为970、分支倾斜角度为90°时,分-合式微通道平均温度降低了11.9 K,最高温度降低了14.2 K,Nu增加了85.7%,整体传热性能(PEC)也最佳,达到1.44。分支的引入可以增加微通道内部换热面积,同时形成新的边界层,在分支内侧产生漩涡,有效提高了微通道散热器的传热性能,为微通道的优化设计提供了新的理论依据。

Numerical simulation of flow and heat transfer performance in branch and combined-branch microchannel

The pressure drop at the inlet and outlet of rectangular microchannel is large, and the temperature distribution is uneven; Fractal microchannel is limited by fractal dimension and the number of branches, so its application scope is narrow. A branch and combined-branch microchannel heat sink was designed by combining the advantages of rectangular microchannel and fractal microchannel, and Fluent software was used to numerically simulate its heat dissipation process to study the flow and heat transfer performance when the branch tilt angle inside the microchannel changes. The results show that at the heat flow of 100 W/cm2, when the Re is 970 and the branch tilt angle is 90°, the average temperature of the branch and combined-branch microchannel decreases by 119 K, the maximum temperature decreases by 142 K, the Nu increases by 857%, and the performance evaluation criterion (PEC) is also the best by reaching 144. The introduction of branches can increase the heat transfer area inside the microchannel, form a new boundary layer, and generate vortices at the inner side of the branch, effectively improving the heat transfer performance of the microchannel heat sinks, which provides new theoretical basis for optimizing the design of microchannels.