Abstract:

In order to achieve high heat flux electronic device cooling, HFE-7100 was used as the working fluid to conduct an experimental study on the flow boiling characteristics of three wedge-shaped manifold microchannels and compared them with conventional rectangular manifold microchannels. The effects of two manifold configurations and two surface enhancement structures on the boiling heat transfer coefficients, critical heat fluxes and flow pressure drops under different flow rates and inlet subcooling are discussed. The experimental results show that the wedge-shaped manifold can promote the transition of flow pattern from churn flow to annular flow, and increase the fluid transport efficiency and vapor discharge efficiency, thus improving the heat transfer performance while reducing the flow pressure drop. Compared with the micro-pin-fin enhancement structure, the porous surface processed by femtosecond laser provides a simple and convenient method to enhance the boiling heat transfer, which can greatly expand the heat transfer surface, provide a large number of nucleation sites, and significantly increase the CHF. Combining the wedge-shaped manifold with porous microchannels, the average two-phase heat transfer coefficient of the manifold microchannels is increased by 21.6%, the critical heat flux is increased by 30.4%, and the two-phase pressure drop is reduced by 12.7%, which realizes a significant improvement in the comprehensive performance of manifold microchannel heat sinks.

Key words: microchannel, flow boiling, heat transfer, two-phase flow, comprehensive performance

摘要：

为实现高热通量电子器件冷却，以HFE-7100作为工作流体，对3种楔形歧管微通道流动沸腾特性进行实验研究，并与常规的矩形歧管微通道进行对比，讨论了不同流量和过冷度条件下两种歧管几何形状和两种表面强化结构对沸腾传热系数、临界热通量和流动压降的影响。结果表明：楔形歧管结构能够促进流型由搅拌流转变为环状流，并提高流体输送效率与蒸汽排放效率，从而在改善换热性能的同时降低流动压降。与微针翅结构相比，采用激光烧蚀的多孔表面提供了一种简单便捷的强化沸腾换热的方法，能够极大地拓展换热表面，提供大量的成核位点，显著提高临界热通量（CHF）。将楔形歧管供液结构与多孔微通道相结合，歧管微通道平均两相传热系数提高了21.6%，临界热通量提高了30.4%，两相压降降低了12.7%，实现微通道散热器综合性能的显著提升。

关键词: 微通道, 流动沸腾, 换热, 两相流, 综合性能