Abstract During flow boiling in microchannels, the physics of a bubble is closely related to the heat transfer performance of different hydrophobic patterns. However, the heat transfer properties of various patterns are yet to be investigated. In this study, we conducted a numerical investigation into bubble coalescence characteristics and heat transfer performance of three patterns, namely crosswise, parallel, and dotted patterns, for flow boiling in a microchannel, and evaluated the influence of the hydrophobic area fraction for each pattern. In the transport equation, we employed a mass transfer model based on a two-phase mixture flow for the vaporization and condensation processes. In addition, we used the volume-of-fluid method to track the dispersed phase's interface using the local volume fraction. Although the parallel pattern at low mass flux facilitating bubble movement exhibited a good heat transfer performance, the dotted pattern displayed a better performance at high mass fluxes due to its higher nucleation site density. Additionally, very wide or narrow hydrophobic areas are unsuitable for heat transfer. Narrow areas limit bubble nucleation. A hydrophobic area fraction of 0.165 for the crossed pattern and of 0.32 for the parallel and dotted pattern produced the best heat transfer performances.

中文翻译：

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微通道中异质润湿表面气泡流动增强流动沸腾

摘要 在微通道内流动沸腾过程中，气泡的物理特性与不同疏水模式的传热性能密切相关。然而，各种图案的传热性能还有待研究。在本研究中，我们对微通道中流动沸腾的三种模式（即横向、平行和点状模式）的气泡聚结特性和传热性能进行了数值研究，并评估了每种模式的疏水面积分数的影响。在传输方程中，我们采用了基于汽化和冷凝过程的两相混合物流的传质模型。此外，我们使用流体体积法使用局部体积分数跟踪分散相的界面。虽然在低质量通量下的平行图案促进气泡运动表现出良好的传热性能，但由于其较高的成核位点密度，点状图案在高质量通量下表现出更好的性能。此外，非常宽或窄的疏水区域不适合传热。狭窄的区域限制了气泡的成核。交叉图案的疏水面积分数为 0.165，平行和点图案的疏水面积分数为 0.32，产生最佳的传热性能。