Abstract In this paper, the pool boiling heat transfer performance of cylindrical microstructured surfaces that were fabricated using the dry etching technique was studied. The working fluid was FC-72, and the experimental conditions included four different liquid subcooling temperatures (0, 15, 25, and 35 K). The heated microstructured surfaces consist of smooth parts and circular micropillar blocks, which are classified as single-block type (MP-1), four-block type (MP-2), 16-block type (MP-3, MP-4, MP-5) or composite-block type (MP-6). The material that was used as the substrate was P doped silicon chip. The experimental results showed that the heat transfer coefficient (HTC) and the critical heat flux (CHF) of all of the microstructured surfaces are greatly enhanced compared with the smooth surface because the block divisions and blank area could effectively prevent vapor columns from coalescing. Among the microstructured surface types, surface MP-3 has the largest CHF with different subcooling, while its actual heat transfer area of microstructured surface is relatively small. Furthermore, the mechanism and behavior of vapor column coalescence under critical heat flux conditions were analyzed. The prediction of CHF by using the critical vapor column radius (rgc) was compared and analyzed with the experimental data. Finally, the critical metastability phenomenon was demonstrated, and its occurrence mechanism was explored and explained. The experimental results show that restricting the coalescence of the vapor column is an effective method to augment CHF, and a high CHF can be obtained even when the surface area enhancement ratio is relatively low.

中文翻译：

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分块微结构表面的池沸腾传热和临界蒸气柱聚结机制

摘要 本文研究了干蚀刻技术制备的圆柱形微结构表面的池沸腾传热性能。工作流体为 FC-72，实验条件包括四种不同的液体过冷温度（0、15、25 和 35 K）。加热的微结构表面由光滑部分和圆形微柱块组成，分为单块型（MP-1）、四块型（MP-2）、16块型（MP-3、MP-4、 MP-5) 或复合块型 (MP-6)。用作衬底的材料是P掺杂的硅芯片。实验结果表明，与光滑表面相比，所有微结构表面的传热系数（HTC）和临界热通量（CHF）都大大提高，因为块状分隔和空白区域可以有效地防止蒸汽柱聚结。在微结构表面类型中，MP-3表面具有不同过冷度的最大CHF，而其微结构表面的实际传热面积相对较小。此外，分析了临界热通量条件下蒸气柱聚结的机理和行为。将使用临界蒸气柱半径 (rgc) 预测的 CHF 与实验数据进行了比较和分析。最后，论证了临界亚稳态现象，并对其发生机制进行了探索和解释。