Effect of Functional Surfaces with Gradient Mixed Wettability on Flow Boiling in a High Aspect Ratio Microchannel
Effect of Functional Surfaces with Gradient Mixed Wettability on Flow Boiling in a High Aspect Ratio Microchannel
复制标题
DOI：
10.3390/fluids5040239
复制
发表时间：
2020-12-01
期刊：
影响因子：
1.9
通讯作者：
Kosar, Ali
中科院分区：
文献类型：
--
作者：
Ahmadi, Vahid Ebrahimpour;Aboubakri, Akam;Kosar, Ali
流动沸腾是最有效的相变传热机制之一，并且强烈依赖于表面性质。表面润湿性是影响流动沸腾传热性能的重要参数。接触角决定了成核位点的数量以及气泡动力学和流动模式。本文介绍了三种新一代的混合润湿表面，并将它们与一种完全疏水的表面参考样品进行了比较。混合润湿性基底具有五个区域，即完全Al 2 O3（疏水区）区域、具有不同A* 值的三种不同图案化配置和完全SiO2（亲水区）区域，其中A* 定义为A（Al 2 O3）/A（总）（疏水比）。在不同的壁面热通量和三种不同的质量通量下，得到了每个表面的沸腾传热结果。根据所获得的结果，显着增强传热（高达56.7%），可以得到与双亲性表面相比，参考样品（疏水表面）。进行流动可视化证明，测试的双亲表面通过减少泡状流区和延长段塞区来增强传热。
Flow boiling is one of the most effective phase-change heat transfer mechanisms and is strongly dependent on surface properties. The surface wettability is a crucial parameter, which has a considerable effect on the heat transfer performance, particularly in flow boiling. The contact angle determines the number of nucleation sites as well as bubble dynamics and flow patterns. This study introduces three new generation mixed wettability surfaces and compares them with a wholly hydrophobic surface reference sample, in flow boiling in a high aspect ratio microchannel. The mixed wettability substrates have five regions as fully Al2O3, (hydrophobic zone) region, three different patterned configurations with various A* values, and fully SiO2 (hydrophilic zone) region, where A* is defined as A (Al2O3)/A (total) (hydrophobicity ratio). Boiling heat transfer results were obtained for each surface at various wall heat fluxes and three different mass fluxes. According to the obtained results, significant enhancements in heat transfer (by up to 56.7%) could be obtained with biphilic surfaces compared to the reference sample (hydrophobic surface). Performed flow visualization proves that the tested biphilic surfaces enhance heat transfer by reducing the bubbly flow regime and extending the slug regime.