Sub-micrometer dropwise condensation under superheated and rarefied vapor condition.
Sub-micrometer dropwise condensation under superheated and rarefied vapor condition.
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DOI：
10.1021/la102642r
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发表时间：
2010-11-16
期刊：
影响因子：
--
通讯作者：
Son SY
中科院分区：
文献类型：
--
作者：
Anand S;Son SY
在过冷表面下，饱和或过热蒸汽的相变是自然界中最常见的现象之一。这种转变之后的相变模式取决于表面性质，如接触角和系统的热力学条件。在目前的研究中，采用实验方法来研究液滴在部分湿润表面上生长的物理原理。在静态接触角为60°、无不可冷凝气体的情况下，在低压4 ~ 5 torr下，过热蒸汽在过冷硅表面冷凝，并利用亚微观空间分辨率的环境扫描电子显微镜（ESEM）对冷凝过程进行了监测。在聚结事件结束单个液滴生长之前，以孤立液滴尺寸增长的形式分析了冷凝过程。作为时间函数的液滴生长表明，随着液滴尺寸的增大，生长速率降低。这种行为表明，在更大的时间尺度上存在着一个整体的液滴生长规律，目前在其短暂的时间间隔内的观测结果可以适用于这个规律。基于动力学理论的理论模型进一步支持了实验观测结果，表明在冷凝液滴表面直接通过界面质量传递发生生长的机制。在部分润湿的情况下，还发现了亚微观液滴成核和生长的证据。
Phase change accompanying conversion of a saturated or superheated vapor in presence of subcooled surfaces is one of the most common occurring phenomena in nature. The mode of phase change which follows such a transformation is dependent upon surface properties like as of contact angle and thermodynamic conditions of the system. In present studies, an experimental approach is used to study the physics behind droplet growth on a partially wetting surface. Superheated vapor at low pressures of 4–5 torr was condensed on subcooled silicon surface with static contact angle as of 60° in absence of non-condensable gases, and the condensation process monitored using Environmental Scanning Electron Microscope (ESEM) with submicroscopic spatial resolution. The condensation process was analyzed in the form of size growth of isolated droplets for before a coalescence event ended the regime of single droplet growth. Droplet growth obtained as a function of time reveals that the rate of growth decreases as the droplet increases in size. This behavior is indicative of an overall droplet growth law existing over larger time scales of which the current observations in their brief time intervals could be fitted in. A theoretical model based on kinetic theory further support the experimental observations indicating a mechanism where growth occurs by interfacial mass transport directly on condensing droplet surface. Evidence was also found which establishes the presence of submicroscopic droplets nucleating and growing in between microscopic droplets for partially wetting case.
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DOI：
10.1016/0166-6622(91)80126-9
发表时间：
1991-05-01
期刊：
COLLOIDS AND SURFACES
影响因子：
--
作者：
BRISCOE, BJ;GALVIN, KP
通讯作者：
GALVIN, KP
DOI：
10.1016/0017-9310(67)90114-7
发表时间：
1967-01-01
影响因子：
5.2
作者：
GRIFFITH, P;LEE, MS
通讯作者：
LEE, MS
影响因子：
--
作者：
HOLDEN, KM;WANNIARACHCHI, AS;ROSE, JW
通讯作者：
ROSE, JW
DOI：
10.1111/j.1365-2818.1994.tb03445.x
发表时间：
1994-03-01
期刊：
JOURNAL OF MICROSCOPY-OXFORD
影响因子：
--
作者：
CAMERON, RE;DONALD, AM
通讯作者：
DONALD, AM
影响因子：
41.2
作者：
Donald, AM
通讯作者：
Donald, AM