Experimental and theoretical approaches on droplet formation from a micrometer screen hole
Experimental and theoretical approaches on droplet formation from a micrometer screen hole
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DOI：
10.1016/j.memsci.2005.05.017
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发表时间：
2005-12
影响因子：
9.5
通讯作者：
Jianhong Xu;G. Luo;G. G. Chen-G.;Jianchen Wang
中科院分区：
文献类型：
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作者：
Jianhong Xu;G. Luo;G. G. Chen-G.;Jianchen Wang
应用横流条件下微米筛孔的液滴形成过程来研究微混合和膜乳化等高前景过程中的液滴行为。使用三种不同界面张力的工作系统，研究了流速和界面张力对液滴形成的影响。为了阐明系统性质和流量的影响，建立了基于力平衡的理论模型，其中定义了分离周期参数和代表拖曳力扭矩分数的无量纲数x，以区分是否应考虑分离周期的影响。结果发现，对于界面张力为51.0mN/m的体系，分散相流量对液滴直径影响较小。并且可以直接用扭矩平衡方程来预测液滴尺寸。而对于界面张力分别为1.7和8.13mN/m的体系，分散相流量的增加导致液滴尺寸增加。因此，应考虑脱离期的影响。利用理论模型，可以将分离时间td拟合为x的函数，并且计算的液滴直径与实验值非常吻合。
The droplet formation process from a micrometer screen hole under crossflow conditions was applied to study the droplet behavior in the high-promising processes of micromixing and membrane emulsification. Three working systems with different interfacial tension were used, and the effects of flow rates and interfacial tension on droplet formation were investigated. To elucidate the influence of systems’ properties and flow rates, a theoretical model based on force balance has been developed, in which a parameter of detachment period and a dimensionless number x meaning the drag force torque fraction have been defined to distinguish whether the influence of detachment period should be considered. It was found that the dispersed phase flow rate has little influence on the droplet diameter for the system with large interfacial tension of 51.0mN/m. And the droplet size can be predicted with the torque balance equation directly. While for the systems with interfacial tension of 1.7 and 8.13mN/m, respectively, the increase of the dispersed phase flow rate resulted in droplet size increment. Therefore, the effect of detachment period should be considered. Using the theoretical model, the detachment time tdcan be fitted as a function of x, and the calculated droplet diameters are in good agreement with the experimental values.