科研之友
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摘要
We propose a model to compute operating boundaries for on-chip continuous-phase separation of slug flow using capillary separators, verified by an extensive experimental study. The operating region of the device is described by two limits, defining the range of pressure drop across the separator at which full withdrawal of the continuous phase through the capillaries takes place while simultaneously the dispersed phase is prevented from entering. The lower bounding pressure is determined with a new non-empirical model by quantifying the effective number of capillaries in contact with the slug of continuous phase. The upper limit is given by the capillary pressure, calculated with the Young-Laplace equation. Experimental validation is performed by separating water-toluene slug flow in glass-silicon microdevices of five different geometries, with various capillary widths and lengths. Operating windows are well predicted with the new model, and an alternative semi-empirical approach is proposed by fitting the Hagen-Poiseuille equation to the measured pressure boundaries. Finally, a scaling law to predict lengths of slugs and droplets generated in a T-junction allows to model the pressure limits without the need of any experimental data.
- 出版日期2017-9
