Laboratory of Chemical Reactor Engineering, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
Lab Chip. 2014 May 7;14(9):1632-49. doi: 10.1039/c3lc51307f. Epub 2014 Mar 20.
We report a three-phase slug flow and a parallel-slug flow as two major flow patterns found under the nitrogen-decane-water flow through a glass microfluidic chip which features a long microchannel with a hydraulic diameter of 98 μm connected to a cross-flow mixer. The three-phase slug flow pattern is characterized by a flow of decane droplets containing single elongated nitrogen bubbles, which are separated by water slugs. This flow pattern was observed at a superficial velocity of decane (in the range of about 0.6 to 10 mm s(-1)) typically lower than that of water for a given superficial gas velocity in the range of 30 to 91 mm s(-1). The parallel-slug flow pattern is characterized by a continuous water flow in one part of the channel cross section and a parallel flow of decane with dispersed nitrogen bubbles in the adjacent part of the channel cross section, which was observed at a superficial velocity of decane (in the range of about 2.5 to 40 mm s(-1)) typically higher than that of water for each given superficial gas velocity. The three-phase slug flow can be seen as a superimposition of both decane-water and nitrogen-decane slug flows observed in the chip when the flow of the third phase (viz. nitrogen or water, respectively) was set at zero. The parallel-slug flow can be seen as a superimposition of the decane-water parallel flow and the nitrogen-decane slug flow observed in the chip under the corresponding two-phase flow conditions. In case of small capillary numbers (Ca ≪ 0.1) and Weber numbers (We ≪ 1), the developed two-phase pressure drop model under a slug flow has been extended to obtain a three-phase slug flow model in which the 'nitrogen-in-decane' droplet is assumed as a pseudo-homogeneous droplet with an effective viscosity. The parallel flow and slug flow pressure drop models have been combined to obtain a parallel-slug flow model. The obtained models describe the experimental pressure drop with standard deviations of 8% and 12% for the three-phase slug flow and parallel-slug flow, respectively. An example is given to illustrate the model uses in designing bifurcated microchannels that split the three-phase slug flow for high-throughput processing.
我们报告了两种主要的流动模式，即三相弹状流和并联弹状流，这两种模式是在氮气-癸烷-水通过一个具有 98μm 水力直径的长微通道的玻璃微流控芯片中发现的，该微通道连接到一个横流混合器。三相弹状流模式的特点是癸烷液滴中含有单个拉长的氮气气泡的流动，这些气泡被水弹状流隔开。这种流动模式是在癸烷的表观速度（约 0.6 至 10mm/s）低于给定的表观气速（30 至 91mm/s）下观察到的。并联弹状流模式的特点是在通道横截面的一部分中连续流动水，而在通道横截面的相邻部分中癸烷平行流动并分散有氮气气泡，这种模式是在癸烷的表观速度（约 2.5 至 40mm/s）高于给定的每个表观气速下水的表观速度下观察到的。三相弹状流可以被视为在第三相（即氮气或水）流量为零时在芯片中观察到的癸烷-水和氮气-癸烷弹状流的叠加。并联弹状流可以被视为在相应的两相流条件下在芯片中观察到的癸烷-水并联流和氮气-癸烷弹状流的叠加。在小的毛细数（Ca≪0.1）和韦伯数（We≪1）的情况下，在弹状流下扩展了开发的两相压降模型，以获得三相弹状流模型，其中“氮气在癸烷中”液滴被假定为具有有效粘度的拟均匀液滴。将并联流和弹状流压降模型结合起来得到了并联弹状流模型。所得到的模型描述了实验压降，三相弹状流和并联弹状流的标准偏差分别为 8%和 12%。给出了一个示例来说明该模型在设计用于高流量处理的分叉微通道以分裂三相弹状流中的应用。
