Generation of Oil Droplets in a Non-Newtonian Liquid Using a Microfluidic T-Junction
Generation of Oil Droplets in a Non-Newtonian Liquid Using a Microfluidic T-Junction
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DOI：
10.3390/mi6121458
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发表时间：
2015-12-01
期刊：
影响因子：
3.4
通讯作者：
Piccin, Evandro
中科院分区：
文献类型：
--
作者：
Chiarello, Enrico;Derzsi, Ladislav;Piccin, Evandro
我们比较了t型结微流控装置中牛顿流体和非牛顿流体中油滴的形成。作为牛顿流体，我们使用甘油水溶液，而作为非牛顿流体，我们使用黄原胶水溶液，黄原胶是一种坚硬的棒状多糖，具有很强的剪切减薄作用。在挤压状态下，发现甘油溶液中油滴的形成与分散流速与连续流速之比以及与连续相相关的毛细数成比例。改用黄原胶溶液似乎不会显著改变液滴形成过程。相对于牛顿液体的任何定量差异都可以通过适当选择毛细管数来解释，毛细管数对应于取决于流速的有效黄原胶粘度。在t型结的正常操作条件下，我们已经推导出粘度的大量变化，其数量级为10或更多。这可以估计黄原胶溶液的实际剪切速率，从几十到几百s（-1）不等。
We have compared the formation of oil drops in Newtonian and non-Newtonian fluids in a T-junction microfluidic device. As Newtonian fluids, we used aqueous solutions of glycerol, while as non-Newtonian fluids we prepared aqueous solutions of xanthan, a stiff rod-like polysaccharide, which exhibit strong shear-thinning effects. In the squeezing regime, the formation of oil droplets in glycerol solutions is found to scale with the ratio of the dispersed flow rate to the continuous one and with the capillary number associated to the continuous phase. Switching to xanthan solutions does not seem to significantly alter the droplet formation process. Any quantitative difference with respect to the Newtonian liquid can be accounted for by a suitable choice of the capillary number, corresponding to an effective xanthan viscosity that depends on the flow rates. We have deduced ample variations in the viscosity, on the order of 10 and more, during normal operation conditions of the T-junction. This allowed estimating the actual shear rates experienced by the xanthan solutions, which go from tens to hundreds of s(-1).