Preparation of aqueous two-phase droplets in improved T-shaped microchannel

doi:10.11949/0438-1157.20240723

Abstract

Abstract:

The preparation of aqueous two-phase droplets in the improved necking T-shaped microchannel and step T-shaped microchannel embedded capillary was studied, and the two microchannels were compared based on the droplet size. The jet-slug flow and jet-drop flow were observed, and the transition between flow patterns is controlled by the two-phase flow rates. In the step T-shaped microchannel embedded capillary, the generation range and stability of the droplets are obviously better than that of the necking T-shaped microchannel. The variations of droplet formation size in the two microchannels are similar, which decreases with the increase of continuous phase flow rate and increases with the increase of dispersed phase flow rate. However, the droplet size generated in the step T-shaped microchannel embedded capillary is smaller than that in the necking T-shaed microchannel. The prediction models of droplet size are established, which have good prediction performance in both microchannels.

Key words: aqueous two-phase system, droplet, microchannel, two-phase flow, microscale

摘要：

研究了改进的缩口T型微通道和毛细管嵌入阶梯式T型微通道内双水相液滴的制备，基于液滴尺寸对这两种微通道进行了比较。结果表明，其流型为喷射-弹状流和喷射-滴落流，流型的转变受到两相流率控制。而在毛细管嵌入阶梯式T型微通道内，液滴的生成范围和稳定程度明显优于缩口T型微通道。在两个微通道内液滴生成尺寸的变化规律是相似的，均随着连续相流率的增大而减小，随着分散相流率的增大而增大，但毛细管嵌入阶梯式T型微通道内生成的液滴尺寸相较于缩口T型微通道更小。建立了液滴尺寸的预测模型，对两种微通道均具有良好的预测效果。

关键词: 双水相系统, 液滴, 微通道, 两相流, 微尺度

CLC Number:

TQ 021.1

Panpan WEI, Yinan LIU, Chunying ZHU, Taotao FU, Xiqun GAO, Youguang MA. Preparation of aqueous two-phase droplets in improved T-shaped microchannel[J]. CIESC Journal, 2025, 76(2): 576-583.

魏攀攀, 刘怿楠, 朱春英, 付涛涛, 高习群, 马友光. 改进的T型微通道内双水相液滴的制备[J]. 化工学报, 2025, 76(2): 576-583.

Figures/Tables 10

Fig.1 Schematic diagram of necking T-shaped microchannel

Fig.2 Schematic diagram of step T-shaped microchannel embedded capillary

Fig.3 Schematic diagram of experimental setup

Table 1 Physical properties of the fluids used

初始浓度	相别	流体	密度ρ/(g/cm³)	黏度μ/(mPa·s)	表面张力σ/(mN/m)
24%（质量分数） PEG	连续相	PEG富相溶液	1.066	40.968	0.48
24%（质量分数）TSC	分散相	TSC富相溶液	1.143	2.421	0.48

Fig.4 Flow patterns of aqueous two-phase droplets in necking T-shaped microchannel

Fig.5 Typical unstable flow patterns in necking T-shaped microchannel

Fig.6 Flow regimes map of aqueous two-phase droplet

Fig.7 Influence of Ohnesorge number on flow patterns

Fig.8 Effect of flow rates on droplet size

Fig.9 Comparison of aqueous two-phase droplet size between experimental values and the predicted values

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