Experimental investigation of droplet formation in microchannel device with an embedded microsieve

doi:10.11949/0438-1157.20240593

Abstract

Abstract:

A sieve microchannel with embedded structure was designed and the droplet generation process of water-silicone oil system was studied. The dripping and jetting flow were observed under different flow rates of continuous phase and dispersed phase. The effects of two-phase flow rates and interfacial tension on the active pore number distribution and droplet size were investigated. The results showed that the number of active pores increased with the increase of two-phase capillary number. The droplet size decreased with the increase of continuous phase flow rate and decrease of interfacial tension. The droplet size increased in waves with the increase in dispersed phase flow rate. Based on the obtained results, an empirical correlation was proposed to predict the droplet size with good prediction performance. In addition, the effect of the microporous membrane as a flow resistance on the active pore number distribution and droplet size in two-pore microsieve was investigated. The activation of pore became easily under low flow rate of dispersed phase at the presence of microporous membrane as a flow resistance, which led to a smaller droplet size.

Key words: microchannels, two-phase flow, microsieve, droplet formation, flow regimes

摘要：

设计了一种具有嵌入式结构的筛孔微通道并研究了水-硅油体系的液滴生成过程。在不同的两相流量下观测到滴出流与喷射流两种流型，并考察了两相流量、界面张力对活化孔数量分布和液滴尺寸的影响。结果表明，随着分散相或连续相的毛细数Ca增加，筛孔活化数量增加；对于液滴尺寸，随着连续相流量的增加和界面张力的降低，液滴尺寸降低，而随着分散相流量的增加，液滴尺寸呈现波浪式增加。基于实验结果，建立了液滴尺寸预测模型，预测值与实验值吻合较好。此外，还考察了添加微孔膜阻件对活化孔数量分布和液滴尺寸的影响，发现微孔膜阻件能使分散相在更低流量下活化筛孔，生成尺寸更小的液滴。

关键词: 微通道, 两相流, 微筛孔, 液滴生成, 流域

CLC Number:

TQ 028.8

Wenna TANG, Hongchen LIU, Xiaotian MI, Liewei QIU, Mei YANG, Guangwen CHEN. Experimental investigation of droplet formation in microchannel device with an embedded microsieve[J]. CIESC Journal, 2024, 75(11): 4188-4195.

唐文娜, 刘宏臣, 米晓天, 秋列维, 杨梅, 陈光文. 嵌入式筛孔微通道内液滴生成规律研究[J]. 化工学报, 2024, 75(11): 4188-4195.

Figures/Tables 10

Table 1 Physical properties of the two-phase system

流体	密度 ρ/(kg/m³)	黏度 μ/(mPa·s)	界面张力 γ/(mN/m)
硅油	955	540	—
去离子水	998	0.98	41.47
0.1%（质量分数）SDS	998	0.98	11.83
1%（质量分数）SDS	985	0.98	8.89

Fig.1 (a) Schematic representation of the microsieve device; (b) Pore structure; (c) Sketch of the experimental setup

Fig.2 Typical liquid-liquid two-phase flow patterns of droplet formation in the three-pore microsieve device

Fig.3 Diagram of the active pore number distribution characterized by Cac and CadNumber of active pore: ×(water),-(0.1%SDS),＋(1%SDS) —1; hollow dot—2; solid dot—3

Fig.4 Effect of flow rates of continuous phase (a) and dispersed phase (b) on the droplet size for the silicone oil/water system

Fig.5 Effect of the ratio of continuous and dispersed phase flow rates on the droplet size for the silicone oil/water system in three-pore microsieve device

Fig.6 Effect of interfacial tension on the droplet size as a function of Qd in three-pore microsieve device (Qc=1.0 ml/min)

Fig.7 Comparison of the experimental ddrop/de with the calculated value

Fig.8 Effect of the microporous membrane as a flow resistance on the active pore distribution in two-pore microsieve

Fig.9 Effect of the microporous membrane as a flow resistance on the droplet size in two-pore microsieve(Qc=1 ml/min)

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