微通道内浆料体系中的气泡生成特性及尺寸预测

doi:10.11949/0438-1157.20190745

摘要/Abstract

摘要：

利用高速摄像仪对T型微通道内浆料体系中的气泡生成频率和气泡尺寸进行了研究。以氮气作为分散相，含0.35%（质量分数）表面活性剂（SDS）不同浓度玻璃珠的甘油-水溶液为连续相。实验考察了弹状流下气液两相流量、颗粒浓度以及浆料表观黏度对气泡生成频率及气泡尺寸的影响。结果表明：在弹状流下，当分散相流量一定时，随着连续相流量的增大，气泡的生成频率增大而气泡尺寸减小。当连续相流量一定时，随着分散相流量的增大，气泡生成频率和气泡尺寸均增大。随着颗粒浓度的增大，浆料的表面张力减小，表观黏度增大，气泡生成频率增大而气泡尺寸减小。提出了T型微通道内浆料体系中生成气泡尺寸的预测模型，模型具有良好的预测精度。

关键词: 微通道, 气泡, 频率, 尺寸, 浆料

Abstract:

The bubble generation process in liquid-solid slurry system in T-junction microchannel was visually investigated by a high-speed camera. The glycerol-water solutions containing 0.35%（mass） of surfactant (SDS) and different concentrations of glass beads were used as the continuous phase, nitrogen as the dispersed phase. The effects of gas and liquid flow rates, particle concentration and superficial viscosity of slurry on the bubble generation frequency and bubble size under the Taylor flow were studied. The results show that under the Taylor flow regime, when the flow rate of the dispersed phase is constant, the frequency of bubble generation increases but its length decreases with the increase of the flow rate of the continuous phase. As the flow rate of the continuous phase is fixed, both the formation frequency and size of bubble increase with the increase of the flow rate of the dispersed phase. When particle concentration increases, the surface tension decreases of the slurry but its superficial viscosity increases, the bubble generation frequency rises while its size declines. A prediction model for bubble size in the T-type microchannel slurry system is proposed, and the model has good prediction accuracy.

Key words: microchannel, bubble, frequency, size, slurry

中图分类号:

TQ 021.1

刘静, 朱春英, 周灏, 付涛涛, 马友光. 微通道内浆料体系中的气泡生成特性及尺寸预测[J]. 化工学报, 2020, 71(2): 544-551.

Jing LIU, Chunying ZHU, Hao ZHOU, Taotao FU, Youguang MA. Bubble formation of slurry system and size prediction in microchannel[J]. CIESC Journal, 2020, 71(2): 544-551.

图/表 10

图1 实验装置

Fig.1 Schematic diagram of experimental setup

图2 微通道结构

Fig.2 Schematic diagram of microfluidic device

表1 两相流体的物性数据

Table1 Physical properties of liquid and slurry used in experiment

Slurry (50% gly-water/0.35% SDS) C_s/%	Density, ρ/(kg/m³)	Superficial viscosity, μ/(mPa·s)	Surface tension, σ/(mN/m)
0	1123.2	4.41	39.66
0.4	1123.3	5.39	33.77
2	1123.5	5.78	31.27
3	1123.8	5.86	31.25
5	1123.9	6.06	30.29

图3 剪切速率和浆料表观黏度的关系

Fig.3 Relation between shear rate and apparent viscosity of slurry

图4 颗粒浓度对浆料表面张力及表观黏度的影响

Fig.4 Influence of particle concentration on surface tension and apparent viscosity of slurry

图5 不同操作条件下气-液-固三相流动状态

Fig.5 Flow regimes of gas-liquid-solid three-phase in microchannel under different operating conditions

图6 气液两相流量对气泡生成频率的影响（Cs = 0.4%）

Fig.6 Influences of gas and liquid-solid slurry flow rates on bubble formation frequency in microchannel

图7 颗粒浓度对气泡生成频率差值的影响

Fig.7 Effect of particle concentration on difference of bubble generation frequency

图8 气液流量比和固体颗粒浓度对生成气泡无量纲长度的影响

Fig.8 Effects of gas-liquid flow ratio and solid particle concentration on dimensionless length of bubble generation

图9 气泡长度的模型预测值与实验值的对比

Fig.9 Comparison of bubble length between predicting values and experimental data

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