非均匀电场对高黏流体中气泡分散特性的影响

doi:10.16085/j.issn.1000-6613.2023-0582

摘要/Abstract

摘要：

电场强化多相流相间分散和传质技术广泛应用于化工生产领域，气泡的尺寸和分散行为以及连续相的物理性质是影响多相流系统中传质效率的重要因素。本研究设计并搭建了荷电液气分散实验平台，对非均匀电场作用下气泡在高黏流体中的分散行为进行可视化研究。捕捉了气泡在生长和分散过程中的形貌特征，研究分析了电场强度和气体流量对气泡分散行为和气泡尺寸的影响。实验结果表明，随着电场强度的增大，当电邦德数（Bo_E）达到4.5时，空气在甘油中的分散行为由滴状模式转变为串珠模式；而在达到8.7后又转变为混合模式，并最终在电邦德数达到17.8时转变为电晕模式。气泡直径随电场强度的增大显著减小，相比于无电场条件下的气泡尺寸，当电邦德数达到6.4时气泡直径减小了80%。在混合模式下气泡破碎成大量微气泡，微气泡直径在100μm以下，从而有效增加了气液两相接触面积。同时，研究表明气泡分散模式的转变主要取决于电场强度，增大气体流量对气泡分散模式的转变和气泡直径的影响较小。在现有的数据基础上，在0<Bo_E<16范围内建立了气泡直径与电邦德数相关的预测模型。该研究结果可为电场作用下复杂流体中气泡的生长和分散行为提供参考。

关键词: 非均匀电场, 气泡模式, 气泡尺寸, 黏性流体, 电流体动力学

Abstract:

Electric field enhanced multiphase flow technology for interphase dispersion and mass transfer is widely used in chemical production. The size and dispersion behavior of bubbles and the physical properties of the continuous phase are important factors affecting the mass transfer efficiency in multiphase flow systems. In this study, a charged liquid-gas dispersion experimental platform was designed and built to visually study the dispersion behavior of bubbles in a high-viscosity fluid under the action of a non-uniform electric field. The morphological characteristics of the bubbles during the growth and dispersion process were recorded, and the effects of electric field strength and gas flow rate on the bubble dispersion behavior and bubble size were analyzed. The experimental results indicated that with the increase of electric field intensity, the dispersion behavior of air in glycerol underwent transitions from dripping mode to bead mode when the electric Bond number (Bo_E) reached 4.5. After reaching 8.7, it further transformed into mixed mode and finally corona mode when the electric Bond number reached 17.8. The bubble diameter decreased significantly with increasing electric field strength. Compared to the bubble size under no electric field, the bubble diameter decreased by 80% when the electric Bond number reached 6.4. In the mixed mode, the bubbles broke into numerous microbubbles, with microbubble diameters below 100μm. This effectively increased the interface area between the gas and liquid phases. Meanwhile, the study showed that the transition of the bubble dispersion mode mainly depended on the electric field strength, and the increase of the gas flow rate had little effect on the transition of the bubble dispersion mode and the bubble diameter. Based on the existing data, bubble diameter prediction model related to the electric Bond number in the range 0<Bo_E<16 was established. The results of this study could provide reference for the growth and dispersion behavior of bubbles in complex fluids under the action of electric fields.

Key words: non-uniform electric field, bubble patterns, bubble size, viscous fluid, electro-hydro dynamics(EHD)

中图分类号:

TK175

何发超, 刘海龙, 李昌烽, 王军锋. 非均匀电场对高黏流体中气泡分散特性的影响[J]. 化工进展, 2024, 43(4): 1774-1782.

HE Fachao, LIU Hailong, LI Changfeng, WANG Junfeng. Effect of non-uniform electric field on bubble dispersion characteristics in high-viscosity fluid[J]. Chemical Industry and Engineering Progress, 2024, 43(4): 1774-1782.

图/表 13

图1 荷电液气分散可视化测量系统示意图

表1 实验中所用介质物性参数

介质种类	密度 /g∙mL^-1	相对介电常数	表面张力 /mN∙m^-1	动力黏度 /mPa∙s
空气	1.205×10^-3	1		18.1×10^-6
甘油	1.261	37	61.9	1499

图2 针-环电极配置下的电场作用及电势分布

图3 滴状模式下气泡的瞬态演化过程

图4 串珠模式下气泡的瞬态演化过程

图5 混合模式下气泡的瞬态演化过程

图6 电晕模式下气泡的瞬态演化过程（BoE=17.8）

图7 不同气体流量和电场强度条件下的气泡分散行为

图8 基于电邦德数和气体流量下的气泡分散模式相图

图9 不同电邦德数和气体流量下的气泡产生频率

图10 气泡直径随电邦德数的变化

图11 不同气体流量下气泡尺寸随电邦德数的变化

图12 气泡尺寸预测模型的验证

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