针-环电极配置下电场对气泡分散特性的影响

doi:10.16085/j.issn.1000-6613.2021-1463

化工进展 ›› 2022, Vol. 41 ›› Issue (6): 2931-2938.DOI: 10.16085/j.issn.1000-6613.2021-1463

针-环电极配置下电场对气泡分散特性的影响

张伟(), 王军锋(), 苏巧玲, 吴天一

江苏大学能源与动力工程学院，江苏镇江 212013

收稿日期:2021-07-12 修回日期:2021-10-08 出版日期:2022-06-10 发布日期:2022-06-21
通讯作者: 王军锋
作者简介:张伟（1992—），男，博士研究生，研究方向为荷电多相流理论及工程应用。E-mail：zhangwei0112@ujs.edu.cn。
基金资助:
国家自然科学基金(51761145011);江苏省研究生科技与实践创新计划(KYCX19_1599)

Effect of electric field on bubble dispersion characteristics with needle-ring electrode configuration

ZHANG Wei(), WANG Junfeng(), SU Qiaoling, WU Tianyi

School of Energy and Power Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu, China

Received:2021-07-12 Revised:2021-10-08 Online:2022-06-10 Published:2022-06-21
Contact: WANG Junfeng

摘要/Abstract

摘要：

在多相反应系统中，外加电场因具有促进离散相在连续相中的分散并强化相间传质的优势而受到广泛关注。基于此，本研究设计并构建了静电液气分散实验测量系统，通过在针-环电极间施加高压直流电产生非均匀电场，以乙醇为连续相、空气为离散相，在考虑气体流量和施加电压影响因素的基础上，采用高速摄像技术对电场作用下的气泡分散过程进行了可视化测量。结果表明，气泡在乙醇中的分散主要呈现滴状、混合和喷雾3种模式。以量纲为1气泡直径（ζ）表征的气泡尺寸随着电邦德数（Bo_E）的增大显著减小，随着气体韦伯数（We_g）的增加而增大，其中在混合模式和喷雾模式下的微气泡尺寸基本在20μm以下。增大Bo_E和We_g均能促进气泡的产生，但Bo_E的影响效果更加明显。同时，发现气泡分散模式的转变主要取决于Bo_E，增大We_g使气泡分散模式的转变趋势延缓。此外，基于本研究实验数据建立了ζ与Bo_E和We_g相关的气泡尺寸预测模型，针对ζ ≤ 5的气泡，该模型结果与实验结果高度吻合。通过低能量消耗实现小气泡的生产一直以来是技术难题，采用电场强化气泡分散为发展相应技术实现强化多相系统中相间混合和传质提供了新思路。

关键词: 静电液气分散, 针-环电极, 气泡模式, 气泡尺寸

Abstract:

In multiphase reaction systems, applied electric field have been widely noted for the advantages in promoting the dispersion of discrete phases in continuous phases and enhancing mass transfer. In this study, an electrostatic liquid-gas dispersion experimental measurement system was designed and constructed to create a non-uniform electric field by applying a high-voltage direct current between needle-ring electrodes, with ethanol as the continuous phase and air as the discrete phase. The bubble dispersion process under the electric field was visualized and measured by high-speed photography, taking into account the impact factors of gas flow and applied voltage. The results showed that the bubble dispersion was associated with three typical patterns in the manipulated parameter regions, including the dripping, mixed, and spraying modes. The bubble size, characterized by the dimensionless bubble diameter (ζ), decreased significantly with increasing electric Bond number (Bo_E) and increased with rising gas Weber number (We_g), where the microbubble size was basically below 20μm in the mixed and spraying modes. Increasing Bo_E and We_g both promoted the production of bubbles, but the effect of Bo_E was more obvious. Meanwhile, it was found that the transition of bubble dispersion patterns depended strongly on the Bo_E, and the rise in We_g tended to slow down the transition process. In addition, a predication model of ζ as a function of Bo_E and We_g was established for the dripping mode of bubbles based on the present experiment data, and the results of this model were in high agreement with the experimental results at ζ ≤ 5. The production of small bubbles through low energy consumption had been a technical challenge, and the use of electric field to enhance bubble dispersion provided new ideas for the development of corresponding technologies to achieve enhanced interphase mixing and mass transfer in multiphase systems.

Key words: electrostatic liquid-gas dispersion, needle-ring electrodes, bubble patterns, bubble size

中图分类号:

TK175

张伟, 王军锋, 苏巧玲, 吴天一. 针-环电极配置下电场对气泡分散特性的影响[J]. 化工进展, 2022, 41(6): 2931-2938.

ZHANG Wei, WANG Junfeng, SU Qiaoling, WU Tianyi. Effect of electric field on bubble dispersion characteristics with needle-ring electrode configuration[J]. Chemical Industry and Engineering Progress, 2022, 41(6): 2931-2938.

图/表 11

图1 静电液-气分散实验测量系统

表1 相关材料物性参数

项目	空气	无水乙醇
密度ρ/kg·m^-3	1.205	791
相对介电常数	1	24.3
表面张力σ/N·m^-1	—	22.14×10^-3
动力黏度μ/Pa·s	18.4×10^-6	1.17
电导率K/S·m^-1	?10^-15	5.1×10^-5

图2 电场作用下的液-气界面及受力分析

图3 滴状模式气泡的瞬态演化过程

图4 混合模式气泡的瞬态演化行为

图5 喷雾模式气泡瞬态图像

图6 量纲为1气泡直径随电邦德数的变化

图7 不同气体韦伯数下气泡尺寸随电邦德数的变化

图8 气泡尺寸预测模型验证

图9 不同韦伯数和电邦德数条件下的气泡产生数量统计结果

图10 气泡分散模式相图

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针-环电极配置下电场对气泡分散特性的影响

Effect of electric field on bubble dispersion characteristics with needle-ring electrode configuration

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