电场作用下基面液滴蒸发与内部流动数值模拟

doi:10.16085/j.issn.1000-6613.2021-0677

摘要/Abstract

摘要：

为探究电场强化基面液滴蒸发的原理，本文采用有限元方法，对外加电场作用下的固体基面上液滴的蒸发过程进行了数值模拟，对比了不同电导率液滴的蒸发过程，分析了电场、液滴蒸发速率和内部流动的影响及其成因，以及液滴在电场作用下的内部流动与液滴传热传质的关系，结果表明，电场力的作用能够显著强化液滴内部的流动，对液滴的传热传质具有促进作用。此外，本文分析了温度对电场下基面液滴蒸发及内部流动的影响，发现温度对电场、液滴内部流动及蒸发的强化作用也有着较为明显的影响：对于电导率较低的纯水液滴，当电场强度低于和高于临界值6kV/cm时，温度对电场强化液滴内部流动和蒸发的影响有所不同；对于电导率较高的盐酸液滴，温度对电场强化液滴内部流动和蒸发的影响随电场强度升高均较大。本文为发展高效静电喷雾冷却技术提供了研究基础。

关键词: 液滴, 蒸发, 电场, 电流体动力学, 数值模拟

Abstract:

In order to study the principle of enhancing substrate droplet evaporation by electric field, the evaporation process of droplets on solid substrate under external electric field was numerically simulated by finite element method. The effect of electric field on the evaporation rate and internal flow of droplet and its reasons were analyzed by comparing cases of droplets with different electric conductivities. The relationship between the internal flow and heat and mass transfer of droplet was also analyzed. The results showed that the effect of electric field can significantly enhance the internal flow and promote the heat and mass transfer of droplets. In addition, the effect of electric field on droplet evaporation and internal flow was analyzed. It was found that the effect of temperature on the internal flow and evaporation of droplets is also obvious. For the pure water droplet with low conductivity, when the electric field intensity was lower than and higher than the critical value 6kV/cm, the effect of temperature on the internal flow and evaporation of electric field enhanced droplets was different, and for the HCl droplet with high conductivity, temperature has great influence on electric field enhanced droplet influx and evaporation. The current study provides a research foundation for the development of efficient electrostatic spray cooling technology.

Key words: droplet, evaporation, electric field, electrohydrodynamics, numerical simulation

中图分类号:

TK018

张天昊, 许浩洁, 吴天一, 李步发, 王军锋. 电场作用下基面液滴蒸发与内部流动数值模拟[J]. 化工进展, 2022, 41(2): 609-618.

ZHANG Tianhao, XU Haojie, WU Tianyi, LI Bufa, WANG Junfeng. Numerical simulation of evaporation and internal flow of substrate droplet under electric field[J]. Chemical Industry and Engineering Progress, 2022, 41(2): 609-618.

图/表 14

图1 物理模型示意图

图2 模型验证

图3 基面水滴蒸发速率随电场强度的变化

图4 水滴蒸发过程中的内部流型及速率分布

图5 水滴最大内部流动速率随电场强度的变化

图6 E=10kV/cm时盐酸液滴内部的流场

图7 不同电导率液滴所受电场力大小分布和液滴表面应力、表面张力方向

图8 基面温度为40℃时无电场和有电场的情况下水滴附近空气域的流场

图9 水滴表面热通量与电场强度的关系

图10 不同电场强度时液滴内部的温度场分布

图11 不同基面温度时水滴蒸发速率随电场强度的变化

图12 不同电场强度和基面温度的情况下基面上水滴内部的流场

（t=1s）

图13 不同基面温度时水滴内部最大流动速率随电场强度的变化

图14 盐酸液滴蒸发速率、内部最大流动速率随电场强度的变化

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