Abstract Electrostatic charging and deposition of a liquid nano-aerosol was studied in dry air and in technical (3.6 % O2) nitrogen. The experiments have shown that electronic charging of aerosols can be important in technical scale electrostatic precipitators (ESPs). Already at operation voltages just slightly above the corona onset voltage, the contribution of the free electrons to the overall current is estimated to be around 50 %. Due to the high temperature of free electrons, diffusion charging by free electrons allows to reach exceptionally high particle charge and extremely high precipitation efficiency. A strongly simplified theoretical model was developed, which gives a good prediction of particle charge based on averaged values of particle diameter, current density, electric field strength, electron temperature and residence time. The ion mobilities were determined by fitting the current-voltage characteristics with a modified Townsend (Monrolin et al. 2018) equation and are significantly higher than the values typically used to describe diffusion charging in air. This may be ascribed to the very dry gas phase and the short average lifespan of the ions under ESP conditions, which is in the order of 1 ms. From the practical point of view, electronic charging might be relevant in a number of technical applications, including high temperature ESPs, ESP applications in dry and oxygen-free gases and pulsed corona systems.

中文翻译：

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工业氮中纳米粒子的静电充电和沉淀：热自由电子的高效扩散充电

摘要 在干燥空气和工业 (3.6% O2) 氮气中研究了液体纳米气溶胶的静电充电和沉积。实验表明，气溶胶的电子充电在技术规模的静电除尘器 (ESP) 中很重要。在工作电压略高于电晕开始电压时，自由电子对总电流的贡献估计约为 50%。由于自由电子的高温，自由电子的扩散充电可以达到极高的粒子电荷和极高的沉淀效率。开发了一个高度简化的理论模型，该模型基于粒子直径、电流密度、电场强度、电子温度和停留时间的平均值对粒子电荷进行了良好的预测。离子迁移率是通过将电流-电压特性与修改后的 Townsend（Monrolin 等人，2018 年）方程拟合来确定的，并且明显高于通常用于描述空气中扩散充电的值。这可能归因于非常干燥的气相和 ESP 条件下离子的短平均寿命，约为 1 ms。从实用的角度来看，电子充电可能与许多技术应用相关，包括高温 ESP、干燥和无氧气体中的 ESP 应用以及脉冲电晕系统。这可能归因于非常干燥的气相和 ESP 条件下离子的短平均寿命，约为 1 ms。从实用的角度来看，电子充电可能与许多技术应用相关，包括高温 ESP、干燥和无氧气体中的 ESP 应用以及脉冲电晕系统。这可能归因于非常干燥的气相和 ESP 条件下离子的短平均寿命，约为 1 ms。从实用的角度来看，电子充电可能与许多技术应用相关，包括高温 ESP、干燥和无氧气体中的 ESP 应用以及脉冲电晕系统。