Fundamentals of particle charging by free electrons in electrical coronas

电晕中自由电子对粒子充电的基本原理

• 批准号: 464808350
• 负责人: Professor Dr.-Ing. Ulrich Riebel
• 金额: --
• 依托单位: Lehrstuhl Mechanische Verfahrenstechnik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/464808350?language=en
• 关键词: Fundamentals; particle; charging; free; electrons

The electrical charging of aerosols is an important process in many technical applications and in aerosol measurements. The kinetics of aerosol charging by positive and negative gas ions based on the mechanisms of diffusion charging and field charging is well known. But in some situations aerosols are being charged much faster and to a much higher level than expected. As a rule, this effect can be attributed to aerosol charging by free electrons. This so called “Electronic Charging” of aerosols is to be found especially with low concentrations of electronegative gases or with elevated temperatures. In these cases the formation of negative gas ions is delayed or does not take place. Hence, the current transport in a corona discharge will occur in part or almost completely by free electrons. In electrostatic fields, the free electrons will reach very high (non-equilibrium) electron temperatures, and aerosol particles can reach very high charging levels by electronic diffusion charging. So far, there is a lack of systematic investigations on electronic charging of aerosols. In addition, there is a lack of basic data which would be needed for a theoretical prediction of electronic charging in technically relevant gas mixtures. Within the project, the fundamentals for modelling quantitatively the electronic charging of aerosols in corona discharges shall be provided and validated. This will be done first with the system N2-O2-H2O as a technically relevant gas mixture model and with submicron aerosols. For measurements of the charge carrier kinetics, classical drift tube experiments will be adapted to the conditions. As well, measurements of aerosol charging kinetics will be done first in a drift tube within a homogeneous electrostatic field. Further validations will be done with corona discharges in a wire-tube-geometry.

气溶胶的电荷是许多技术应用和气溶胶测量中的重要过程。众所周知，基于扩散充电和现场充电的机理，正气离子和负气离子的气溶胶动力学动力学是众所周知的。但是在某些情况下，气溶胶的费用要比预期的要快得多。通常，这种效果可以归因于自由电子的气溶胶充电。可以发现这种所谓的气溶胶“电子充电”，尤其是在低浓度的电源飞行或温度升高的情况下。在这些情况下，负气离子的形成被延迟或不发生。因此，电晕放电中的当前运输将部分或几乎完全由自由电子发生。在静电场中，游离电子将达到非常高的（非平衡）电子温度，并且通过电子扩散充电，气溶胶颗粒可以达到非常高的充电水平。到目前为止，缺乏对气溶胶电子充电的系统投资。此外，缺乏基本数据，对于技术相关的气体混合物中电子充电的理论预测将需要。在项目中，应定量建模的基本面对电晕放电中气溶胶的电子充电进行验证和验证。这将首先使用系统N2-O2-H2O作为技术相关的气体混合模型和亚微米气溶胶进行。为了测量电荷载体动力学，经典的漂移管实验将适应条件。同样，气溶胶充电动力学的测量将首先在均匀静电场的漂移管中进行。将在电线管数字中排放的电晕放电将进一步验证。