Experimental study of diffusion charging of aerosols
Experimental study of diffusion charging of aerosols
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气溶胶扩散荷电实验研究
DOI：
10.2172/7356886
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发表时间：
1976
期刊：
影响因子：
--
通讯作者：
D. Pui
中科院分区：
文献类型：
--
作者：
D. Pui
从理论和实验两个方面研究了单极气体离子对气溶胶粒子的带电作用。研究的主要目的是精确测定不同充电条件下的气溶胶粒子荷电，并将实验结果与理论预测的结果进行比较。实验使用了振动孔发生器产生的单分散油酸气溶胶、静电分级方法产生的单分散氯化钠和邻苯二甲酸二辛酯气溶胶以及烟雾室内气体SO/SUB2/光化学转化产生的硫酸气溶胶。实验的粒度范围为0.0075~5.04µm。相应的克努森数范围(Kn=λ/subi//a，lambda/subi/=离子的平均自由程，a=粒子半径)从0.0056到3.86.充电参数n/sub0/t在2.56×10/sup 6/至5.1×10/sup 7/ion-S/cc之间变化，其中n/sub0/是离子浓度，t是充电时间。将计算结果与现有的气溶胶荷电理论进行了比较，结果表明，在连续流区(Kn>；1)和过渡流区(Kn近似值)下，理论与实验符合得很好。或等于1)，当离子平均自由程与粒子大小相比不再小时，实验数据与现有的电荷理论之间存在相当大的差异。建立了一个半经验方程，在实验所涉及的整个粒度范围和充电参数范围内与实验数据符合得很好。给出了粒子上电荷分布随粒子大小和电荷参数n/sub0/t的函数关系的理论结果。(Auth)(更少)
The electrical charging of aerosol particles by unipolar gaseous ions was studied theoretically and experimentally. The primary objective of the study was to make precise determinations of the aerosol particle charge under various conditions of charging and to compare the experimental results with those predicted by theory. Experiments were performed using monodisperse oleic acid aerosols generated by a vibrating orifice generator, monodisperse NaCl and DOP (di-octyl phthalate) aerosols generated by an electrostatic classification method, and sulfuric acid aerosols generated by the photo-chemical conversion of gaseous SO/sub 2/ in the smog chamber. The experiments covered a particle size range of 0.0075 ..mu..m to 5.04 ..mu..m diameter. The corresponding range in Knudsen number (Kn = lambda/sub i//a, lambda/sub i/ = mean free path of ions, a = particle radius) was from 0.0056 to 3.86. The charging parameter, n/sub 0/t, was varied between 2.56 x 10/sup 6/ to 5.1 x 10/sup 7/ ion-s/cc, where n/sub 0/ is the concentration of ions and t is the charging time. Comparisons of the results with available aerosol charging theories indicate that there is reasonable agreement between the theory and experiment in the continuum regime (Kn > 1) and the transition regimes (Kn approx. or equal to 1), where the ion mean free path is no longer small in comparison with particle size, there is considerable discrepancy between the experimental data and available charging theories. A semi-empirical equation was developed which agrees well with the experimental data over the entire range of particle size and charging parameters covered in the experiments. Theoretical results are presented showing the distribution of charges on the particles as a function of particle size and the charging parameter n/sub 0/t. 70 figures, 24 tables, 112 references. (auth)« less