Particle morphology and density characterization by combined mobility and aerodynamic diameter measurements. Part 1: Theory
Particle morphology and density characterization by combined mobility and aerodynamic diameter measurements. Part 1: Theory
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DOI：
10.1080/027868290903907
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发表时间：
2004-12-01
影响因子：
5.2
通讯作者：
Jimenez, JL
中科院分区：
文献类型：
--
作者：
DeCarlo, PF;Slowik, JG;Jimenez, JL
不同的在线亚微米粒度技术报告不同的“等效直径”。例如，差分迁移率分析仪（DMAs）报告电迁移率直径（d(m)），而许多最近开发的仪器（如Aerodyne气溶胶质谱仪或AMS）测量真空气动直径（d(va)）。颗粒密度和物理形态（形状）对直径测量有重要影响。本文提出了一个框架，将不同等效直径测量的信息内容组合成一个单一的粒子相干数学描述。我们首先介绍了文献中使用的数学公式及其关系。然后，我们表明结合d(m)和d（va）测量相同的粒子种群允许对粒子密度、动态形状因子（Chi）和内部空隙空间的分数施加约束。显示了从不同粒子类型的d(m)和d（va）测量组合可以推断出的信息量。通过额外的测量和/或一些假设，可以确定所有相关参数。具体地说，如果粒子密度已知并且有一个关于的假设，则可以通过dm和dva测量来确定粒子质量。是由。即使不知道Chi和密度，也可以仅从d(m)和d（va）测量中估计出大约2倍的粒子质量。在一定条件下，分形粒子的质量也可以估计出来。文献中对“有效密度”的各种定义的意义都放在理论的语境中。这一理论框架是应用于测量分形（烟灰样）粒子使用实验结果从文献作为额外的约束。
Different on-line submicron particle sizing techniques report different "equivalent diameters." For example, differential mobility analyzers(DMAs) report electrical mobility diameter (d(m)), while a number of recently developed instruments (such as the Aerodyne aerosol mass spectrometer, or AMS) measure vacuum aerodynamic diameter (d(va)). Particle density and physical morphology ( shape) have important effects on diameter measurements. Here a framework is presented for combining the information content of different equivalent diameter measurements into a single coherent mathematical description of the particles. We first present a review of the mathematical formulations used in the literature and their relationships. We then show that combining d(m) and d(va) measurements for the same particle population allows the placing of constraints on particle density, dynamic shape factor (Chi), and fraction of internal void space. The amount of information that can be deduced from the combination of d(m) and d(va) measurements for various particle types is shown. With additional measurements and/or some assumptions, all relevant parameters can be determined. Specifically, particle mass can be determined from dm and dva measurements if the particle density is known and an assumption about. is made. Even if Chi and density are not known, particle mass can be estimated within about a factor of 2 from d(m) and d(va) measurements alone. The mass of a fractal particle can also be estimated under certain conditions. The meaning of various definitions of "effective density" used in the literature is placed in the context of the theory. This theoretical framework is applied to measurements of fractal (soot-like) particles by using experimental results from the literature as additional constraints.