Particle size aerosol distribution

Busigin, A., A.W. van der Vooren and C.R. Phillips, A Technique for Calculation of Aerosol Particle Size Distributions from Indirect Measurements, J. Aeros. Sci. 11 359-366 (1980). 

FIGURE 9.23 (a) Aerosol particle size distribution measured at Pomona during the 1972 State of California Air Resources Board ACHEX program, (b) Calculated optical scattering by particles, bsp, for measured size distribution (adapted from Waggoner and Charl-son, 1976). 

Molecular clusters can be considered to be the smallest size range of an aerosol particle size distribution. Nucleation from the gas phase to particles or droplets involves, in the initial stages, the formation of clusters. Research on clusters provides a valuable approach to understanding, on a molecular level, the details of the transfer of molecules from the gaseous to the condensed state by either new particle formation or heterogeneous processes including adsorption onto or dissolution into particles. 

Acridine char nitrogen, retention as function of burnoff, 307/, 308/ Advection fluxes, calculation, 41-43 Aerosol particle size distribution, molecular clusters, 317 Aerosol scavenging pathway, acetic and formic acid formation, 223 Aerosol species, transformation over the western Atlantic, 52 Aerosol sulfate airborne determination, 298 See also Sulfate... 

Other experiments have shown that the drug formulation affects the aerosol particle size distribution of a powder. Using the same DPI (i.e., Easyhaler), Steckel et al. reported that 19.9% of the mass of beclomethasone aerosol was <6.4 jm, while 36% of the mass of salbutamol was <6.4 jm (84). 

Everard ML, Devadason SG, LE Souef PN. Flow early in the inspiratory manoeuvre affects the aerosol particle size distribution from a Turbuhaler. Resp in Med 1997 91 624-628. 

Monodisperse primary particles in pMDIs show a significantly narrower aerosol particle size distribution than pMDIs containing poly disperse primary particles. A narrow size distribution is crucial to achieve a very fine particle fraction (49.31 8.16%) for primary particles greater than 2jim. 

Gravitational collisions between particles can be quite an important mechanism of coagulation in reactor containments because of the nature of the aerosol particle size distribution that develops in the containment atmosphere. Such size distributions are often predicted to be bimodal when there is an operating source of aerosol to the containment. The small size mode of the bimodal distribution is produced by particles freshly injected into the atmosphere from the operating source. The larger size mode is made up of particles that have aged in the atmosphere. Once sources of aerosol to the containment become small, the size distribution quickly becomes unimodal. 

Data obtained from the Si02 aerosol nanoparticle reactor and classification and detection systems are tabulated in Table 6.7. As shown in Table 6.7, by changing two main process conditions, namely Qpr and Tfurm the aerosol particle size distribution can be varied to produce particles from 7 run < dso <45 run at concentrations 10 -10 particles/cm, depending upon reactor configurations and tubing details. 

The extent of particle loss was assessed by comparing the aerosol particle size distribution entering the aerosol chamber and the particle size distribution exiting the aerosol chamber as a function of several process and experimental parameters. Representative particle size distributions are shown in Figure 6.21 below illustrating loss of. smaller particles due to a combination of loss to fixed surfaces (decrease in number concentration at a fixed dp) and loss to coagulation with other aerosol particles (decrease in number concentration at a fixed dp) and creation of larger particles (increase in number concentration at a fixed dp). 

Diffusion losses of aerosol nanoparticles due to internal surface area of filter housing units and associated tubing can be quantitated by comparing aerosol particle size distributions obtained from an aerosol that follows different paths within the reactor. As shown in Figure 6.29, the solid circle data is the particle... 

The condensation particle counter battery measurements are complemented by aerosol particle size distribution measurements using a dual differential mobility particle sizer system covering a size range of 3-900 nm, and an aerodynamic particle sizer covering aerosol particle sizes between 0.7 and 20 pm. In addition, air ions are detected using a balanced scanning mobility analyser and an air ion spectrometer. During the period of measurements, several new particle formation (nucleation) events occur in tropospheric air. 

Appendix 2 Theoretical Basis for Aerosol Particle Size Distributions / 105... 

The preceding sections have focused on the properties of distributions in general without considering any particular type of distribution. In this section, we describe the characteristics and applications of the lognormal distribution for aerosol particle size analysis. As discussed below, the normal distribution, although widely used elsewhere, is not suitable for most aerosol particle size distributions. 

The normal distribution function is rarely used to describe aerosol particle size distributions because most aerosols exhibit a skewed (long tail at large sizes) distribution function. The normal distribution is, of course, synunetrical. It can be applied to monodisperse test aerosols, to certain pollens and spores, and to specially prepared polystyrene latex spheres. The number frequency function is given by... 

APPENDIX 2 THEORETICAL BASIS FOR AEROSOL PARTICLE SIZE DISTRIBUTIONS... 

Most aerosol particle size distributions are skewed, so that relatively few large particles are present. To count a meaningful number of large particles involves counting unnecessarily large numbers of small particles. This problem can be... 

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