Bipolar diffusion charging of spheres and agglomerate aerosol particles

Rogak, Steven N.; Flagan, Richard C.

doi:10.1016/0021-8502(92)90037-v

Cited by 50 publications

(62 citation statements)

References 41 publications

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“…Aggregates were found to have a lower neutral fraction than spherical particles, which is consistent with previous studies (Rogak and Flagan 1992) and is well characterized by Lall and Friedlander's theory. The difference is also found to be a function of particle morphology.…”

Section: Resultssupporting

confidence: 91%

“…Figure 6a shows that the neutral fraction of diesel aggregates agrees very well with that proposed by Lall and Friedlander's theory (average relative deviation 4.2%). Diesel aggregates are about 7% more charged than spheres in terms of total charge fraction, which is consistent with the 5% value reported elsewhere (Rogak and Flagan 1992). Figure 6b shows that when silver particles are spherical (sintering temperature 600…”

Section: Charge Distribution Of Spherical Particlessupporting

confidence: 90%

“…Wen et al (1984a) introduced the concept of the charging equivalent diameter for bipolar charging, and Wen et al (1984b) found good agreement of experimental results with Boltzmann charge distribution in terms of neutral fraction when using charge equivalent diameter derived for conducting prolate spheroids. Rogak and Flagan (1992) showed that the neutral fraction was ∼5% lower for aggregates than for spheres in the mobility size range of 100-800 nm. However, none of them measured specific charge state distributions that are necessary to convert number-mobility distributions to concentration-size distributions.…”

Section: Introductionmentioning

confidence: 99%

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Bipolar Diffusion Charging of Aggregates

Xiao

Swanson

Pui

et al. 2012

Aerosol Science and Technology

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In this paper, the effect of particle morphology on bipolar diffusion charging is studied. A modified tandem differential mobility analyzer (TDMA) method used to measure the charge distribution of submicron particles in the range of 70-300 nm is described in detail. The method requires an independent measurement of the neutral fraction, followed by the measurement of the size-dependent charge distribution, which requires the knowledge of the neutral fraction. The method was validated experimentally using dioctyl sebacate and ammonium sulfate spherical particles and compared with Fuchs' theory. Diesel particles and silver aggregates were used to evaluate the impact of morphology on charging. The results show that aggregates have a slightly lower (about 7%) neutral fraction than spheres. These results are in agreement with the predictions of Lall and Friedlander's theory and previous studies. However, results from charge distribution indicate that more (about 46%) particles are negatively charged than predicted by Lall and Friedlander's theory, while 32% fewer particles are positively charged. This relatively large asymmetry between the negative and the positive charge fraction is not fully predicted by either Fuchs' or aggregate charging theories. Our results suggest that the current inversion method of scanning mobility particle sizer (SMPS) data, based on Fuchs' or Lall and Friedlander's distribution, would underestimate the total number concentration by about 15% or 27% if applied to diesel aggregates.

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Section: Resultssupporting

confidence: 91%

Section: Charge Distribution Of Spherical Particlessupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

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Bipolar Diffusion Charging of Aggregates

Xiao

Swanson

Pui

et al. 2012

Aerosol Science and Technology

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“…Rogak and Flagan (1992) pointed out that the differences among theories are more pronounced for smaller particles, although other measurements (Adachi et al 1985) support using Fuchs charging theory for smaller particle sizes (≤50 nm). Filippov (1993) carried out the comparison between Fuchs charging theory and Monte Carlo simulation.…”

Section: Diffusion Chargingmentioning

confidence: 92%

“…Among diffusion charging theories, Fuchs (1963) model is widely accepted for particles larger than 50 nm in diameter (Rogak and Flagan 1992). Rogak and Flagan (1992) pointed out that the differences among theories are more pronounced for smaller particles, although other measurements (Adachi et al 1985) support using Fuchs charging theory for smaller particle sizes (≤50 nm).…”

Section: Diffusion Chargingmentioning

confidence: 99%

Characterization of Aerosol Surface Instruments in Transition Regime

Jung

Kittelson

2005

Aerosol Science and Technology

105

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The primary purpose of this study is to measure the size-and composition-dependent responses of aerosol surface instruments designed to measure surface area related properties. The secondary purpose of this study is to investigate the difference in charging rate between singlets (NaCl particles) and agglomerates (diesel particles) by using diffusion chargers. Agglomerates (diesel particles at engine load 75%) acquire more charge than singlets (NaCl particles) by 15 and 17% for LQ1-DC and EAD, respectively.

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