Nonequilibrium bipolar charging of aerosol particles: Theory and experiment

Fjeld, Robert A.; Heinsohn, Robert Jennings; Levine, S.H.

doi:10.1016/0021-9797(77)90066-2

Cited by 6 publications

(5 citation statements)

References 11 publications

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“…, and parameter r1 therewith plays a'role of dimensionless time T of particle charging, so that T -r1 (cf., Fjeld et al 1977Fjeld et al , 1981Fjeld et al , 1983). If p < < 1 (the case of strong electric fields),…”

Section: Aerosol Charging In An Alpha-radiation Chargermentioning

confidence: 99%

“…As a result, fine particles acquire a charge in the non-uniform atmosphere of positive ions and electrons in different charging regimes (the continuum regime in the case of ions and the free-molecular or transition regime in the case of electrons); in this situation the "field charging" mechanism of capture of nonthermal electrons can be neglected (Dubard et al 1983, O'Hara et al 1989, Zagnit'ko et al 1989. Some cases of aerosol particle charging in the bipolar ionic atmosphere of electronegative gases in the presence of electric field were considered earlier (e.g., Hoppel and Garthman 1970, Withers et al 1978, Stechkina et al 1982, and in greater detail by Fjeld et al (1977Fjeld et al ( , 1981Fjeld et al ( , 1983Fjeld et al ( , 1986 and Wu et al (1987). However, it is just recently that fine particle charging in the non-uniform atmosphere of positive ions and nonthermal electrons of electropositive gases has begun to draw researchers' attention (Wiedensohler and Fissan 1988;Zagnit'ko et al 1989Zagnit'ko et al , 1992Zagnit'ko et al , 1993Pui 1992a and1992b).…”

Section: Introductionmentioning

confidence: 99%

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Aerosol Chargers Using Ionizing Radiation and Electric Field Collinear to Flow: Simulation and Experiment for Fine Particle Charging in Electronegative Air and Electropositive Nitrogen

Фомичев

Trotsenko

Загнитько

1997

Aerosol Science and Technology

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Section: Aerosol Charging In An Alpha-radiation Chargermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Aerosol Chargers Using Ionizing Radiation and Electric Field Collinear to Flow: Simulation and Experiment for Fine Particle Charging in Electronegative Air and Electropositive Nitrogen

Фомичев

Trotsenko

Загнитько

1997

Aerosol Science and Technology

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“…Analysis of the relationship between vehicle CO emissions and ambient CO concentrations by a generalized rollback model predicts, however, that a CO VES of 11-12 g/mi would achieve the 9 ppm AQS for CO. 1 tion. 5 It would follow therefore that the 9 g/mi VES for CO recommended by a California Air Resources Board staff report 6 would be sufficient to achieve the CO AQS and that the Federal 3.4 g/mi VES for CO is unnecessarily severe.…”

Section: Ford Motor Companymentioning

confidence: 99%

“…It should be possible to apply the methodology used in the generalized rollback model 1 to derive weighting factors for CO emissions data obtained with the present FTP to give revised CO emission factors that correlate with the downtown urban CO problem. The derivation of the desired weighting factors is the purpose of this paper (1) where Bi (Bag 1), B 2 (Bag 2), and B 3 (Bag 3) are the measured grams per test for each of the three bags, respectively. The Bag 1 and Bag 3 tests cover 3.59 mi and Bag 2 covers 3.91 mi.…”

Section: Ford Motor Companymentioning

confidence: 99%

“…When there is atmospheric stagnation, 7 is relatively large because C; makes a much greater contribution to C than does C a . In the generalized rollback model, 1 7 was taken as 10 to correspond to extreme meteorological conditions likely to prevail when the annual maximum CO concentration is observed. If the air quality standard were defined to be statistically more meaningful (e.g., the 99th percentile) than the single annual maximum value, 4 then, the corresponding choice of 7 would be 4.…”

Section: Revised Ftp Weighting Factorsmentioning

confidence: 99%

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Revised Weighting of CVS/CH Test Results for CO Vehicle Emission Factors

Chang

Weinstock

1978

Journal of the Air Pollution Control Association

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APCA NOTE-BOOKat 10 to 15 min after the dust feed system was turned on. Extremely large fluctuations in the screen current are evidence of a high level of back corona activity.The notation Q/m on Figure 2 indicates the interval of time during which a measurement of particle charging effectiveness was made. Particles were collected on a silver mesh filter mounted in a plastic filter holder, fitted with a nozzle for isokinetic sampling. The filter was connected to an electrometer so that the charge accumulation could be monitored during the collection process. A foil shield, grounded through a 10 megohm resistor was wrapped around the body of the filter holder to prevent buildup of charge on the insulating plastic. Upon completion of the sampling period, the total accumulated charge was recorded and the captured dust sample was weighed. These data were then used to calculate the ratio of charge to mass Q/m for the sample.In the experiment associated with Figure 2, the measured value of Q/m was approximately 2.9 fiC/g. Theoretical values of charge for the particle distribution used in this test showed good agreement with the experimental value. Since the theory is based on charging by unipolar ions, it appears that back corona suppression by the action of the screen electrode was successful. Without the screen grid the corona current density at the plate would be limited to the level at which back corona occurs. That value would be of the order of 1% of the corona current used in the experiment above.Experiments with a device similar to the new precharger, but lacking the corona suppression screen, provide for a comparison with the conventional technology.2 Maximum charging levels for low resistivity dusts (<10 10 ohm cm) in the "conventional" device are three to five times greater than those achieved in the high resistivity experiments with the new precharger. But when a high resistivity dust was introduced into the "conventional" device the measured charge to mass ratio dropped to a value less than one tenth of that measured with a similar dust in the new precharger. The new device thus provides a significant advantage where back corona is a problem. SummaryThe aerosol precharger described in the preceding paragraphs can provide a charging environment with relatively high unipolar ion density for particulate matter having high electrical resistivity. The result is a much higher level of charge on the particles than can be achieved by a conventional electrostatic precipitator which is limited by back corona to a low current density.3 Used in conjunction with a downstream collector operated at a low current density and high electric field strength, the precharger may be of significant value in the collection of high resistivity particulate materials. The statutory Federal Vehicle Emission Standard (VES) of 3.4 g/mi for carbon monoxide (CO) is intended to achieve the National Ambient Air Quality Standard (AQS) for CO of 9 ppm, 8 hour average. Analysis of the relationship between vehicle CO emissions and ambient CO c...

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Aerosol Charge Neutralization by a Radioactive Alpha Source

Liu

Pui

Lin

1986

Part & Part Syst Charact

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The performance of a Po-210 radioactive ionizer for aerosol charge neutralization and bipolar charging has been evaluated. Monodisperse neutral and singly charged aerosols have been passed through the ionizer and their approach to the steady-state Boltzmann charge measured by measuring the fraction of particles that are electrically charged. The result shows that an Nt of approximately 2.5 x lo5 cm -3 s is needed for the development of a steady-state charge fraction equal to that given by the Boltzmann's law where N is the ion concentration and f is the residence time of the aerosol in the neutralizer. In addition, the performance of the ionizer for particle charge neutralization in a vibrating-orifice aerosol generator has been evaluted and the result shows that the source is less effective for this application and the residual charge on the particles is considerably higher than that given by the Boltzmann's law.

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Nonequilibrium bipolar charging of aerosol particles: Theory and experiment

Cited by 6 publications

References 11 publications

Aerosol Chargers Using Ionizing Radiation and Electric Field Collinear to Flow: Simulation and Experiment for Fine Particle Charging in Electronegative Air and Electropositive Nitrogen

Aerosol Chargers Using Ionizing Radiation and Electric Field Collinear to Flow: Simulation and Experiment for Fine Particle Charging in Electronegative Air and Electropositive Nitrogen

Revised Weighting of CVS/CH Test Results for CO Vehicle Emission Factors

Aerosol Charge Neutralization by a Radioactive Alpha Source

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