Turbulent deposition and gravitational sedimentation of an aerosol in a vessel of arbitrary shape

Crump, James G.; Seinfeld, John H.

doi:10.1016/0021-8502(81)90036-7

Cited by 251 publications

(209 citation statements)

References 3 publications

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“…The used friction velocity here is 1 cm/s. According to Lai and Nazaroff (2000) their model agrees with Crump And Seinfield (1981) model with parameters n=2.94 and k e = 0.0305 cm -0.94 s -1 , when friction velocity 1 cm/s is used.…”

Section: E-06mentioning

confidence: 65%

Fungal spore transport through a building structure

Airaksinen¹,

Kurnitski²,

Pasanen

et al. 2004

Indoor Air

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The study carried out laboratory measurements with a full-scale timber frame structure to determine penetration of inert particles with size distribution from 0.6 to 4 µm and spores of Penicillium and Cladosporium through the structure. Pressure difference over and air leakage through the structure were varied. Measurements at moderate pressure differences resulted in the penetration factors within the range of 0.05 to 0.2 for inert particles, and indicated also the penetration of fungal spores through the structure. The measurements showed that the penetration was highly dependent on pressure difference over the structure but not on holes in surface boards of the structure. The results show that surface contacts between the frames and mineral wool may have a significant effect on penetration. The penetration was approximately constant within particle size rage of 0.6-2.5 µm, but particles with diameter of 4.0 µm did not penetrate through the structure at all even at a higher-pressure difference of 20 Pa, except in the case of direct flow-path through the structure. Results have important consequences for practical design showing that penetration of fungal spores through the building envelope is difficult to prevent by sealing. The only effective way to prevent penetration seems to be balancing or pressurizing the building. In cold climates, moisture condensation risk should be taken into account if pressure is higher indoors than outdoors. Determined penetration factors were highly dependent on the pressure difference. Mechanical exhaust ventilation needs a special consideration as de-pressurizing the building may cause health risk if there is hazardous contamination in the building envelope exists. PRACTICAL IMPLICATIONSMeasurements at moderate pressure differences allowed determining penetration factors within the range of 0.05 to 0.2 for inert particles in a size range of 0.6-2.5 µm and indicative results with fungal spores confirmed the penetration through the wooden floor structure. Both measurements showed that the penetration was highly dependent on pressure difference and not dependent on holes in surface boards of the structure. The results are likely to show that surface contacts of mineral wool with other building elements may have an important role on the penetration.

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Section: E-06mentioning

confidence: 65%

Fungal spore transport through a building structure

Airaksinen¹,

Kurnitski²,

Pasanen

et al. 2004

Indoor Air

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“…This would result in a variation of the particle wall loss rate of the order of a factor of 1.5 at most, for any realistic size distribution. 18 This is similar or smaller than the uncertainty in other parameters. Because the structures of LVOC are relatively similar to IEPOX (and do not contain double bonded carbon atoms), the loss rate for LVOC via reaction with OH is assumed to be similar to those of IEPOX with OH (0.8 -1.5 ×10 -11 cm 3 molec -1 s -1 , isomer-dependent).…”

Section: No 3 --Cims Quantificationmentioning

confidence: 68%

Formation of Low Volatility Organic Compounds and Secondary Organic Aerosol from Isoprene Hydroxyhydroperoxide Low-NO Oxidation

Krechmer

Coggon

Massoli

et al. 2015

Environ. Sci. Technol.

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Gas-phase low volatility organic compounds (LVOC), produced from oxidation of isoprene 4-hydroxy-3-hydroperoxide (4,3-ISOPOOH) under low-NO conditions, were observed during the FIXCIT chamber study. Decreases in LVOC directly correspond to appearance and growth in secondary organic aerosol (SOA) of consistent elemental composition, indicating that LVOC condense (at OA below 1 μg m–3). This represents the first simultaneous measurement of condensing low volatility species from isoprene oxidation in both the gas and particle phases. The SOA formation in this study is separate from previously described isoprene epoxydiol (IEPOX) uptake. Assigning all condensing LVOC signals to 4,3-ISOPOOH oxidation in the chamber study implies a wall-loss corrected non-IEPOX SOA mass yield of ∼4%. By contrast to monoterpene oxidation, in which extremely low volatility VOC (ELVOC) constitute the organic aerosol, in the isoprene system LVOC with saturation concentrations from 10–2 to 10 μg m–3 are the main constituents. These LVOC may be important for the growth of nanoparticles in environments with low OA concentrations. LVOC observed in the chamber were also observed in the atmosphere during SOAS-2013 in the Southeastern United States, with the expected diurnal cycle. This previously uncharacterized aerosol formation pathway could account for ∼5.0 Tg yr–1 of SOA production, or 3.3% of global SOA.

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“…Brown diffusion dominates for the small particle, which results in the distribution of indoor particles uniform, and the deposition rate low. Large size particles are not evenly distributed in the interior due to obviously affected by gravity, hence the distribution in the lower part of the room is more and the deposition rate is higher [15,17,18]. …”

Section: The Particle Attenuation Index Of Different Air Exchange Ratementioning

confidence: 99%

The transmission characteristics of indoor particles under different ventilation conditions

Wang

Wei

2017

E3S Web Conf.

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Abstract:In modern society, ventilation is an important method for removing indoor particles. This study applies the parameter of attenuation index to analyze the effect of the removal of indoor particles in the two typical ventilation strategies called ceiling exhaust and slit exhaust strategy. Experiment was conducted in a chamber and riboflavin particles were used as the indoor particles source, instantaneous microbial detection (IMD) used to measure the particulate concentration. Conclusions can be found that air exchange rate is an important factor affecting the indoor particle concentration distribution. In the process of indoor free settling(air exchange rate is 0 h -1 ), the deposition rate were 0.086 h -1 , 0.122 h -1 , 0.173 h -1 for the particles of 0.5-1.0 μm, 1.0-3.0μm and 3.0-5.0 μm. When the air exchange rate increased to 2.5 h -1 , the differences in the attenuation index is significant. There was also a significant linear relationship between air exchange rate and attenuation index. Furthermore, the effect of the slit exhaust strategy on the removal of coarse particles is more remarkable as the increasing air exchange rate.

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Turbulent deposition and gravitational sedimentation of an aerosol in a vessel of arbitrary shape

Cited by 251 publications

References 3 publications

Fungal spore transport through a building structure

Fungal spore transport through a building structure

Formation of Low Volatility Organic Compounds and Secondary Organic Aerosol from Isoprene Hydroxyhydroperoxide Low-NO Oxidation

The transmission characteristics of indoor particles under different ventilation conditions

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