Deposition of Particles in a Chamber as a Function of Ventilation Rate

Nomura, Yoshio; Hopke, Philip K.; Fitzgerald, Bernard J.; Mesbah, Boualem

doi:10.1080/02786829708965458

Cited by 46 publications

(34 citation statements)

References 23 publications

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“…Originally the model did not include the gravitational sedimentation factor, thus, it is accurate only for small particles. However, a simple sedimentation term is added to their model by Nomura et al (1997), which extended the size range of particles in micrometer size range. The used parameter values, derived by Nomura et al (1997) were: k e = 1.66 s -1 , n=2.6.…”

Section: E-06mentioning

confidence: 99%

“…However, a simple sedimentation term is added to their model by Nomura et al (1997), which extended the size range of particles in micrometer size range. The used parameter values, derived by Nomura et al (1997) were: k e = 1.66 s -1 , n=2.6. The other theoretical model by Lai and Nazaroff (2000), also takes into account Brownian diffusivity, surface and volume areas, particle diameter and kinematic viscosity, but the describing parameter in the equation of deposition velocity is friction velocity u*.…”

Section: E-06mentioning

confidence: 99%

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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: 99%

Section: E-06mentioning

confidence: 99%

Fungal spore transport through a building structure

Airaksinen¹,

Kurnitski²,

Pasanen

et al. 2004

Indoor Air

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“…A review of previous research indicates that there are only a small number of studies (e.g., Shimada et al 1987;Nomura et al 1997;Thatcher et al 2001) of the effect of air ow parameters on aerosol decay or deposition in room-sized enclosures, and none of these address the direct measurement of aerosol deposition on small-scale roughness elements of the dimensions commonly found in wall-coverings (studies such as that of Fogh et al (1997) have compared aerosol decay deposition velocities in fully-furnished and unfurnished rooms). To address this, in the present work aerosol decay rates were determined for 4 particle sizes in a smooth-walled 8 m 3 test chamber, at a different fan speed to that studied by Byrne et al (1995) in the same chamber, so that the effect of fan speed on a size-speci c deposition rate could be observed.…”

Section: Introductionmentioning

confidence: 99%

Experimental Studies of the Effect of Rough Surfaces and Air Speed on Aerosol Deposition in a Test Chamber

Lai¹,

Byrne²,

Goddard³

2002

Aerosol Science and Technology

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Understanding the fate of particles indoors is important for human health assessment because deposited particles, unless resuspended, cannot be inhaled. To complement studies in real buildings, where control of variables is often dif cult, an experimental test chamber facility (8 m 3 ) was designed to study particle deposition under well-stirred conditions using monodisperse tracer aerosol particles in the range of 0.7 to 5.4 ¹m. The use of neutronactivatable tracers facilitated simultaneous surface sampling and aerosol concentration decay measurements.Aerosol deposition on both smooth surfaces and regular arrays of three-dimensional roughness elements under 3 different air ow speeds was investigated in the test chamber. It was expected that the texture of the chamber surface would signi cantly in uence particle deposition, but some counterintuitive results were observed: under the lowest air ow condition and for the smallest particle size, particle deposition onto rough samples was found to be less than on the corresponding smooth surfaces.The ratio of particle deposition on rough surfaces relative to smooth surfaces increased with particle size and magnitude of airow. For the largest particle size and air ow speed, particle deposition on the rough surfaces exceeded that on the smooth surfaces by a factor of 3.

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“…This review included 15 key indoor particle deposition references (Lai et al 2002;Thatcher et al 2002;Abadie et al 2001;Cheng 1997;Fogh et al 1997;Nomura et al 1997;Morawska and Jamriska 1996;Byrne et al 1995;Xu et al 1994;Chen et al 1992;Van Dingenen et al 1989;Okuyama et al 1986;Offermann et al 1985;Crump et al 1983;Harrison 1979). Lai's review includes graphs of deposition rate as a function of particle size as well as information regarding the experimental test conditions including test chamber dimensions, mixing mechanism, chamber type, and chamber surface textures.…”

Section: Particle Deposition Ratesmentioning

confidence: 99%

Database tools for modeling emissions and control of air pollutants from consumer products, cooking, and combustion

Howard-Reed¹,

Polidoro²

2006

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In order to estimate building contaminant concentrations and associated occupant exposures, indoor air quality (IAQ) model users require data related to source strengths and other contaminant transport mechanisms (e.g. sinks, filters). Much of this information exists in the literature; however, it is not readily accessible, thereby requiring users to expend significant efforts in searching for this information. To support the modeling process, the National Institute of Standards and Technology (NIST) has created a series of model input databases for use in its multizone IAQ and ventilation model CONTAM. As part of this effort, a standard data entry format was developed, as well as a computer program to search the database for specific records and build a CONTAM input library. These databases and tools can serve as a basis for building an extensive collection of model input parameters, assessing the quality and completeness of existing data sets, and allow for identification of significant data gaps.

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Deposition of Particles in a Chamber as a Function of Ventilation Rate

Cited by 46 publications

References 23 publications

Fungal spore transport through a building structure

Fungal spore transport through a building structure

Experimental Studies of the Effect of Rough Surfaces and Air Speed on Aerosol Deposition in a Test Chamber

Database tools for modeling emissions and control of air pollutants from consumer products, cooking, and combustion

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