Deposition of Suspended Particles from Turbulent Gas Streams

Friedlander, Sheldon K.; Johnstone, H. F.

doi:10.1021/ie50571a039

Cited by 561 publications

(220 citation statements)

References 5 publications

Supporting

Mentioning

203

Contrasting

Unclassified

Order By: Relevance

“…Particle throughput in a flow tube due to diffusion to the walls is taken into account by the penetration term, P = n out /n in , which is defined as the ratio of the particle concentration coming out of the cylindrical tube at a distance L (n out ) to that at distance L = 0 (n in ). Calculations of P for this system for either laminar (Hinds 1999) or turbulent flow regimes (Friedlander and Johnstone 1957;Wells and Chamberlain 1967;Lee and Gieseke 1994) show that even for the smallest particles sampled by SMPS (21 nm), particle loss by diffusion to the walls is ≤2% and represents a negligible loss for particles larger than 50 nm. Additionally, wall loss due to electrostatic effects which results in substantial particle deposition in Teflon chambers is not a problem in a metallic flow system (McMurry and Rader 1985).…”

Section: Flow Parametersmentioning

confidence: 97%

A New Aerosol Flow System for Photochemical and Thermal Studies of Tropospheric Aerosols

Ezell

Johnson

et al. 2010

Aerosol Science and Technology

View full text Add to dashboard Cite

For studying the formation and photochemical/thermal reactions of aerosols relevant to the troposphere, a unique, high-volume, slow-flow, stainless steel aerosol flow system equipped with UV lamps has been constructed and characterized experimentally. The total flow system length is 8.5 m and includes a 1.2 m section used for mixing, a 6.1 m reaction section and a 1.2 m transition cone at the end. The 45.7 cm diameter results in a smaller surface to volume ratio than is found in many other flow systems and thus reduces the potential contribution from wall reactions. The latter are also reduced by frequent cleaning of the flow tube walls which is made feasible by the ease of disassembly. The flow tube is equipped with ultraviolet lamps for photolysis. This flow system allows continuous sampling under stable conditions, thus increasing the amount Received 3 November 2009; accepted 10 January 2010. We are grateful to the U.S. Department of Energy (Grant # DE-FG02-05ER64000) for support of this work. Additional support was provided by the AirUCI Environmental Molecular Science Institute funded by the National Science Foundation (Grant # CHE-0431312). E.A.B. acknowledges financial support from a National Science Foundation graduate student fellowship. This research was in part in collaboration with the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the U.S. Address correspondence to Barbara J. Finlayson-Pitts, Department of Chemistry, University of California Irvine, Irvine, CA 92697-2025, USA. E-mail: bjfinlay@uci.edu of sample available for analysis and permitting a wide variety of analytical techniques to be applied simultaneously. The residence time is of the order of an hour, and sampling ports located along the length of the flow tube allow for time-resolved measurements of aerosol and gas-phase products. The system was characterized using both an "inert" gas (CO 2 ) and particles (atomized NaNO 3 ). Instruments interfaced directly to this flow system include a NO x analyzer, an ozone analyzer, relative humidity and temperature probes, a scanning mobility particle sizer spectrometer, an aerodynamic particle sizer spectrometer, a gas chromatograph-mass spectrometer, an integrating nephelometer, and a Fourier transform infrared spectrophotometer equipped with a long path (64 m) cell. Particles collected with impactors and filters at the various sampling ports can be analyzed subsequently by a variety of techniques. Formation of secondary organic aerosol from α-pinene reactions (NO x photooxidation and ozonolysis) are used to demonstrate the capabilities of this new system.

show abstract

Section: Flow Parametersmentioning

confidence: 97%

A New Aerosol Flow System for Photochemical and Thermal Studies of Tropospheric Aerosols

Ezell

Johnson

et al. 2010

Aerosol Science and Technology

View full text Add to dashboard Cite

show abstract

“…The disagreement seen near the bottom of the dip may be attributed to the adoption of the turbulentdiffusion coefficient for gas to what are in actuality suspended particles, and also to insufficiency of the model assumed to represent the mechanism of deposition from turbulent flow. However, even in the case of a rather rough pipe, the deposition fraction in the turbulent region can still be estimated by either of the two methods of calculation (Yoshioka et to" ro 5 Reynolds number (-l Experimental and calculated deposition fractions of particles with different diameters vs. flow velocity and Reynolds number…”

Section: L-f(l1)mentioning

confidence: 99%

Measurement of Deposition Fraction of Aerosol Particles in a Horizontal Straight Metal Pipe

Matsui

Yoshida

Murata

et al. 1974

Journal of Nuclear Science and Technology

View full text Add to dashboard Cite

Loss by deposition of aerosol particles in an air sampling pipe causes error in the estimation of aerosol concentration in the atmosphere.For a horizontal pipe, the deposition fraction for laminar flow can be estimated by equations of deposition governed by gravity settling and diffusion. For turbulent flow, there are two methods available-one using the equation by Yoshioka et al. to express deposition velocity, the other being the "extrapolation method" proposed by the present authors.The present paper examines the validity of the two methods, with particular reference to the contribution of gravity settling to the deposition, and the effect of roughness of the pipe wall on the deposition from turbulent flow.The deposition fraction in a horizontal straight metal pipe can be estimated with deviation from experimental values not exceeding a factor of 2, throughout the whole region covered by the study, extending over both laminar and turbulent ranges. Use of a suitable friction factor to account for the roughness of the pipe wall gives a reasonable value of deposition fraction in the turbulent region. The deposition from turbulent flow is mainly governed by gravity settling when the Reynolds number is not very large (Re:= 10 4 ).

show abstract

“…On the contrary, heavy particles are not so well correlated with turbulent structures and their motion is less influenced by them in the near-wall region. Therefore, heavy particles deposit with large wall-normal velocities and small near-wall residence time, that is by the so-called free-flight mechanism 10,13 .…”

Section: Introductionmentioning

confidence: 99%

Langevin PDF simulation of particle deposition in a turbulent pipe flow

Chibbaro

Minier

2008

Journal of Aerosol Science

View full text Add to dashboard Cite

The paper deals with the description of particle deposition on walls from a turbulent flow over a large range of particle diameter, using a Langevin PDF model. The first aim of the work is to test how the present Langevin model is able to describe this phenomenon and to outline the physical aspects which play a major role in particle deposition. The general features and characteristics of the present stochastic model are first recalled. Then, results obtained with the standard form of the model are presented along with an analysis which has been carried out to check the sensitivity of the predictions on different mean fluid quantities. These results show that the physical representation of the near-wall physics has to be improved and that, in particular, one possible route is to introduce specific features related to the near-wall coherent structures. In the following, we propose a simple phenomenological model that introduces some of the effects due to the presence of turbulent coherent structures on particles in a thin layer close to the wall. The results obtained with this phenomenological model are in good agreement with ex-1 perimental evidence and this suggests to pursue in that direction, towards the development of more general and rigorous stochastic models that provide a link between a geometrical description of turbulent flow and a statistical one.

show abstract

Deposition of Suspended Particles from Turbulent Gas Streams

Cited by 561 publications

References 5 publications

A New Aerosol Flow System for Photochemical and Thermal Studies of Tropospheric Aerosols

A New Aerosol Flow System for Photochemical and Thermal Studies of Tropospheric Aerosols

Measurement of Deposition Fraction of Aerosol Particles in a Horizontal Straight Metal Pipe

Langevin PDF simulation of particle deposition in a turbulent pipe flow

Contact Info

Product

Resources

About