Modeling particle dispersion and deposition in indoor environments

Abstract Particle dispersion and deposition in man-made enclosed environments are closely related to the well-being of occupants. The present study developed a three-dimensional drift-flux model for particle movements in turbulent indoor airflows, and combined it into Eulerian approaches. To account for the process of particle deposition at solid boundaries, a semi-empirical deposition model was adopted in which the size-dependent deposition characteristics were well resolved. After validation against the experimental data in a scaled isothermal chamber and in a full-scale non-isothermal environmental chamber, the drift-flux model was used to investigate the deposition rates and human exposures to particles from two different sources with three typical ventilation systems: mixing ventilation (MV), displacement ventilation (DV), and under-floor air distribution (UFAD). For particles originating from the supply air, a V-shaped curve of the deposition velocity variation as a function of particle size was observed. The minimum deposition appeared at 0.1– 0.5 μ m . For supermicron particles, the ventilation type and air exchange rate had an ignorable effect on the deposition rate. The movements of submicron particles were like tracer gases while the gravitational settling effect should be taken into account for particles larger than 2.5 μ m . The temporal increment of human exposure to a step-up particle release in the supply air was determined, among many factors, by the distance between the occupant and air outlet. The larger the particle size, the lower the human exposure. For particles released from an internal heat source, the concentration stratification of small particles (diameter < 10 μ m ) in the vertical direction appeared with DV and UFAD, and it was found the advantageous principle for gaseous pollutants that a relatively less-polluted occupied zone existed in DV and UFAD was also applicable to small particles.

[1]  K. Okuyama,et al.  Influence of particle inertia on aerosol deposition in a stirred turbulent flow field , 1989 .

[2]  Koichi Hishida,et al.  Experiments on particle dispersion in a turbulent mixing layer , 1992 .

[3]  A. Lai,et al.  Modeling particle distribution and deposition in indoor environments with a new drift–flux model , 2006 .

[4]  A. Mangili,et al.  Review Transmission , 2022 .

[5]  M. Sandberg,et al.  Building Ventilation: Theory and Measurement , 1996 .

[6]  Qingyan Chen,et al.  Floor-Supply Displacement Ventilation in a Small Office , 2003 .

[7]  G. Cass,et al.  Mass-transport aspects of pollutant removal at indoor surfaces , 1989 .

[8]  Y. Nomura,et al.  Deposition of Particles in a Chamber as a Function of Ventilation Rate , 1997 .

[9]  E. Loth Numerical approaches for motion of dispersed particles, droplets and bubbles , 2000 .

[10]  Preventing Mold by Keeping New Construction Dry , 2002 .

[11]  E. Loth Eulerian Model for Mean Turbulent Diffusion of Particles in Free Shear Layers , 1998 .

[12]  T. L. Thatcher,et al.  Particle Deposition from Natural Convection Enclosure Flow Onto Smooth Surfaces , 1996 .

[13]  M. L. Laucks,et al.  Aerosol Technology Properties, Behavior, and Measurement of Airborne Particles , 2000 .

[14]  Qingyan Chen,et al.  Experimental measurements and numerical simulations of particle transport and distribution in ventilated rooms , 2006 .

[15]  E. Nardell,et al.  Exogenous reinfection with tuberculosis in a shelter for the homeless. , 1986, The New England journal of medicine.

[16]  John Burnett,et al.  Influence of Different Indoor Activities on the Indoor Particulate Levels in Residential Buildings , 1998 .

[17]  P. Moin,et al.  Turbulence statistics in fully developed channel flow at low Reynolds number , 1987, Journal of Fluid Mechanics.

[18]  Bin Zhao,et al.  Modeling particle deposition from fully developed turbulent flow in ventilation duct , 2006 .

[19]  G. McDonell Underfloor & displacement: why they're not the same , 2003 .

[20]  Np P. Gao,et al.  Investigating Indoor Air Quality and Thermal Comfort Using a Numerical Thermal Manikin , 2007 .

[21]  David L. Swift,et al.  THE MEASUREMENTS OF HUMAN INHALABILITY OF ULTRALARGE AEROSOLS IN CALM AIR USING MANNIKINS , 1999 .

[22]  William C. Hinds,et al.  Inhalability of large solid particles , 2002 .

[23]  Alvin C.K. Lai,et al.  Modeling Indoor Particle Deposition from Turbulent Flow onto Smooth Surfaces , 2000 .

[24]  Tracy L. Thatcher,et al.  Effect of Small-Scale Obstructions and Surface Textures on Particle Deposition from Natural Convection Flow , 1997 .

[25]  P V Nielsen,et al.  Role of ventilation in airborne transmission of infectious agents in the built environment - a multidisciplinary systematic review. , 2007, Indoor air.

[26]  Lidia Morawska,et al.  Particle deposition rates in residential houses , 2005 .

[27]  W. Nazaroff Indoor particle dynamics. , 2004, Indoor air.

[28]  S. Aggarwal,et al.  A Numerical Investigation of Particle Deposition on a Square Cylinder Placed in a Channel Flow , 2001 .

[29]  Sture Holmberg,et al.  Modelling of the Indoor Environment – Particle Dispersion and Deposition , 1998 .

[30]  Brian G. Miller,et al.  Aerosol inhalability at higher windspeeds , 1990 .

[31]  Fred S P.E. Bauman,et al.  Task/ambient conditioning systems: Engineering and application guidelines - eScholarship , 1996 .

[32]  Andrew D. Maynard,et al.  Aerosol inhalability in low air movement environments , 1999 .

[33]  L. Wallace,et al.  Indoor particles: a review. , 1996, Journal of the Air & Waste Management Association.