paper_rv_98 - ROOMVENT 98 Conference, Stockholm DEPOSITION...

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ROOMVENT &98 Conference, Stockholm page 1 DEPOSITION AND RESUSPENSION OF PARTICLES: WHICH PARAMETERS ARE IMPORTANT P. Lengweiler 1 , P.V. Nielsen 2 , A. Moser 1 , P. Heiselberg 2 , H. Takai 3 1 Air±Climate Group, Research in Building Technology, ETH Z²rich, ETH Zentrum LOW, 8092 Z²rich, Switzerland 2 Department of Building Technology and Structural Engineering, Aalborg University, Sohngaardsholmsvej 57, 9000 Aalborg, Denmark 3 Department of Agricultural Engineering and Production Systems, Research Centre Bygholm, 8700 Horsens, Denmark ABSTRACT A new experimental set-up to investigate the physical process of dust deposition and resuspension on and from surfaces is introduced. Dust deposition can reduce the airborne dust concentration considerably. As a basis for developing methods to eliminate dust related problems in rooms, there is a need for better understanding of the mechanism of dust deposition and resuspension. With the presented experimental set-up the dust load on surfaces in a channel can be measured as a function of the environmental and surface conditions and the type of particles under controlled laboratory conditions. Results of a first series of measurements are shown. It is found that the surface orientation is the parameter which influences the dust load most. The measurements indicate that the air velocity has a non-linear influence and that high turbulence causes high dust load. KEYWORDS Air quality, deposition, measuring technique, particles, resuspension. INTRODUCTION Indoor air contains particles which can affect the health of people. To study the health risk of a room it is necessary to find out which kind of particles are suspended in the air, where they come from and how they are transported and distributed in the air. According to Goddard et al. (1996), airborne dust concentration can be reduced significantly by deposition on surfaces. Therefore the physical process of deposition and resuspension has to be well understood before predictions of the health risk in a room are attempted by e.g. Computational Fluid Dynamics simulations (CFD). A large number of experiments and CFD simulations are reported in the literature to describe type and size of particles, sources of the particles and their distribution and transportation in the air. But only in a few experiments deposition is considered and in even fewer resuspension. To the authors knowledge, the existing CFD models contain no or only a very simple model for the deposition, e.g. 100 % deposition on floors and none on walls and ceilings. And many authors ignore resuspension altogether.
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ROOMVENT &98 Conference, Stockholm page 2 In order to improve these models, the deposition and the resuspension have to be defined as a function of the environmental and surface conditions and the type of particles as showed in Equations (1) and (2).
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This note was uploaded on 05/06/2010 for the course PHAST 1 taught by Professor Donck during the Spring '10 term at École Normale Supérieure.

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paper_rv_98 - ROOMVENT 98 Conference, Stockholm DEPOSITION...

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