Experimental analysis of particle concentration heterogeneity in a ventilated scale chamber

The mixing processes of the aerosol particles from an outdoor environment in a ventilated scale chamber were experimentally studied. The particles were classified into five groups by size: 0.3-0.5 mu m, 0.5-1.0 mu m, 1.0-3.0 mu m, 3.0-5.0 mu m and 5.0-10.0 mu m. The developing process for the concentration of each particle group was measured in different kinds of flow fields. The results show that the flow field configuration can effectively influence the dispersion time rate of the particles at certain positions. The increase in particle diameter can decrease the dispersion time rate. When the gas flow velocity is high, the particle dispersion time rate is independent of particle size; but when the gas flow velocity is low, particle size can significantly affect the particle dispersion time rate because the turbulent diffusion becomes important in the air and particle transport. The uniformity of the particle concentration for certain positions in steady state tends to be controlled by the inflow velocity, flow field configuration and the particle diameters. (C) 2009 Elsevier Ltd. All rights reserved