Experimental Methodology to Determine Absolute Particle Resuspension Fractions for Indoor Surfaces

BRANDON E. BOOR (1), Jeffrey A. Siegel (1), Atila Novoselac (1)

(1) The University of Texas at Austin

     Abstract Number: 562
     Last modified: May 13, 2010

Abstract
An experimental methodology was developed to determine absolute particle resuspension fractions (number of resuspended particles/initial particle surface concentration) for common indoor surfaces, such as various flooring materials and HVAC components. Material samples were seeded with a monolayer of fluorescent tracer particles with diameters ranging from 1 to 10 micrometers. To expose the seeded samples to a broad range of flow conditions found in indoor environments, a micro-scale wind tunnel was designed with the assistance of Computational Fluid Dynamics (CFD). The wind tunnel employs filtered, pressurized air as the driving mechanism for fluid flow to permit a more controlled means to sample resuspended particles. The wind tunnel also features an impinging jet manifold to generate high velocity air jets. A fluorescence stereomicroscope, along with morphometry software, was used to accurately count the number of resuspended particles. The microscopy data was then compared with data collected with an Aerodynamic Particle Sizer (APS) to assess the impact of particle deposition in the wind tunnel sample duct. Furthermore, the absolute resuspension fraction was correlated with the relative resuspension rate derived in a previous study at The University of Texas at Austin. Preliminary experiments have shown that the absolute particle resuspension fraction increases with increasing particle diameter, bulk air velocity, and turbulence intensity and that the relative resuspension rate can be adjusted by a correction factor to obtain an absolute resuspension fraction.