AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Agglomerate and Spherical Nanoparticle Penetration Through Nuclepore Filters: Models and Experiment
SHENG-CHIEH CHEN, Jing Wang, Heinz Fissan, David Pui, University of Minnesota
Abstract Number: 234 Working Group: Aerosol Physics
Abstract Nanotechnology is being developed rapidly in the past decade leading to a potential increase of engineered nanosized and submicron particles release to atmosphere as well as in workplaces. To better understand the toxicity of these small particles, Cyrs et al. (2010) conducted nuclepore filter collection with a further electron microscopy analysis to measure particle number and surface area concentrations which have been shown to associate closely with adverse health effects. The existing models such as Spurny et al. (1969) and Manton (1978) were usually used to predict the particle penetration and then provided the information for selecting a nuclepore filter with an appropriate pore size to minimize the pressure drop. In these models, particle size was one of important parameters of penetration when they were always assumed to be spherical particles. However some of these released particles are in the shape of chain-like agglomerates. For example, particles are released from welding process, CNT manufacturing, nanopodwer manufacturing and so on. Besides, penetration characteristic of agglomerates across filters is different from those of spheres with the same mobility diameter due to the difference of dynamics. To understand the difference of filtration penetration between spherical particles and agglomerates, penetrations of silver spheres and loose agglomerates, soot agglomerates, spherical PSL and cubic NaCl through Nuclepore filter were studied experimentally. The data were compared with the existing models for spheres firstly for validating the models. Then a modified fractal dimension prediction model was developed and used to predict particle effective length with different fractal agglomerates for calculating their penetrations. Good agreement between the data and model was found for various filtration operation conditions in terms of face velocity, pore diameter, particle density and particle fractals.