Modeling and Numerical Studies of Submicron particle Transport and Filtration with Monolith filters

Aerosol particle filtration is crucial for many industrial and air purification processes. Different types of aerosol particle filters has been developed and utilized in the past few decades. Monolith filter is a new type of filter that fabricated from a single piece of polymer material characterized with small holes on a thin film. Monolith filter has significant potential for submicron aerosol particle filtration, even though the filtration process with this class of filters has not been well studied. Modeling and analysis of transport and filtration process in monolith filters were studied in this thesis.;Based on the filtration process and the repeating geometric structure of a monolith filter, a single channel model and a single unit model were developed respectively, where the drag force, electrostatic force, and Brownian motion are considered as the major forces affecting particle motion. Using a single channel model or a single unit model, numerical studies were performed with Lagrangian particle tracking methodology and a Monte Carlo simulation. Filtration efficiency was estimated by statistics of a group of particles. Simulation results clearly showed a transition of particle capture mechanism from Brownian motion to direction interception when particle diameter increases, resulting with a most penetrating particle size of 100nm to 250nm.;A single unit model was modified and improved based on the comparison with experimental results. The comparison suggests that the original model of Brownian force underestimated particle's Brownian motion, and Van Der Waals force should be considered when a particle is approaching to the surface of a filter. The improved model showed a reasonable agreement with experimental results. The dependency of filtration efficiency on flow rates, channel diameter and applied electric charge on the filter were studied with the improved model.;A preliminary dimensionless study was performed. While an interception parameter characterizes the particle capture due to direct interception, two dimensionless parameters, dimensionless Brownian force and dimensionless electrostatic force, were derived from the dimensionless form of the particle motion equation to characterize the particle motion due to Brownian diffusion and electrostatic force. Simulations suggests that these two dimensionless parameters cannot determine the capture efficiency by themselves. However, it was verified that particle capture due to Brownian diffusion inside a circular channel is dependent on a deposition parameter. Comparison between numerical simulations and traditional asymptotic solutions show that the traditional asymptotic solutions underestimates the filtration efficiency.