Date of Award
Master of Science (MS)
Dr. J. R. Saylor
Dr. P. Tallapragada
Dr. A R. Metcalf
Fog-and-tube scrubbers are employed to remove harmful ultrafine aerosols, such as Diesel particulate matter (DPM), from an airflow. The underlying principle of this removal process involves enlarging the aerosol particles by coagulating them with fog drops, which are subsequently eliminated through inertial impaction onto the tube wall. Previous research conducted by Tabor et al. (2021) demonstrated an increase in scavenging of ultrafine DPM particles, ranging from 11.5 nm to 154 nm, by as large as 45% over the no fog case. This finding is crucial in addressing the challenges associated with conventional filtration methods for capturing ultrafine particles.
The present study focuses on simulating the scavenging process within a fog-and-tube scrubber, considering various mechanisms including gravitational settling, turbulent diffusion, swirl, and coagulation of particles and drops. The simulations investigate the effectiveness of swirl and turbulence in particle scavenging by varying the intensity of swirl and turbulence, collectively through the Reynolds number and independently using individual enhancement factors for turbulence (T ) and swirl (S). The results reveal that the coagulation of particles with drops and the deposition of drops through inertial impaction onto the wall, facilitated by swirl or turbulent diffusion, play significant roles in the removal of particles. The simulation presented here shows that swirl results in better scavenging. Additionally, the Sherwood number, which represents mass transfer to the wall in the presence of drops, can be expressed as a function of T and S. Increasing either factor enhances the Sherwood number, and combined, they increase mass transfer.
Patel, Nisarg T., "Influence of Swirl and Turbulence in the Particle Removal Using Fog in a Pipe Flow" (2023). All Theses. 4156.