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- Genre: Masters Thesis
Description
Maricopa County has exceeded the 24 hour National Ambient Air Quality Standard (NAAQS) for Particulate Matter 10 micrometers in diameter or smaller (PM-10) of 150 micrograms per meter cubed (μg/m3) since 1990. Construction and construction related activities have been recognized as the highest contributors to high PM-10 levels. An analysis of days exceeding 150 μg/m3 for four of Maricopa County‟s monitors that most frequently exceed this level during the years 2007, 2008, and 2009 has been performed. Noted contributors to PM-10 levels have been identified in the study, including earthmoving permits, stationary source permits, vacant lots, and agriculture on two mile radius maps around each monitor. PM-10 levels and wind speeds for each date exceeding 225 μg/m3 were reviewed to find specific weather or anthropogenic sources for the high PM-10 levels. Weather patterns for days where multiple monitors exceed 150 μg/m3 were reviewed to find correlations between daily weather and high PM-10 levels. It was found that areas with more earthmoving permits had fewer days exceeding 150 μg/m3 than areas with more stationary permits, vacant lots, or agriculture. The Higley and Buckeye monitors showed increases in PM-10 levels when winds came from areas covered by agricultural land. West 43rd Avenue and Durango monitors saw PM-10 rise when the winds came in over large stationary sources, like aggregate plants. A correlation between weather events and PM-10 exceedances was also found on multiple monitors for dates both in 2007, and 2009.
ContributorsCook, Heloise (Author) / Olson, Larry (Thesis advisor) / Brown, Albert (Committee member) / Hristovski, Kiril (Committee member) / Arizona State University (Publisher)
Created2011
Description
The current work aims to understand the influence of particles on scalar transport in particle-laden turbulent jets using point-particle direct numerical simulations (DNS). Such turbulence phenomena are observed in many applications, such as aircraft and rocket engines (e.g., engines operating in dusty environments and when close to the surface) and geophysical flows (sediment-laden rivers discharging nutrients into the oceans), etc.This thesis looks at systematically understanding the fundamental interplay between (1) fluid turbulence, (2) inertial particles, and (3) scalar transport. This work considers a temporal jet of Reynolds number of 5000 filled with the point-particles and the influence of Stokes number (St). Three Stokes numbers, St = 1, 7.5, and 20, were considered for the current work. The simulations were solved using the NGA solver, which solves the Navier-Stokes, advection-diffusion, and particle transport equations.
The statistical analysis of the mean and turbulence quantities, along with the Reynolds stresses, are estimated for the fluid and particle phases throughout the domain. The observations do not show a significant influence of St in the mean flow evolution of fluid, scalar, and particle phases. The scalar mixture fraction variance and the turbulent kinetic energy (TKE) increase slightly for the St = 1 case, compared to the particle-free and higher St cases, indicating that an optimal St exists for which the scalar variation increases. The current preliminary study establishes that the scalar variance is influenced by particles under the optimal particle St. Directions for future studies based on the current observations are presented.
ContributorsPaturu, Venkata Sai Sushant (Author) / Pathikonda, Gokul (Thesis advisor) / Kasbaoui, Mohamed Houssem (Committee member) / Kim, Jeonglae (Committee member) / Prabhakaran, Prasanth (Committee member) / Arizona State University (Publisher)
Created2023
Description
The current research is based on the principles of three-dimensional discrete element method (3D – DEM) through simulations, by using heat transfer models in EDEM, to investigate the effects of fill level, rotation rate and particle size on the steady-state conduction heat transfer in rotary drums. The high heat and mass transfer rates obtained through rotary drums make them very useful for powder mixing and heating processes in metallurgical, cement, mining, pharmaceutical, detergent and other particulate processing applications. However, these complex processes are difficult to model and operate since the particles can have a wide range of properties, and there is currently no way to predict the optimal operating conditions for a given material.
Steady-state heat transfer by conduction forms the basis for understanding other steady-state and unsteady-state heat transfer in a rotary drum – conduction, convection and radiation. Statistical analysis is carried out to determine the effects of these process parameters and find optimal operating conditions, which will thereby improve the heat transfer efficiency in rotary drums. A stainless-steel drum with a diameter of 6 inches and a length of 3 inches was modeled in EDEM with silica beads of sizes 2 mm, 3 mm and 4 mm at fill levels of 10%, 17.5% and 25%, and at rotation rates of 2 rpm, 5 rpm and 10 rpm. It was found that the heating uniformity increased with decreasing particle size, decreasing fill level and increasing rotation rate. This research is the first step towards studying the other heat transfer modes and various other process parameters. Better understanding of the various heat transfer modes, when used in combination for heating the particles, will be beneficial in improving the operating efficiency, reducing material costs and leading to significant energy conservation on a global scale.
Steady-state heat transfer by conduction forms the basis for understanding other steady-state and unsteady-state heat transfer in a rotary drum – conduction, convection and radiation. Statistical analysis is carried out to determine the effects of these process parameters and find optimal operating conditions, which will thereby improve the heat transfer efficiency in rotary drums. A stainless-steel drum with a diameter of 6 inches and a length of 3 inches was modeled in EDEM with silica beads of sizes 2 mm, 3 mm and 4 mm at fill levels of 10%, 17.5% and 25%, and at rotation rates of 2 rpm, 5 rpm and 10 rpm. It was found that the heating uniformity increased with decreasing particle size, decreasing fill level and increasing rotation rate. This research is the first step towards studying the other heat transfer modes and various other process parameters. Better understanding of the various heat transfer modes, when used in combination for heating the particles, will be beneficial in improving the operating efficiency, reducing material costs and leading to significant energy conservation on a global scale.
ContributorsBheda, Bhaumik (Author) / Emady, Heather (Thesis advisor) / Muhich, Christopher (Committee member) / Nielsen, David (Committee member) / Arizona State University (Publisher)
Created2020