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Simulations of Aerosol Exposure from a Dusty Table Source

Dolan, Kevin
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1562673613531829

Abstract Details

2019, MS, University of Cincinnati, Engineering and Applied Science: Mechanical Engineering.
Inhalation exposure of fine and ultrafine particles is a large hazard for individuals working around aerosolized particles. As of yet, there is no clear direct relationship between this inhalation exposure and a material property (dustiness) of the powder. Several methods exist for determining the dustiness of powders: drop test, rotating drum, and Venturi aerosolization. Previous experiments have attempted to correlate the dustiness of a powder and the inhalation exposure of a worker performing activities. Given the wide range of other variables (type of activity, positioning, air flows), it is difficult to isolate the exposure relating purely to dustiness. The National Institute for Occupational Safety and Health (NIOSH) is proposing a series of experiments using simplified work and clean-up activities, designed to remove these sources of variation. This will provide a direct link between the dustiness of a powder and the inhalation exposure of a given task. The studies in this thesis aid in the design of the NIOSH experiments. A series of computational fluid dynamics studies have been conducted as a predictive resource for the proposed NIOSH experimental exposure studies with powders. The simulations reported in this thesis focused on air flowing in a rectangular room past a simplified worker and work table. The dimension of the work space and air flow conditions were chosen to mimic the proposed NIOSH experiments in their ventilation lab. Inhalable and respirable samplers were positioned on the worker. Particles were released above the table surface to follow their movement around the room. The position of the simplified worker around a work table was varied, as well as the location of samplers on the worker’s torso. The air flow in the room is significantly perturbed by the presence of the worker and table; a recirculation zone develops downstream of the worker, and vortices are shed downstream of the table legs. The location of the worker has a large effect on the flow patterns in the room and, consequently, on the particle sampling. The particle tracks show how the particles travel through the room with time, and the originating location of each particle that enters the samplers. The results show that the location of the worker relative to the work surface is extremely important, as well as the positioning of the samplers on the worker’s torso for certain configurations. Both of these need to be controlled carefully for reproducible results. In addition, the samplers are sensitive to a certain region of space, and detect particles only from specific areas on the table. This means that the location of the work activity during the experiment needs to be highly controlled for reproducible results. A general theme emerges from the results in this thesis: the particles act as a plume emerging from the table, and the samplers act as a reverse plume (or sink) pulling the particles into the samplers. The industrial hygiene paradigm is that samplers detect an average toxicant concentration of a well-mixed environment. The results in this thesis demonstrate that the NIOSH experimental room is not adequately described as a well-mixed environment. Exposure is the intersection of a toxicant source plume with a detection sink plume, and is spatially-temporally dependent.
Urmila Ghia, Ph.D. (Committee Chair)
Milind Jog, Ph.D. (Committee Member)
Leonid Turkevich, Ph.D. (Committee Member)
188 p.
Mechanical Engineering
Computational Fluid Dynamics; CFD; Occupational Dust Exposure; Particle Tracking; Unsteady Turbulent Flow

Recommended Citations

Citations

  • Dolan, K. (2019). Simulations of Aerosol Exposure from a Dusty Table Source [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1562673613531829

    APA Style (7th edition)

  • Dolan, Kevin. Simulations of Aerosol Exposure from a Dusty Table Source. 2019. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1562673613531829.

    MLA Style (8th edition)

  • Dolan, Kevin. "Simulations of Aerosol Exposure from a Dusty Table Source." Master's thesis, University of Cincinnati, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1562673613531829

    Chicago Manual of Style (17th edition)

ucin1562673613531829
190
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This open access ETD is published by University of Cincinnati and OhioLINK.