A. James Clark School of Engineering

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The collections in this community comprise faculty research works, as well as graduate theses and dissertations.

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    The Influence of Plastic Barriers on Aerosol Infection Risk during Airport Security Checks
    (MDPI, 2022-09-08) Zhu, Shengwei; Lin, Tong; Spengler, John D.; Cedeño Laurent, Jose Guillermo; Srebric, Jelena
    Plastic barriers physically separate queuing passengers in airport security check areas as a measure against aerosol transmission. However, this may create “canyons” that interfere with the existing ventilation design: potentially inhibiting airflow, concentrating exhaled viruses, and exacerbating aerosol transmission risk. Accordingly, this study investigated the transmission implications of installing plastic barriers in a security check area with computational fluid dynamics (CFD). Two air distribution schemes were modeled: one with linear air supply diffusers aligned vertically to (Case 1) and another with diffusers parallel with (Case 2) the orientation of partitions. The drift-flux model was used to calculate the spread of viral bioaerosols with 5 µm in diameter; then the Wells–Riley equation was applied to assess aerosol transmission risk for SARS-CoV-2. According to simulation results, in Case 1, installing plastic barriers resulted in relatively small changes in volume with a high infection risk of 1% or greater in the breathing zone within the first 25 min. However, in Case 2, using plastic barriers resulted in the continuous increase in this volume within the first 25 min while this volume was near zero if without plastic barriers. In conclusion, installing plastic barriers needs careful consideration because they do not reduce the risk of airborne SARS-CoV-2 transmission and might even exacerbate it without localized ventilation and air cleaning.
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    VENTILATION IMPACT ON AIRBORNE TRANSMISSION OF RESPIRATORY ILLNESS IN STUDENT DORMITORIES
    (2018) Jenkins, Sara T; Srebric, Jelena; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This work presents a study of the effect of ventilation rates on the bioaerosols that cause upper respiratory illness. A network of 147 sensors was placed in a pair of dormitories on a college campus to measure carbon dioxide concentrations over two semesters. The concentration results served as input into multi-zone ventilation models of the two buildings, which had different heating, ventilation, and air conditioning (HVAC) systems. The dormitory with a central mechanical ventilation system had, as expected, a higher turnover of fresh air compared to the other, which relied on exhaust fans and infiltration. This well-ventilated building also contained far fewer occupants with recorded upper respiratory illness incidence in comparison to the poorly ventilated building. The central ventilation system increased dorm room ventilation rates by 500%, while decreasing respiratory illness incidence by over 85%. Comparative studies have shown similar findings with increased ventilation reducing incidence of upper respiratory illness by an order of magnitude.