Exploring the Impact of Diffuser Design on Droplet Dispersion in Indoor Spaces

SUNIL KUMAR, Maria King, Texas A&M University

     Abstract Number: 461
     Working Group: Aerosol Science of Infectious Diseases: Lessons and Open Questions on Models, Transmission and Mitigation

Abstract
Aerosolization of contaminants including respiratory droplets poses a crucial problem for indoor environments of homes, hospitals, vehicles, facilities requiring early decontamination measures to keep the occupants safe. The HVAC systems installed to provide fresh air play a major role in contributing to the spread of contaminants. The number of Air Change Hours required for different indoor environments are standardized by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) for a mandated 6ACH in hospitals. However, the configuration of air distribution in these indoor environments remains at discretion of HVAC engineers and primarily on choice of manufacturer, and owners. This type of diffuser is critical for achieving early decontamination of the indoor environment. This study evaluates the most used diffuser design to understand the development of air flow patterns and their role in dispersing the contaminated sneeze droplets at different ACH. Further analysis of the design shows that the flow vortices are dependent on the interaction of reflected air from different stationary objects including the walls. The droplets trapped in these vortices tend to recirculate along with indoor air and deposit in specific locations or remain aerosolized for a longer time. The probability of risk of spread of infection increases many folds the longer the droplets remain aerosolized. This study offers insight into ventilation design optimization to mitigate pathogen spread.