Impact of human walking on the pollutant removal effectiveness of direction air supply considering environmental disturbances: Dynamic simulation study

Abstract

Direction air supply (DAS) is a computer vision-assisted ventilation mode designed to address the challenge of respiratory protection during human movement. The DAS parameter design is based on ideal, steady-state air distribution results, but it cannot reflect the dynamic protection performance. This work investigates the effect of human walking on the pollutant removal effectiveness of DAS through computational fluid dynamics simulation with the dynamic mesh method. This work formulates an occupant's movement pattern and implements walking and turning motions using the overset mesh method. To verify the feasibility of the dynamic simulation method, a walking experiment was conducted in an experimental chamber equipped with a DAS system. The evolution of concentration isosurfaces, as well as the concentration, velocity, and static pressure at breathing-zone height are revealed. The negative impacts of three common industrial environmental disturbances: localized high-temperature pollutants, ambient airflow, and distance between the DAS nozzle and the breathing zone, on the protective zone and the DAS barrier against pollutants are analyzed. To comprehensively evaluate the effectiveness of DAS, four assessment indexes are determined: inhalation exposure, protection factor, protective zone area, and effective protective ratio. The inconsistency between the protective zone area and the effective protective ratio needs to be noted. This work confirms the effectiveness of DAS within the protective zone and supports its further application in industrial settings.