A numerical study on the collection efficiency of devices for atmospheric dust deposition

Abstract

Atmospheric dust collection devices are widely used in atmospheric and environmental research to monitor particle deposition. Widely used collection devices include American Society of Testing Materials (ASTM) collectors, Simplified United States Geological Survey (SUSGS) collectors, and inverted Frisbee-type collectors. However, few studies have investigated the collection efficiency of these devices and explored the reasons for the differences in their collection efficiency. In this study, we simulated the collected dust sedimentation of the three devices at several wind speeds using the Eulerian-Lagrangian two-phase flow program. And we compared the results with the amount of dust deposition on the ground surface without a collector. The results show that all three dust collection devices had high collection efficiencies when the airflow velocity was less than 0.75 m/s. However, the collection efficiencies of the three collectors decreased sharply as the wind speed increased, and the collection efficiency decreased with increasing collector aspect ratio (ratio of internal depth to collector inner diameter). The Frisbee-type collection device exhibited the best collection performance. However, the collection efficiency of the three devices with the deflector ring can maintain a high collection efficiency even at high wind speeds. This effect was attributed to the deflector ring effectively weakening the upward wind field on the windward side of the collector opening. Furthermore, particles were drawn by the deflector rings closer to the collector’s opening, facilitating their entry into the collector interior. The larger the area of the horizontal and circular surfaces of the deflector ring, the higher the collection efficiency. Consequently, modifying the deflector ring’s shape represents a promising approach for optimizing collection efficiency.