Airborne-Spray-Drift Collection Efficiency of Nylon Screens: Measurement and CFD Analysis

Abstract

Pesticide application is essential for improving crop productivity; however, undesirable pesticide drift must be mitigated because of its adverse impacts on humans, the environment and ecosystems. The collection and accurate quantification of airborne droplets are key elements involved in identifying the spatial and temporal dispersion of off-target spray movement. Various types of passive and active collectors have been deployed to measure airborne spray drift; however, the collection efficiencies of only a few samplers have been verified. This study evaluated the collection efficiency of two airborne-spray-drift collectors using an experimental drift wind tunnel. The airborne spray drifts were quantified by a total organic carbon analyser and validated by comparison to measurements using liquid chromatography with tandem mass spectrometry. Computational fluid dynamics (CFD) simulations were used to explore the effects of droplet size and wind speed on the collection performance. It was found that nylon screens, passive samplers, captured 57.9–88.1% of the airborne spray drift. These results are considered reliable and are comparable to those found in the literature. Additionally, the CFD results demonstrated that the collection efficiency increased with droplet diameter. An increase in wind speed improved the collection efficiency of fine droplets (≤100 μm diameter); however, wind speed had no significant influence on the collection of coarse droplets. These measurements, alongside the aerodynamic approach adopted in this study, can provide a comprehensive understanding of the collection performance of nylon screens.

Keywords

• computational fluid dynamics (CFD)
• drift tunnel
• droplet collection
• nylon screen
• passive collector
• spray drift