Multi-objective optimization of low-cost high-pressure glasshouse atomization: High-speed imaging mechanism for...

Chemical pesticides remain the primary strategy for controlling greenhouse whiteflies (Bemisia tabaci), yet traditional application systems are plagued by uneven droplet distribution, severe pesticide drift, and inadequate control efficacy - all of which contradict cleaner production objectives. To address these challenges, this study proposed a multi-objective optimization framework for low-cost high-pressure glasshouse atomization, integrating a high-speed imaging mechanism to achieve targeted droplet uniformity, environmental sustainability, and efficient whitefly control. A self-developed low-cost high-precision atomization system was constructed, featuring polypropylene Venturi-swirl integrated atomizing nozzle (PP-VSIN). High-speed imaging was employed to capture the transient behaviors (spreading, trajectory, and deposition) of water and pesticide droplets on tomato crops, enabling quantitative analysis of droplet size distribution (DSD), coefficient of variation (CV), and target leaf contact characteristics under varying conditions: spray pressure (2, 5, and 8 MPa), nozzle-tomato horizontal distance (0.5, 0.75, and 1 m), and spray angle (90°, 120°, and 180°). Results demonstrated that the mixed pesticide solution reduced the contact angles on tomato leaves, water-sensitive paper, and polyvinyl chloride (PVC) cards, effectively enhancing the spreading and adhesion capabilities of droplets on tomato surfaces. Droplet size spectrum analysis revealed that the average droplet size decreased with increasing spray pressure, and particularly when pressure increased from 5 to 8 MPa, droplet deposition and penetration were significantly improved. Tomato canopy deposition followed the order of upper > middle > lower (6.300, 6.226, and 6.062 μL cm^-2), with minimal overall differences, while droplet coverage was the lowest on the upper and lower leaves of the canopy (21.02% and 21.15%, respectively). Multi-objective optimization confirmed the optimal parameters: 0.75 m single-side nozzle spacing, 180° spray angle, 8 MPa spray pressure, and 225 L hm^-1 application rate. This parameter combination exhibited excellent atomization performance and whitefly control efficacy, with the control efficacy of six treatments stabilizing at 79.68-89.01% on the seventh day and remaining above 79% thereafter. Compared with traditional application systems, pesticide usage was reduced by 33.33%. This system achieves a balance among performance, cost, and environmental sustainability, improves targeted pest control, and promotes environmental sustainability. It bridges the gap between mechanistic understanding and practical application, providing a scalable and sustainable clean production solution for pest management in small-to-medium glasshouses. © 2026 Society of Chemical Industry.