Study on discharge dynamics and droplet characteristics of various nozzle types for pesticide application

This research is aimed at reducing the environmental impact and increasing the efficiency of pesticide application by examining the effects of nozzle type and operating pressure on spray characteristics and discharge rate. Prevalent challenges of applying pesticides had been the subject of prior studies, but the relationships between nozzle types [flat fan, hollow cone, and flower (8-hole)] and operating pressures (2, 3 and 4 kg cm^-2) were not widely recognized for greenhouses. This research gap necessitated an experimental approach, measuring spray deposition and discharge rate across three nozzles using a Malvern Spraytec droplet analyzer and spray patternator. Specific surface area (SSA), volume mean diameter [D(4,3)], Sauter mean diameter [D(3,2)], droplet size distribution (Dv₁₀, Dv₅₀, and Dv₉₀), span were characterized and measured. Data were analyzed using analysis of variance (ANOVA) and Tukey's Honest Significant Difference (HSD) tests to determine significant difference between factors for nozzle selection. The results showed that increasing working pressure of flat fan nozzle from 2 to 4 kg cm^-2 led to smaller droplets sizes, with Dv₁₀, Dv₅₀ and Dv₉₀ decreasing from 85.61 to 66.41 μm, 165.33 to 142.80 μm, and 424.83 to 376.16 μm, respectively. Increase in SSA correspondingly from 0.387 to 0.524 m² cc^-1, indicates more surface area available per unit volume of pesticides. It was found that with increase in discharge rate from 1045.69 to 1360.01 mL min^-1, there was a significant increase in pesticide volume delivered. These findings provide important information for enhancing pesticide application procedures by highlighting the significance of carefully choosing operating pressures and nozzle types to establish a balance between spray efficacy and environmental considerations.