Droplet size distributions from PWM-controlled hollow-cone nozzles operated at high modulation frequencies and pressures
Sprayers equipped with canopy detection sensors and pulse width modulated (PWM) solenoid valves allow real-time variable rate applications of pesticides to match canopy structures. However, the accuracy of variable-rate applications could be increased by accommodating the modulation speed of the PWM...
| Autores: | , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2025 |
| País: | España |
| Institución: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/426605 |
| Acceso en línea: | https://hdl.handle.net/2117/426605 https://dx.doi.org/10.13031/ja.16094 |
| Access Level: | acceso embargado |
| Palabra clave: | Orchard sprayer Pulse width modulation Variable rate application Pesticide Precision farming Specialty crops. Àrees temàtiques de la UPC::Enginyeria agroalimentària::Enginyeria del medi rural |
| Sumario: | Sprayers equipped with canopy detection sensors and pulse width modulated (PWM) solenoid valves allow real-time variable rate applications of pesticides to match canopy structures. However, the accuracy of variable-rate applications could be increased by accommodating the modulation speed of the PWM valves to the sensor detection speed. Based on previous investigations of 12 commercially available high-frequency PWM valves, two PWM valves with the highest modulation capability were selected for further evaluations. These investigations included the influence of modulation frequency and duty cycle on the droplet size distribution and uniformity of two disc-core hollow-cone nozzles (Teejet D4-DC13 and D5-DC25) manipulated with the two PWM valves operated at pressures of 1034, 1380, and 2068 kPa and modulation frequencies ranging from 10 to 40 Hz and duty cycles (DUCs) between 10% and 100%. Test results showed that droplet size distribution and uniformity remained consistent with varied modulation frequencies. However, DUCs slightly affected droplet size distribution and uniformity, especially when DUCs were below 30%. Therefore, there is a potential to integrate these high-frequency PWM valves, properly operated at DUCs in the range between 30% and 100%, into orchard sprayers to further increase the variable-rate application efficiency while maintaining stable droplet size distributions. |
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