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ARS Home » Midwest Area » Wooster, Ohio » Application Technology Research » Research » Publications at this Location » Publication #407510
Research Project: Coordinated Precision Application Technologies for Sustainable Pest Management and Crop Protection

Location: Application Technology Research

Title: Flow rate modulations and droplet size distributions of PWM-controlled hollow-cone nozzles operated at high frequencies and pressures

Author
item CAMPOS, JAVIER - The Ohio State University
item Zhu, Heping
item Jeon, Hongyoung
item ROMAN, CARLA - The Ohio State University
item OZKAN, ERDAL - The Ohio State University
item GIL, EMILIO - Technical University Of Catalonia

Submitted to: ASABE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: 9/20/2023
Publication Date: 10/30/2023
Citation: Campos, J., Zhu, H., Jeon, H., Roman, C., Ozkan, E., Gil, E. 2023. Flow rate modulations and droplet size distributions of PWM-controlled hollow-cone nozzles operated at high frequencies and pressures. ASABE Annual International Meeting. ASABE Paper No. 2300364.

Interpretive Summary:

Technical Abstract: Pulse width modulation (PWM) valves have been used for orchard sprayers equipped with crop recognition sensors to perform precision variable-rate applications in real-time. However, the current use of PWM valves is limited to modulation speeds of 10 Hz and maximum operating pressures of 690 kPa. Based on previous investigations of 12 commercially available PWM valves operated at 1380 kPa and frequencies up to 50Hz, this research selected the two best-performed valves connected to hollow-cone nozzles for further evaluation of their flow rate modulation accuracy and spray droplet size distributions. Tests were conducted with two different orifice sizes of disc-core hollow-cone nozzles controlled by each PWM valve at frequencies ranging from 10 to 40 Hz with 10 Hz intervals and operated at 10, 30, 50, 70, 90, and 100% duty cycles. Flow rates were measured by instantaneously weighing the mass of water discharged from the nozzles for 60 seconds, and droplet sizes were measured with a laser-imaging particle analyzer. Within the flow rate range between 0.09 and 2.84 L min-1 operated at 1380 kPa, the maximum flow modulation error was 32% for all the frequencies and duty cycles tested while droplet size distributions remained relatively consistent. Thus, there would be potential benefits to integrate these high frequency PWM valves into variable-rate orchard sprayers for future improvements of their application accuracy and efficiency.