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dc.contributor.advisorWaller, Peter M.en_US
dc.contributor.authorMarouelli, Waldir Aparecido, 1958-
dc.creatorMarouelli, Waldir Aparecido, 1958-en_US
dc.date.accessioned2013-04-18T09:38:17Z
dc.date.available2013-04-18T09:38:17Z
dc.date.issued1996en_US
dc.identifier.urihttp://hdl.handle.net/10150/282265
dc.description.abstractFor chemigation of nonsoluble pesticides, small oil-pesticides droplets (dmax tend to wash-off from foliage while large droplets tend to stick. Large droplets (dmax are buoyant, tend to rise in the irrigation pipeline and exit at the beginning of the pipeline; thus, uniformity and efficacy are poor. For this research, a new chemigation system was proposed. The system removes water from the irrigation pipeline, injects the oil-pesticide into the water stream, increases dispersion velocity in successively smaller tubing diameters, and finally injects the dispersion back into the irrigation pipeline. The higher velocity flow with high turbulent shear forces breaks the oil-pesticide into desired size droplets. Droplet break-up research was reviewed, and a model developed to predict maximum droplet size and size distribution. A maximum relative error of 40% was observed when dmax predicted by the model was compared against literature data. Equations to predict friction factor in helically coiled pipes and effective viscosity of oil-in-water dispersions were evaluated. The friction factor predicted by the Ito equation was in good agreement with the experimental data. Effective viscosity of soybean oil- and kerosene-in-water dispersions was predicted satisfactorily by the Richardson equation with k₄ = 2.5. Finally, center pivot field experiments were conducted using the new and conventional chemigation systems. For the conventional system, the soybean oil uniformity coefficient along the lateral was 61%, and oil applied over the last tenth of irrigated area was 9% of the initial concentration. For the new system, the uniformity coefficient was 73% and 98% for dmax of 875 mum and 98 mum, respectively; oil applied over the last tenth of the area was 27% and 90% of the initial concentration. Field data were compared with those predicted from a pipeline transport model for nonsoluble pesticides. Agreement between the model and the field data was excellent for both experiments using the new chemigation system. Based on the field results and simulation analyses, droplets < 150 μm should be desirable to keep the discharge uniformity coefficient over 97%, for 0.92 ≤ ρ(d)/ρ(c) ≤ 1.04.
dc.language.isoen_USen_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.subjectAgriculture, Plant Pathology.en_US
dc.subjectEngineering, Agricultural.en_US
dc.subjectEngineering, Chemical.en_US
dc.titleImproving chemigation efficacy by controlling droplet size distribution of oil-based pesticidesen_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
thesis.degree.grantorUniversity of Arizonaen_US
thesis.degree.leveldoctoralen_US
dc.identifier.proquest9720681en_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineAgricultural & Biosystems Engineeringen_US
thesis.degree.namePh.D.en_US
dc.description.noteThis item was digitized from a paper original and/or a microfilm copy. If you need higher-resolution images for any content in this item, please contact us at repository@u.library.arizona.edu.
dc.identifier.bibrecord.b34585278en_US
dc.description.admin-noteOriginal file replaced with corrected file October 2023.
refterms.dateFOA2018-09-05T16:15:26Z
html.description.abstractFor chemigation of nonsoluble pesticides, small oil-pesticides droplets (dmax tend to wash-off from foliage while large droplets tend to stick. Large droplets (dmax are buoyant, tend to rise in the irrigation pipeline and exit at the beginning of the pipeline; thus, uniformity and efficacy are poor. For this research, a new chemigation system was proposed. The system removes water from the irrigation pipeline, injects the oil-pesticide into the water stream, increases dispersion velocity in successively smaller tubing diameters, and finally injects the dispersion back into the irrigation pipeline. The higher velocity flow with high turbulent shear forces breaks the oil-pesticide into desired size droplets. Droplet break-up research was reviewed, and a model developed to predict maximum droplet size and size distribution. A maximum relative error of 40% was observed when dmax predicted by the model was compared against literature data. Equations to predict friction factor in helically coiled pipes and effective viscosity of oil-in-water dispersions were evaluated. The friction factor predicted by the Ito equation was in good agreement with the experimental data. Effective viscosity of soybean oil- and kerosene-in-water dispersions was predicted satisfactorily by the Richardson equation with k₄ = 2.5. Finally, center pivot field experiments were conducted using the new and conventional chemigation systems. For the conventional system, the soybean oil uniformity coefficient along the lateral was 61%, and oil applied over the last tenth of irrigated area was 9% of the initial concentration. For the new system, the uniformity coefficient was 73% and 98% for dmax of 875 mum and 98 mum, respectively; oil applied over the last tenth of the area was 27% and 90% of the initial concentration. Field data were compared with those predicted from a pipeline transport model for nonsoluble pesticides. Agreement between the model and the field data was excellent for both experiments using the new chemigation system. Based on the field results and simulation analyses, droplets < 150 μm should be desirable to keep the discharge uniformity coefficient over 97%, for 0.92 ≤ ρ(d)/ρ(c) ≤ 1.04.


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