Resfriamento adiabático do ar para reduzir perdas por evaporação em pulverização com assistência de ar na barra

• Ano de defesa: 2014
• Autor(a) principal: Sasaki, Robson Shigueaki
• Orientador(a): Teixeira, Mauri Martins
• Banca de defesa: Ferreira, Lino Roberto , Vieira, Rogério Faria , Rodrigues, Gilton Jose
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Engenharia Agrícola
• Departamento: Construções rurais e ambiência; Energia na agricultura; Mecanização agrícola; Processamento de produ
• País: BR
• Palavras-chave em Português: Produtos químicos agrícolas - Aplicação; Pulverização; Resfriamento adiabático; Máquinas agrícolas
• Palavras-chave em Inglês: Agricultural chemicals - Application; Spraying; Adiabatic cooling; Agricultural machinery
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA
• Link de acesso: http://locus.ufv.br/handle/123456789/787

Pesticides application in high temperature and low relative humidity may cause droplet evaporation. Consequently there are product losses to environment, which may cause environmental pollution. Using hydraulic sprayers with air assisted spraying boom the losses may be aggravated, once air flux when faces the sprayed droplets promotes heat and mass transfer from droplet to air. This work aimed to evaluate the effect of air psychometric conditions on the spraying technical parameters; to develop and to evaluate different adiabatic cooling systems with potential use in pesticides application to reduce evaporation loss; and to evaluate the effect of using the adiabatic cooling system on the spraying technical parameters. The entire essay was done from the development of a prototype, which was equipped with an axial fan, a flux homogenizer, temperature and relative humidity probes, hydraulic spray nozzle and gas heating system to warm up the air flux. With the assembled system and the aid of a laser analyzer (model Spraytec, MalvernInstruments Co., Worcestershire, UK) the hydraulic nozzle JSF 11002 was evaluated in relation to the parameters DV0.1, DV0.5, DV0.9, Span, %V<100, 100<%V<200, 200<%V<300, 300<%V<400, 400<%V<500 and 500<%V<600 &#956;m, in four air psychometric conditions (7, 14, 21 and 28 hPa). Afterwards, evaluations for the best adiabatic cooling method to be used for pesticides application were followed. Four evaporative cooling systems were evaluated: 1) low pressure nebulizers; 2) intermittent nebulizing system equipped with low pressure nozzles; 3) cellulose plates and 4) high pressure nebulizers. Having the best adiabatic cooling system, it was evaluated the effect of using this system in relation to spraying technical parameters in four air psychometric conditions (9, 17, 25 and 32 hPa). The different psychometric conditions caused evaporation losses during the sprayings. Using the spray nozzle JSF 11002 for a certain working pressure at each increase of 1 hPa in VPD there was a reduction of the droplet diameter at the order of 0.0759; 0.518 and 1.514 &#956;m for DV0.1; DMV e DV0.9 parameters, respectively. With the increase of VPD during the sprayings occurred a displacement in droplets size class which compounds the spectrum. The increasing of air evaporative potential, increases the volume of droplets belonging to the classes of %V<100; 100<%V<200 and 200<%V<300 &#956;m, and simultaneously reduces the volume of the classes of 300<%V<400; 400<%V<500 and 500<%V<600 &#956;m which compound the spectrum. The air evaporative potential has reached 39% of the total sprayed volume. The best adiabatic cooling system with potential to be used in pesticide application was the high pressure nebulizers. This system proportioned reduction of VPD up to 19.7 hPa and did not present problems in relation to liquid runoff and air speed fall. Adiabatic cooling system during the sprayings reduced evaporation losses.