Simulação da deposição de líquido e avaliação de pontas de pulverização para aplicação de herbicidas.

Abstract

This work had the objective to simulate the liquid deposition and spray nozzles to herbicides application. Therefore, was conducted four experiments to evaluate: 1) the volumetric distribution and droplet spectra by low drift spray nozzles; 2) liquid distribution of air induction and off-center spray nozzle under different conditions; 3) simulation of liquid deposition of a spray boom to herbicide application in tracks in forests areas with different spray nozzles and 4) volumetric distribution of long range eccentric spray nozzles. All tests were performed in the laboratories of the Centre de Mecanització Agraria de la Genaralitat de Catalunya on the campus of the Universitat de Lleida – Spain. In experiment 1 showed the nozzles provided discontinuous profile in 300 and 400 kPa and uniform profile at 200 kPa. Satisfactory CV (under 7%) obtained, when it was used highest pressure and lowest space between nozzles. The droplet size (VMD) was reduced as pressure was increased. Nozzles TTI110015 and AI11015 in all pressures and nozzle AVI11001, in 200 kPa had presented extra coarse droplets and coarse droplets with AVI11001 under 300 and 400 kPa pressures. The nozzles (AI and TTI) had presented more uniformity of droplet size on the highest pressure than AVI, considering the value of span. Nozzles had presented low % 100 µm, out standing the nozzle TTI110015 and AI110015 with smaller value, therefore with smallest drift risk. Was observed in experiment 2, the nozzle AIUB 8502, presented an eccentric distribution of liquid with a discontinuous side and eccentric opposing end, with sharp decrease in the volume of liquid. Increases in the height of the bar and the working pressure extended up the profile distribution. The largest number of uniform configurations was obtained in the height of 50 cm, decreasing in the heights of 40 and 30 cm. The angle and flow rate of the off-center nozzle increased with the increase in pressure, with no differences between discontinuous and total angles between 400 and 500 kPa, and 200 and 300 kPa pressure ranges. Experiment 3 was only observed uniform profile of the bar with the nozzle AIXR space in 100 and 120 cm and the nozzle AIRMIX spaced in 100 cm. All nozzles presented flow rate according to ISO 5682-1 color-coding. In experiment 4 it is observed irregular profile in all conditions to the nozzles XT010 and XP10 with peaks of deposition near to the tip location. The nozzle profile XP20 has slightly more uniform, with greater deposition of liquid in the central belt and abrupt reduction in the extremities. CV% was observed with values ranging from 24.74 to 59.91%. The nozzle XP20 presented seven configurations with CV% below 40% and nozzles XT010 and XP10 with six and two respectively. The increase in pressure and height promoted elongation of the profile and increase the range of spray application, ranging from 1.95 to 5.00 m. The spray nozzles have potential for use in the application of herbicides that do not require good coverage and uniformity of the target as the systemic herbicides applied in post-emergency and herbicides applied in pre-emergency.