Hidrociclone para pré-filtragem da água de irrigação

A utilização de água contendo partículas sólidas em suspensão tem sido a causa de sérios problemas em sistemas de irrigação. A escolha do tipo e capacidade do sistema de filtragem é de fundamental importância para evitar aumento nos custos de operação e manutenção do sistema de irrigação. Pré-filtros, como os hidrociclones, caracterizam-se por significativo poder de separação de partículas presentes na água. Apesar de algumas referências feitas aos hidrociclones, não se dispõe no Brasil de resultados do desempenho dos mesmos, quando empregados em pré-filtragem da água utilizada nos sistemas de irrigação. Assim, um experimento compreendeu a construção e a avaliação do desempenho de quatro hidrociclones do tipo Rietema, utilizando-se suspensões de areia fina e de solo argiloso, sob diferentes diferenciais de pressão, e adotando-se como critério de comparação a capacidade de vazão e o poder de separação, medidos pela eficiência total e eficiência total reduzida. O hidrociclone dotado com bocal de alimentação circular apresentou os maiores índices nos critérios de comparação, com suspensão de areia e suspensão de solo.The use of water containing suspended sediments causes serious problems to irrigation systems. Choosing the right filtering system type and capacity is essential to avoid increases in operational and maintenance costs of irrigation resulting from the need for cleaning and frequent component replacing. Pre-filters, such as the hydrocyclone, are important for their significant capability of retaining particles suspended in the water. Data on hydrocyclones performance for pre-filtering of irrigation water can be found in the literature, but research data in Brazil are scarce. Therefore, four Rietema type hydrocyclones (50 mm diameter) were constructed, one with circular-end and the other three presenting rectangular-end feeding tubes. The evaluation of hydrocyclones performance was conducted by using suspensions of fine sand and clay soil particles under varied pressure differentials. The comparison criteria were the discharge and the separation capability, given by total efficiency and reduced total efficiency. The hydrocyclone with circular-end feeding tube presented the highest indexes for the adopted criteria, considering sand and soil suspensions

CONDUTÂNCIA HIDRÁULICA E TEMPO DE RESPOSTA DE TENSIÔMETROS UTILIZADOS EM CULTIVOS FERTIRRIGADOS

The tensiometer has been largely used for proper irrigation scheduling due to its simplicity, low cost and satisfactory precision. Although there is an increasing tendency of using fertirrigation, experimental data relating this practice to the cup hydraulic conductance and response time of the tensiometer are not available. The present study aimed to evaluate the changes on the hydraulic conductance (CH) and on the response time (TR) of ceramic cups after the cups were submitted to the following treatments: (a) immersion for 30 days in fertilizer solution with increasing concentrations; (b) use to monitor water availability to pepper grown in sandy and clay soils under irrigation and fertirrigation. CH increased and TR decreased accordingly to the increasing fertilizer solution concentration after immersion; CH decreased after the field trial with pepper; fertilizers added to the irrigation water did not influence CH and TR; soil texture did not affect CH and TR at 60 kPa tension.O tensiômetro tem sido largamente utilizado como ferramenta no manejo da irrigação, tendo em vista sua praticidade, baixo custo e satisfatória precisão na determinação da tensão de água do solo. Com a tendência crescente do uso da fertirrigação, não se dispõe de dados a respeito das possíveis interações desta prática na condutância hidráulica e no tempo de resposta das cápsulas de cerâmica utilizadas nos tensiômetros. O trabalho procurou avaliar possíveis alterações na condutância hidráulica (CH) e no tempo de resposta (TR) de cápsulas de cerâmica após as mesmas terem sido submetidas aos seguintes tratamentos: (a) imersão pelo período de 30 dias em solução fertilizante com concentrações iônicas crescentes; (b) utilização no monitoramento da disponibilidade hídrica da cultura do pimentão cultivado em solo arenoso e argiloso, sob irrigação e fertirrigação. Verificou-se aumento da condutância hidráulica e redução dos tempos de resposta com o aumento da concentração da solução a que as cápsulas foram imersas; redução da condutância hidráulica após o período de cultivo do pimentão; não influência do acréscimo de fertilizantes à água de irrigação nas características avaliadas; não influência da textura do solo na condutância hidráulica e no tempo de resposta a tensão de 60 kPa

Hydrocyclone for pre-filtering of irrigation water

The use of water containing suspended sediments causes serious problems to irrigation systems. Choosing the right filtering system type and capacity is essential to avoid increases in operational and maintenance costs of irrigation resulting from the need for cleaning and frequent component replacing. Pre-filters, such as the hydrocyclone, are important for their significant capability of retaining particles suspended in the water. Data on hydrocyclones performance for pre-filtering of irrigation water can be found in the literature, but research data in Brazil are scarce. Therefore, four Rietema type hydrocyclones (50 mm diameter) were constructed, one with circular-end and the other three presenting rectangular-end feeding tubes. The evaluation of hydrocyclones performance was conducted by using suspensions of fine sand and clay soil particles under varied pressure differentials. The comparison criteria were the discharge and the separation capability, given by total efficiency and reduced total efficiency. The hydrocyclone with circular-end feeding tube presented the highest indexes for the adopted criteria, considering sand and soil suspensions

Corn performance with late sowing in Planalto Catarinense, Brazil, simulated with CERES-maize model

This work had the objective to investigate the delay effects in the sowing date on corn establishment, cycle duration and yield through the computer simulations using CERES-Maize model, in order to help agrarian producers from the Mountainous Area of Santa Catarina, Brazil to take better decisions on it. The computer simulations showed that: 1)the risks on corn establishment increased due to the delay of sowing during the studied years; 2) in some years, its cycles were drastically affected for the lower temperatures; 3) the cycle durations were longer when confronted with the low temperatures; 4) corn income decreased when the cycles were confronted with the low temperatures, water deficiency and low solar radiation; 5) potential incomes averaged 4944 kg ha-1, and under the natural rain conditions averaged 2490 kg ha-1, during all the months analyzed from October to March; 6) besides January, the exploration of this cultivar was not viable because of the high risk of the crop frustration associated to the same ones, due to the thermal conditions (low temperatures and frost)

Wind power characterization in the Lages city - SC, Brazil

The main objective of this work was to determinate the nominal wind and the wind power, based on mathematical adjustments in the Lages city, SC-Brazil. The study used data comprising the period between 1976 and 2006. The wind average velocity was osted by Lages Meteorological Station located at 27º49'S, 50º12' W, and 937 meters of altitude. For the estimated wind temporal distribution, a methodology based on wind velocity curves was used. The nominal velocity that made wind power maximum in Lages was 10.33 km h-1 77 days long. This velocity provides an average wind power 16.6 W m-2 annually. The results showed that wind power cow be characterized as a simple alternative to be used in agriculture.Nos últimos anos, aumentaram os estudos sobre energias renováveis como uma alternativa às fontes convencionais. O objetivo do trabalho foi determinar, a partir de ajustes matemáticos, a velocidade nominal do vento e o potencial eólico para o município de Lages-SC baseado em dados de velocidade média diária entre os anos de 1976 a 2006. Os dados de velocidade média do vento foram coletados a 10 m de altura, na Estação Meteorológica de Lages, SC, situada a 27º 49' de latitude Sul e a 50º 12' de longitude Oeste, a 937 metros de altitude. Para a estimativa da distribuição temporal do vento, utilizou-se metodologia baseada em curvas de velocidade do vento. A velocidade nominal que torna máximo o potencial eólico em Lages é de 10,33 km h-1 com duração de 77 dias fornecendo uma potência média anual de 16,6 W m-2, viabilizando seu uso na agricultura, caracterizando uma alternativa simples

Generation of intensity duration frequency curves and intensity temporal variability pattern of intense rainfall for Lages/SC

The objective of this work was to analyze the frequency distribution and intensity temporal variability of intense rainfall for Lages/SC from diary pluviograph data. Data on annual series of maximum rainfalls from rain gauges of the CAV-UDESC Weather Station in Lages/SC were used from 2000 to 2009. Gumbel statistic distribution was applied in order to obtain the rainfall height and intensity in the following return periods: 2, 5, 10, 15 and 20 years. Results showed intensity-duration-frequency curves (I-D-F) for those return periods, as well as I-D-F equations: i=2050.Tr0,20.(t+30)-0,89, where i was the intensity, Tr was the rainfall return periods and t was the rainfall duration. For the intensity of temporal variability pattern along of the rainfall duration time, the convective, or advanced pattern was the predominant, with larger precipitate rainfalls in the first half of the duration. The same pattern presented larger occurrences in the spring and summer stations