Tarlei Arriel Botrel

Local head loss for uncoaxial drippers inserted in polyethylene pipes

In this paper, the results of an experimental investigation on local head losses from uncoaxial in-line emitters inserted into the pipe line are reported. Local losses corresponding to four different pipe-emitter combinations, with ten replications, were measured for a range of discharge values. For each discharge, the amount of local losses was calculated as the difference between the total measured head losses and the corresponding friction losses evaluated by the Darcy-Weisbach equation. Mathematical approaches were tested to calculate hfe based on the kinetic head coefficient (K) and constant equivalent length (Le). For the drip-line models examined, the amount of local losses, expressed as a percentage of the total losses, was found to grow with an increase in the obstruction degree. The percentage increased to 24.5% and 50.8%, respectively, for Ag/At = 0.221 and 0.429. The results of this experimental investigation indicated the practical validity of using a constant equivalent length (Le) to estimate the local head losses in a drip lateral line. The percentage variation between total head loss calculated by a step-by-step procedure and the Le approximation method was 5.5% for non-compensating pressure emitters and less than 1.7% for the pressure compensating emitters.

Dióxido de carbono aplicado via água de irrigação na cultura da alface

ABSTRACT Carbon dioxide water for lettuce irrigation.The experiment was carried out in Piracicaba, Brazil, in order toevaluate the effects of carbon dioxide, applied with the irrigationwater, on the productivity and quality of the lettuce cultivated inplastic greenhouse. The treatments were designed in two plasticgreenhouses, one was enriched with CO 2 and the other without CO 2 ,where lettuce variety Ver onica was cultivated. The plastic greenhousehad eight plots with 1.2 x 6.0 m and spaced by 0.8 m. The crop wasirrigated with “Rain Tape ” drip with outflow of 1.15 L/h at operatingpressure of 60 kPa. The irrigation was scheduled on a daily basis inorder to apply 50 liters/m 2 /day of CO 2 daily. The seedlings wereproduced in plastic greenhouse by using isopor tray with vermiculiteas substratum. They were transplanted 30 days after sowing date inbeds of 1.2 m width and 6.0 m length, with 0.30 m spaced betweenplants and 0,30 m between lines. After the application of CO 2 (10/02/97 – 11/02/97) plants were harvested. Enrichment of irrigationwater with CO

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.

Modelagem para o dimensionamento de um sistema de microirrigação utilizando microtubos ramificados

This study was carried out with the aim to develop a mathematical model and to evaluate the hydraulic behavior of branched microtubes, based on the relationship between discharge and microtube length for a specific inlet pressure, operating under laminar flow conditions. Two mathematical models were studied in which one considered the local head losses in irrigation system design and the another did not consider. The experiment for model validation was carried out at the Laboratory of Hydraulics, School of Agriculture Luiz de Queiroz (ESALQ/USP), Piracicaba-SP, where emitter discharges was verified under the pressures of 14.7; 18.6; 39.2 and 58.9 kPa. The irrigation system configuration consisted of a lateral line with nominal diameter (DN) of 10.0 mm, in which are inserted microtube connectors with 0.8 mm DN. These connectors are connected to a derivation tube segment, where six emitter microtubes with 0.7 mm DN were attached. It was verified that the model which considered the local head losses showed better accuracy than other mathematical models, as this model showed a good Willmott index and a low mean quadratic error.

Avaliação do desempenho hidráulico da bomba injetora Indek, para fertigação

In order to obtain good yields of crops, the supply of water and nutrients is essential to plants. A practice that makes the simultaneous application of water and nutrients or agricultural chemicals is called quimigation and its rational use, depends on complete knowledge of the hydraulic performance of the injection system. This study intended to evaluate the hydraulic performance of a injector pump of fertilizers (Indek) with the development and the calibration of a mathematical model to relate the operational conditions (tuning of the course of the pumpx92s pistols, injection and suction pressure) with injection of fertilizers in irrigation systems. Through trials in the laboratory, simulating field conditions, the values of final flow injected were obtained and a mathematical model was elaborated, which estimated the flow of the solution injected satisfactorily at various points of injecting system. The proposed model had better performance for the piston regulations of 20, 30 and 40 mm. For the regulation of 10 mm, good correlation was not obtained among the estimated and observed values of injection flow.

Evaluation of a pulverization system, with emitters working in intermittent mode, on a Notliada central pivot

The aim of this study was to evaluate the difference between estimated and observed emitter flow rates presented by the Notliada pulverization system. The research was undertaken in the Hydraulic Laboratory/Rural Engineering Department at Luiz de Queiroz College of Agriculture, University of Sao Paulo, Brazil. The proposed models showed excellent precision and accuracy indexes. It was determine that emitters of diameter 1.212 (black), 1.016 (red) and 1.020 mm (orange); the solenoid valve must stay turned on for a minimum time of 1.0 s. For the blue emitter of 0.621 mm diameter, this time was 1.4 s. The solenoid valve can be kept turned off for any time between 3 and 9 s. The black and orange emitters had unacceptable uniformity application indexes for turn on times less than 0.7 s. The blue and red emitters had excellent indexes for any tested turn on times. All emitters had excellent uniformity indexes for all tested turn off times used on the solenoid valve.

Coletor automático para ensaio de aspersores em laboratório (1) – desenvolvimento do modelo

The development of a collector for precipitation of the sprinklers in laboratory was studied for implantation at the Laboratory of Testing in Equipments of Irrigation - LEEI. They were studied the best format for the collection of the precipitation, taking into account the factors collected volume, used material and adaptation the automation using sensor of pressure as more economical form of use. It is ended that the collectors possess full capacity of they be used for the testing and tests should be accomplished to confirm the studies.