Caracterização Hidráulica de Tubos Porosos de Pneus Reciclados Usados em Irrigação Subsuperficial

Abstract

Porous pipes made of recycled tires have been manufactured for deployment in subsurface irrigation laterals. These pipes are considered an environment-friendly product because it helps to reduce environmental problems brought about by the disposal of waste rubber. On the other hand, any product applied for irrigation must present qualities required to support its technical feasibility for in-field uses. The objective of the research was to study a rubber-made porous pipe in laboratory conditions to determine the relation between head loss and flow rate, pressure-flow rate curve, and uniformity of flow rate. The work was developed in the Irrigation Laboratory, Department of Biosystems Engineering ESALQ / USP, during the first half of 2011. Five samples of pipes were assessed for determining head loss. These tests involved porous pipes operating normally and waterproofed. The pressure-flow rate relation and the uniformity of flow rate were determined evaluating 8 samples under 7 operating pressures (29.4, 39.2, 49.1, 58.9, 68.7. 78.5 and 88.3 kPa). A mathematical model was developed for representing the curve flow rate-head loss of the porous tube, based on the Darcy-Weisbach equation and Hooke's law to three dimensions. The equipment used in the tests were magnetic flowmeter, mercury manometer, digital pressure gauge and balance. The coefficient of variation of flow was around 5%, which represents a satisfactory result. The power-law function did not fit to the experimental data of pressure-flow rate, but the developed model had a good fit. The head loss coefficient and the friction factor due to outflow of emitters presented values disagreeing from