Avaliação energética de métodos de controle de taxa de aplicação em sistemas de irrigação por aspersão convencional

Abstract

Rio Grande do Sul presents a growing increase in agricultural production, however, the occurrence of phenomena that cause anomalies in the rainfall volume, affects negatively the agricultural development. Faced with this situation, irrigation stands out as a possible solution offered to agriculture. In properties with areas of up to 10 ha, the use of the conventional sprinkler irrigation system is a viable alternative; however, this is one of the main factors responsible for a large part of the consumption of energy in rural areas due to the lack of control in relation to the flow needed to meet the area to be irrigated. This fact is due to the lack of control or technical background regarding the real volume ratio distributed per unit of time. Thus, the objective of this work is to analyze the performance of different flow control methods in sprinkler irrigation systems conventional through simulations of different system configurations. This is justified by the fact that electricity consumption is one of the main factors responsible for increasing production costs in irrigated agriculture and also because of the real possibility of a crisis in the energy sector. In view of this situation, it is possible to mention different methods of flow control in an irrigation system, such as those that do not change the speed of rotation and those that change the speed of rotation of the pump motor in a pumping system. In this way, irrigation systems were designed to serve irrigated areas with sizes ranging from 1, 3, 5, 7 and 10 hectares, comprising different combinations of spacings between sprinklers and irrigation extensions. The spacings of 12 x 12 m were considered; 12 x 18 m; 18 x 18 m; 18 x 24 m and 24 x 24 m, where different application methods were applied: no flow control and fixed irrigation time - M0 (reference method); no flow control and variable irrigation time - M1; control by valve bottleneck and fixed irrigation time - M2; variation of the electric frequency and fixed irrigation time - M3 to carry out the estimation of the energy consumption. However, it was possible to reveal the importance of insertion of the use of flow control method in the projects of conventional sprinkler irrigation system, in order to improve energy efficiency with values ranging from 9.12% to 50.45% in the reduction of consumption power. In addition, it can be concluded that the method that adjusts the flow through the variation of the rotation of the pumping systems was the one that presents the best results.