Hydraulic Design and Evaluation of Variable Speed Pumps on Pressurized Irrigation Systems (Case study: Harkalleh-Laali Irrigation System)

In recent years, energy cost has increased more than other expenses of agriculture sectors. Reconsidering the status of agricultural pumping stations, the features of their energy consumption and applying the new design methods, to increase the efficiency, have valuable roles in controlling energy consumption. In these stations constant-speed pumps are used which could have suitable efficiency in a small range of pressure and discharge changes. If the less pressure or discharge is favored according to irrigation program, the unbalanced relation between motor speed and system curve will, cause high energy losses. This problem, especially in systems like pressurized irrigation that frequently confront the demand changing, imposes extra costs. In this study, Harkalleh-Laali irrigation system, with introducing a method as well as analyzing a practical example, the effects of variable-speed pumps displacement were evaluated in comparison with constantspeed pumps in viewpoints of hydraulics of plan, energy consumption and pump efficiency. Results show that with employing variable-speed pumps in this project, pump efficiency could be increased up to 10% and the reduction of energy consumption per year could reach 49%, related to the current plan.