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| Relationship between solar energy and sprinkler hydraulic performance of solar sprinkler irrigation system |
| LIU Junping*, XU Jien, LI Tao, ZAMAN Muhammad |
| Research Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China; |
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Abstract Facing the shortage of energy and the limitation of water resources, the development of agricultural irrigation has been constrained, especially in some remote areas where the maximum electricity cannot be fully guaranteed. The solar sprinkler irrigation system can save energy and water. It can greatly improve the efficiency of farmland irrigation, reduce labor costs, and solve the problem of irrigation power in the areas where electricity power is in shortage. However, the hydraulic performance of solar sprinkler irrigation system, which are put into use currently, is poor, limiting the development of solar sprinkler irrigation system. In order to solve the problem that the hydraulic performance can not be effectively predicted in the application of solar sprinkler irrigation system, summer experiments on the hydraulic performance of the solar sprinkler irrigation system under typical weather were carried out, taking the solar energy intensity as the influencing factor, and taking the pump outlet flow rate, pump outlet pressure, sprinkler wet radius, water distribution and irrigation uniformity coefficient of the system as the evaluation index, to find which is the better data of the solar energy intensity. The change rule of spraying hydraulic performance under solar energy intensity was obtained, and the solar energy intensity data needed under the optimum working condition of the system was obtained. The experimental results show that system flow rate and pump outlet pressure increase with the increase of solar energy intensity, and the variation of pump flow rate and pressure with solar energy intensity basically conforms to the exponential distribution law. When the solar energy intensity is more than 800.0 W/m2, the system flow rate is about 1.82 m3/h, and remain unchanged, pump outlet pressure at the same time is stable at 0.43-0.44 MPa. The sprinkler wet radius generally showed a slight upward trend which between is 8.9 m and 9.7 m with the increase of solar energy intensity. When the solar energy intensity is more than 900.0 W/m2, the sprinkler wet radius fluctuates to a certain extent and keeps at about 9.2 m. When the solar energy intensity is more than 200.0 W/m2, the wet radius tends to be stable. The curve shape of water distribution tends to flatten gradually from triangle with the increase of solar energy intensity. When the average solar energy intensity is about 225.7 W/m2, the curve shape of water distribution tends to be trapezoidal. When the solar energy intensity is more than 900.0 W/m2, the curve shape of water distribution remained basically unchanged. The function relationship between average solar energy intensity and uniformity coefficient was obtained. When the solar energy intensity is more than 900.0 W/m2, the uniformity coefficient CU of sprinkler irrigation system is more than 88%. When the solar energy intensity is between 200.0 W/m2 and 600.0 W/m2, the uniformity coefficient of sprinkler irrigation is between 76% and 82%. The solar sprinkler irrigation system can work normally when the solar energy intensity is above 200.0 W/m2. This study can provide references for realizing the combination of solar energy and agricultural machinery, improving hydraulic perfor-mance of solar sprinkler irrigation system, promoting the popularization and application of solar sprinkler irrigation system in practical projects and solving the problem of irrigation power shortage in the areas with less electricity energy.
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Received: 02 September 2019
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