Optimal Design of Photovoltaic Irrigation System with Different Nozzle Numbers
Authors: Wu Xianfang , Di Meng , Tan Minggao , Liu Houlin 
Published: December 2021

Highlights

When the photovoltaic irrigation system is loaded with different numbers of nozzles, the working pressure of the nozzle will change. This is because the pipeline characteristics have changed with the variation of nozzle number. So the pump operating point changes and its head will also change, which leads to the change of working pressure of nozzle. To solve this problem, by theory analysis based on the test results, it is feasible to make the pump flow rate/head curve flatter. In this case, when the system pipeline characteristics change, the pump head changes little.

This article presents a new optimization method to improve the performance of photovoltaic irrigation systems under variable load. The method just needs to optimize the four pump impeller structure parameters, which can make the pump flow rate/head curve flatter. So the pump head changes a little when the system is loaded with different numbers of nozzles, which can make the working pressure of the nozzle stable and improve the system performance.

Taking the slope of flow-head curve as the optimization objective, and the impeller blade outlet angle ß2, blade outlet width b2, blade number Z, and rear cover diameter D2min as the optimization variables, the performance of the photovoltaic irrigation system is optimized by orthogonal test design optimization scheme. After optimization, when the system is loaded with a different number of nozzles, it can provide relatively similar pressure under different ranges of light intensity.

Abstract. The performance of the photovoltaic irrigation system under variable load were obtained and analyzed through test measurement. The adaptability of the system under variable load could be improved by optimizing the pump impeller structure, and then the irrigation uniformity of the photovoltaic irrigation system under different loads could be improved. Taking the slope of flow-head curve as the optimization objective, and the impeller blade outlet angle ß2, blade outlet width b2, blade number Z, and rear cover diameter D2min as the optimization variables, the performance of the photovoltaic irrigation system is optimized by orthogonal test design optimization scheme and the test verification was carried out. The range method was applied to analyze the simulation results. It can be found that when the geometric parameters of the impeller are D2 = 86 mm, ß2 = 41°, b2 = 4.0 mm, and Z = 9, the slope of the pump flow-head curve is the highest. The system performance after optimization was measured and compared with the original scheme. By comparison, it was drawn that when the system is loaded with different numbers of nozzles, the nozzle pressure can be maintained near the optimal pressure of the nozzle within a wider light intensity. After optimization, when the system is loaded with a different number of nozzles, it can provide relatively similar pressure under different ranges of light intensity. Keywords: Nozzle, Orthogonal test, Optimal design, Photovoltaic irrigation, Pump.