固定式太阳能喷灌系统喷洒水滴动能分布的研究

【目的】提高太阳能喷灌系统水力性能的稳定性和能量转换效率。【方法】采用激光雨滴谱仪测量技术,对225.7~1145 W/m²之间不同光照强度下的固定式太阳能喷灌系统水力特性参数进行试验研究,分析了单个水滴动能、单位体积水滴动能及动能强度等参数的分布规律,并提出了系统能量转换效率的测量及计算方法。【结果】光照强度对单个水滴动能影响主要集中在距离较近处的直径1 mm以下的小水滴;单位体积水滴动能随光照强度的增大先增大后减小并趋于稳定,其径向分布与建立的四次多项式模型拟合较好;动能强度随径向距离的增大而增大,在射程末端迅速减为0,光照强度为300.8~1018.8 W/m²时波动幅度较小;太阳能喷灌系统能量转换效率在24.59%~37.21%之间波动,光照强度为225.7~416 W/m²时,系统能量强度转换效率较高,稳定在36%左右。【结论】在光照强度为300.8~416W/m²时,动能强度波动幅度最小,能量分布更均匀,能量转换效率更高。

Kinetic Energy Distribution of Water Droplets in Fixed Solar Sprinkler Irrigation System

【Background】Solar sprinkler irrigation system is energy-efficient and can reduce operation costs,but it is susceptible to weather and timing of irrigation as insufficient energy supply may occur when demand for power peaks during the irrigation.This could result in low energy conversion efficiency and destabilize hydraulic performance of the system.Light radiation,as an important parameter in designing solar irrigation systems,varies spatiotemporally and could affect the amount of solar energy absorbed by the solar panel and result in unstable electricity supply and changes in water pressure in the system.Currently,there is a lack of protocol for optimizing configuration of the operating parameters of the solar sprinkler irrigation systems.【Objective】Considering that existing solar sprinkler irrigation systems are prone to unstable water pressure,uneven energy distribution and low conversion efficiency,this paper aims to elucidate how light intensity affects the spray performance of the sprinkler irrigation system.【Method】The hydraulic performance parameters of a solar sprinkler irrigation system under light intensities between 225.7 and 1145 W/m² were measured using laser raindrop spectrometer technology,from which we calculated the kinetic energy distribution of the water droplets,kinetic energy per unit volume of water,and the kinetic energy intensity.We also proposed a method to calculate the energy conversion efficiency of the system.【Result】The light intensity mainly affected the kinetic energy of small water droplets with diameter less than 1 mm in the proximity of the sprinkler.As the light intensity increased,the kinetic energy per unit volume increased first and then declined asymptotically in a trend which can be fit by a fourth-degree polynomial function.With the increase in the radial distance from the sprinkler,the kinetic energy intensity increased first and then gradually reduced to 0 at the far end.With the light intensity varying between 300.8 and 1018.8 W/m²,the kinetic energy intensity only showed a small fluctuation and the energy conversion efficiency of the system varied between 24.59%to 37.21%.When the light intensity was in 225.7~416 W/m²,the conversion efficiency of the energy intensity peaked approximately at 36%.【Conclusion】When the light intensity was within 300.8~416 W/m²,the kinetic energy showed the smallest fluctuation,the energy distribution was most uniform,and the energy conversion efficiency maximized.Our results provide a baseline guidance for improving spray performance and energy conversion rate of solar sprinkler irrigation system,and helping optimize configuration of its operating parameters.