考虑肥料溶解的压差施肥罐出口肥液浓度计算方法  

Calculation method of fertilizer concentration at outlet based on differential pressure tank considering fertilizer dissolution

作　　者：胡昕宇 严海军[1,2] 陈鑫[1,2] Hu Xinyu;Yan Haijun;Chen Xin(College of Water Resources and Civil Engineering,China Agricultural University,Beijing 100083,China;Beijing Engineering Research Center of Safety and Energy Saving Technology for Water Supply Network System,China Agricultural University,Beijing 100083,China)

机构地区：[1]中国农业大学水利与土木工程学院,北京100083 [2]中国农业大学北京市供水管网系统安全与节能工程技术研究中心,北京100083

出　　处：《农业工程学报》2020年第24期99-106,共8页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家重点研发计划项目(2017YFD0201502);国家自然科学基金资助项目(51836010、41961144014)。

摘　　要：压差施肥罐在中国的水肥一体化中得到了十分广泛的应用。该研究基于含源项的肥料输移扩散连续方程推导了考虑肥料溶解的压差施肥罐出口肥液浓度变化的理论公式,并通过参数描述肥料溶解过程对压差施肥罐出口肥液浓度变化的影响。通过与试验数据对比,理论公式计算的无量纲出口肥液浓度平均绝对偏差、均方差、几何平均偏差、几何方差和两倍偏差之间的预测分数的平均值分别为0.04、0.06、0.89、1.19和88.26%,验证了理论公式对出口肥液浓度计算的准确性。当参数取特定值时,理论公式可以转化为目前广泛应用的无量纲出口肥液浓度压差施肥罐出口肥液浓度的负指数公式。在此基础上,当罐内肥液浓度持续饱和且有充足的肥料可供长期溶解施肥时,考虑肥料溶解过程的均匀施肥方法被进一步探讨。该研究提出的考虑肥料溶解的压差施肥罐出口肥液浓度的计算方法可以实现压差施肥罐出口肥液浓度的准确预测,为考虑肥料溶解的均匀施肥提供可行方案。Differential pressure tank is widely used in the fertigation technology in China because of its low cost,simple and convenient.In this study,a theoretical formula was derived for the fertilizer concentration at outlet based on differential pressure tank considering fertilizer dissolution.The continuity equation for fertilizer transportation and diffusion with source term was used to obtain the differential equation for the fertilizer concentration at outlet.The influence of fertilizer dissolution on the fertilizer concentration at outlet was described by parameters considering the actual process of fertilizer dissolution,and the theoretical formula was obtained for the fertilizer concentration at outlet.In the theoretical formula,one parameter represented the initial dissolution rate of fertilizer in the tank,and the other parameter described the decreasing speed of fertilizer dissolution rate in the tank.When the parameters in the theoretical formula took a specific value,the theoretical formula could be transformed into the classical exponential formula of fertilizer concentration.The variations of source term and fertilizer concentration at outlet with time were further discussed when the parameters took different values.Compared with the experimental data,the theoretical formula considering fertilizer dissolution was suitable for different fertilization experiments and fertilization conditions,and achieved more accurate prediction for fertilizer concentration at outlet than the classical exponential formula and the experimental regression formulas.The classical exponential formula was obviously underestimated for the fertilization experiments with obvious fertilizer dissolution,and the experimental regression formulas were also overestimated or underestimated to some extent for some experimental results.The average values of mean absolute error,root mean square error,geometric mean bias,geometric variance and the fraction of computations within two times the deviation for the theoretical formula were 0.04,0.0

关 键 词：肥料 溶解 水肥一体化 压差施肥罐 出口浓度 理论公式 均匀施肥 

分 类 号：S147.3[农业科学—肥料学]