Effect of magnetic field on surface tension and droplet size of metolachlor herbicide solution
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摘要:目的
研究磁化作用对除草剂溶液表面张力及除草剂喷雾雾滴粒径的影响规律，探索新型除草剂喷雾雾滴粒径控制方法。
方法设计磁化除草剂溶液表面张力试验和磁化喷雾雾滴粒径试验，记录不同磁场强度和磁化时长2个影响因素下除草剂溶液表面张力和喷雾雾滴粒径，观测数据变化规律；并对数据进行拟合，给出符合数据变化的函数关系式。
结果在磁场强度为50~500 mT、磁化时长为5.0~25.0 min范围内，溶液表面张力和喷雾雾滴粒径均随磁场强度和磁化时长的增加呈现先下降后回升的趋势；当磁场强度为350 mT、磁化时长为15.0 min时，表面张力和雾滴粒径下降幅度最大，表面张力为54.0 mN/m，下降14.96%，喷雾雾滴粒径为108.75 μm，下降11.20%。对表面张力数据进行拟合，洛伦兹拟合函数的决定系数(R2)为0.816 4，调整后R2为0.794 0，均方根误差(Root mean square error，RMSE)为1.105 9；雾滴粒径数据拟合中，多项式拟合函数的R2为0.833 6，调整后R2为0.787 4，RMSE为2.085 7。拟合函数有意义且拟合精度较高。
结论磁化作用并不是磁场强度越大或磁化时长越长磁化效果越好，而是存在最佳磁化处理强度和磁化时长；本研究给出的洛伦兹模型函数可作为除草剂溶液表面张力与磁化作用的函数关系式，三次多项式函数可作为350 mT磁场强度下雾滴粒径调控模型。
Abstract:ObjectiveTo study the effect of magnetization on surface tension of herbicide solution and particle size of herbicide spray droplet, and explore a new control method of particle size of herbicide spray droplet.
MethodThe surface tension experiment of the magnetized herbicide solution and the particle size experiment of the magnetized spray droplet were designed to record the surface tension value of the herbicide solution and the particle size value of the spray droplet under the influence of two factors of different magnetic field intensity and magnetization duration, observe the change rule of the data, and fit the data, and give the functional relationship that conforms to the description of the data change.
ResultWhen the magnetic field intensity was 50−500 mT and magnetization duration was 5.0−25.0 min, both the surface tension of solution and the particle size of spray droplet decreased firstly and then rose with the increase of magnetic field intensity and magnetization duration. When the magnetic field intensity was 350 mT and magnetization duration was 15.0 min, the surface tension and particle size of spray droplet decreased the most. The surface tension value decreased to 54.0 mN/m with a drop rate of 14.96%, and the spray droplet size decreased to 108.75 μm with a drop rate of 11.20%. For surface tension data, the determination coefficient (R2) of Lorentz fitting function was 0.816 4, adjusted R2 was 0.794 0, root mean square error (RMSE) was 1.105 9; And the R2 of polynomial fitting function for spray droplet size data was 0.833 6, adjusted R2 was 0.787 4, RMSE was 2.085 7. The fitting function was meaningful and the fitting precision was high.
ConclusionIt is not that the magnetization effect will be better with the increase of magnetic field intensity or magnetization duration, but that the optimal magnetization intensity and duration exist. The Lorentz model function given in this paper can be used as the function relation between the surface tension of herbicide solution and magnetization, and the cubic polynomial function can be used as the model for controlling the particle size of fog droplets under the magnetic field intensity of 350 mT.
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Keywords:
- Magnetized treatment /
- Metolachlor /
- Surface tension /
- Droplet size /
- Data fitting
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图 4 磁化溶液雾滴粒径测试系统
1：雾化喷头；2：激光粒度仪；3：双轭双调气隙电磁发生系统；4：隔膜泵；5：压力表；6：高斯计；7：程控功率电流源；8：稳压电源；9：水箱
Figure 4. Particle size measurement system for droplets of magnetized solution
1: Atomizing nozzle; 2: Laser particle size analyzer; 3: Dual yoke dual tuned air gap electromagnetic generation system; 4: Diaphragm pump; 5: Pressure gauge; 6: Gauss meter; 7: Programmable power current source; 8: Regulated power supply; 9: Tank
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图 5 磁化除草剂溶液表面张力图
Figure 5. Surface tension distribution diagram of magnetized herbicide solution
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图 6 磁化除草剂溶液表面张力拟合曲面
Figure 6. Surface tension fitting surface of magnetized herbicide solution
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图 7 磁化除草剂溶液喷雾雾滴粒径图
Figure 7. Droplet size distribution diagram of magnetized herbicide solution
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图 8 磁化除草剂溶液雾滴粒径拟合曲面
Figure 8. Fitting surface of fog droplet size of magnetized herbicide solution
表 1 磁化除草剂溶液表面张力试验设计表
Table 1 Test program list of surface tension of magnetized pesticide solution
处理编号 No. of treatment 磁场强度/mT Magnetic field intensity 磁化时间/min Magnetization time 1 0 2 50 5.0、10.0、15.0、17.5、20.0 3 100 5.0、10.0、15.0、20.0、25.0 4 150 5.0、10.0、15.0、20.0、25.0 5 200 5.0、10.0、15.0、17.5、20.0 6 250 5.0、10.0、15.0、17.5、20.0 7 300 5.0、10.0、15.0、17.5、20.0 8 350 5.0、10.0、15.0、17.5、20.0 9 400 5.0、10.0、12.5、15.0 10 450 5.0、10.0、12.5、15.0 11 500 5.0、10.0、12.5、15.0 
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表 2 磁化除草剂溶液表面张力试验结果
Table 2 Results of surface tension test of magnetized herbicide solution
磁场强度/mT Magnetic field intensity 磁化时长/min Magnetization time 表面张力/(mN·m−1) Surface tension 磁场强度/mT Magnetic field intensity 磁化时长/min Magnetization time 表面张力/(mN·m−1) Surface tension 50 5.0 63.2 250 20.0 60.3 50 10.0 62.8 300 5.0 59.5 50 15.0 62.3 300 10.0 57.6 50 17.5 62.7 300 15.0 55.2 50 20.0 63.0 300 17.5 56.3 100 5.0 62.7 300 20.0 57.5 100 10.0 61.9 350 5.0 59.4 100 15.0 61.4 350 10.0 55.6 100 20.0 61.1 350 15.0 54.0 100 25.0 61.3 350 17.5 56.2 150 5.0 62.3 350 20.0 60.5 150 10.0 61.9 400 5.0 62.2 150 15.0 60.8 400 10.0 59.6 150 20.0 60.2 400 12.5 57.2 150 25.0 60.6 400 15.0 57.9 200 5.0 62.1 450 5.0 63.0 200 10.0 60.5 450 10.0 59.0 200 15.0 59.7 450 12.5 60.4 200 17.5 58.6 450 15.0 62.1 200 20.0 58.9 500 5.0 62.5 250 5.0 61.3 500 10.0 60.9 250 10.0 59.7 500 12.5 62.4 250 15.0 59.2 500 15.0 61.7 250 17.5 57.7
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表 3 高斯拟合模型和洛伦兹拟合模型参数1)
Table 3 Parameters of Gaussian fitting model and Lorentz fitting model
模型 Model z0 A xc w1 yc w2 高斯拟合 Gaussian fitting 62.10±0.29 −7.39±0.64 321.61±6.22 77.98±8.13 14.03±0.47 5.30 ±0.64 洛伦兹拟合 Lorentz fitting 62.69±0.40 −8.65±0.78 323.40±5.71 85.23±13.64 14.16±0.49 6.78 ±1.13 1)表中数据为平均值±标准误；z0：零点偏移量，A：模型峰值高度，xc：模型峰x轴中心位置坐标值，w1：x轴方向模型峰宽度，yc：模型峰y轴中心位置坐标值，w2：y轴方向模型峰宽度 1) Data in the table are mean ± standard error; z0: Zero offset, A: Model peak height, xc: Coordinate value of model peak x-axis central position, w1: Width of model peak in x-axis direction, yc: Coordinate value of model peak y-axis central position, w2: Width of model peak in y-axis direction
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表 4 表面张力拟合曲线统计量
Table 4 Fitting curve statistics of surface tension
模型 Model 均方根误差 RMSE 决定系数 R2 调整后R2Adjusted R2 迭代次数 Iterations 拟合状态 Fitting state 多项式拟合 Polynomial fitting 1.412 6 0.794 1 0.736 9 10 拟合 Fitting 高斯拟合 Gaussian fitting 1.148 5 0.809 4 0.786 1 14 拟合 Fitting 洛伦兹拟合 Lorentz fitting 1.105 9 0.816 4 0.794 0 12 拟合 Fitting
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表 5 磁化除草剂溶液雾滴粒径测试结果
Table 5 Test results of aerosol droplet size of magnetized herbicide solution
磁场强度/mT Magnetic field intensity 磁化时长/min Magnetization time 雾滴粒径/μm Droplet size 磁场强度/mT Magnetic field intensity 磁化时长/min Magnetization time 雾滴粒径/μm Droplet size 50 5.0 121.19 250 20.0 113.37 50 10.0 120.71 300 5.0 116.74 50 15.0 119.03 300 10.0 111.43 50 17.5 119.24 300 15.0 110.35 50 20.0 118.88 300 17.5 111.02 100 5.0 118.37 300 20.0 111.20 100 10.0 117.96 350 5.0 112.16 100 15.0 116.99 350 10.0 109.65 100 20.0 114.07 350 15.0 108.75 100 25.0 113.86 350 17.5 110.67 150 5.0 117.91 350 20.0 110.68 150 10.0 115.44 400 5.0 115.03 150 15.0 115.55 400 10.0 113.30 150 20.0 112.47 400 12.5 110.94 150 25.0 114.12 400 15.0 111.60 200 5.0 112.93 450 5.0 117.16 200 10.0 112.72 450 10.0 112.68 200 15.0 112.33 450 12.5 115.71 200 17.5 111.29 450 15.0 115.97 200 20.0 111.07 500 5.0 112.65 250 5.0 115.87 500 10.0 111.98 250 10.0 111.98 500 12.5 110.63 250 15.0 112.51 500 15.0 111.77 250 17.5 111.32
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表 6 模型验证分析
Table 6 Model validation analysis
磁化时长/min Magnetization time 实测雾滴 粒径/μm Measured droplet size 理论雾滴 粒径/μm Theoretical droplet size 相对误差/% Relative error 5.0 113.22 112.45 0.68 10.0 110.16 109.07 0.99 15.0 108.54 109.39 0.78 20.0 110.78 110.59 0.17
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