| In recent years,with the negative growth of pesticide application in China,green prevention and control technologies such as reducing pesticide application,increasing efficiency and alternative utilization have been greatly developed.Strong oxidizing free radical solution has emerged in the field of agricultural plant protection due to its environmental friendliness,remarkable killing effect on pathogenic bacteria,easy preparation and safety.In this paper,on the basis of self-propelled boom sprayer,an in-situ synthesis spray system of strong oxidizing free radical solution was designed and developed,which was composed of micro-nano bubble generator,multistage pump,diaphragm pump and Venturi tube.Through ANSYS numerical calculation and Design-Expert response surface design,the internal structure and operation parameters of the generator were optimized,the solution preparation parameters were optimized,the performance test of the spray system,the static and dynamic mechanical analysis of the key components of the sprayer,the development and implementation of the control system and the field control test of rice diseases were carried out,and the large-scale synthesis system of strong oxidizing free radical solution was optimized.A spray system for in-situ synthesis of strong oxidizing free radical solution was formed.The main conclusions of this paper are as follows :(1)The synthesis process of strong oxidizing free radical solution was determined.On the basis of scheme determination,the synthesis system construction and equipment creation of strong oxidizing free radical solution were completed.Through the analysis of the results of the numerical calculation of the internal flow field of the micro-nano bubble generator,which is the core component of the micro-nano bubble generator,the optimal working pressure of the micro-nano bubble generator is 0.35 MPa,the diameter of the flow chamber is 5mm,and the gap between the disc-shaped cracks is 2mm.It provides guarantee for efficient gas-liquid mass transfer;the optimal process parameters of the strong oxidizing free radical solution were determined by response surface test as follows : ozone inlet volume3L/min,p H5.2,potassium persulfate dosage 250mg/L,which provided process parameters for large-scale application of the synthesis process of strong oxidizing free radical solution.(2)According to the analysis of the operation requirements of the typical field crop planting mode,the design of the spray system suitable for the prevention and control of field crop diseases was completed through the selection of relevant equipment and the calculation of spray volume.The results of spray uniformity and stability test show that the spatial variation coefficient and time variation coefficient of the spray system are 3.120% and 2.844%,respectively,when the Blue Ao FPV03 nozzle is used and the spray pressure is 0.3MPa.At this time,the average TRO concentration of spraying solution at the nozzle was 2.59mg/L,and the spraying system could conduct field plant protection operation with good working quality.ANSYS simulation software was used to carry out static and dynamic mechanical analysis on the two key structures of the sprayer chassis and support frame.The maximum stresses of the chassis and support frame were 91.179 MPa and29.914 MPa,respectively,and the maximum deformations were 0.3548 mm and0.12602 mm,respectively,which were far less than the allowable stress.At the same time,the first 10 modes,natural frequencies and maximum amplitudes of chassis and support frame meet the analysis requirements.(3)By analyzing the control requirements of the strong oxidizing free radical solution preparation device,the four control requirements of manual preparation function control,automatic preparation function control,liquid level control and human-computer interaction control are determined,and the design goal of the control system is clarified.Combined with the structure design scheme,the main hardware of the control system is selected.The PLC model and the required module types are determined to ensure that they meet the control requirements;according to the target range of each parameter,the appropriate sensor type and control switch are selected,and the hardware equipment of the human-computer interaction interface is selected.Based on the analysis results,the hardware structure of the control system is built.According to the hardware structure of the control system,the PLC program design and the MCGS configuration design of the touch screen are carried out,and the preparation of the control program and the design of the touch screen control interface are completed.The remote monitoring of the preparation device is realized.(4)In the rice control experiment,the results showed that the single application of pesticides to disperse Cnaphalocrocis medinalis was limited,and the combined use of strong oxidizing free radicals and pesticides could better control the pest of Cnaphalocrocis medinalis.Considering the reduction of pesticides,pesticides should be sprayed at tillering stage and strong oxidizing free radicals solution should be sprayed at jointing and booting stage in actual production,and the control effect was 65.53%.The control effect of pesticides on rice false smut was limited due to the lack of broad-spectrum,and the spraying of strong oxidizing free radical solution on both rounds of application could almost completely control rice false smut,with the control effect of 97.85%.At the same time,strong oxidizing free radical solution had no adverse effects on chlorophyll SPAD value,net photosynthetic rate,intercellular carbon dioxide concentration and transpiration rate of rice,and had positive effects on some agronomic traits(panicle number,effective panicle number,plant height,panicle length,grain weight per plant)of rice. |
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