Optimization Study On Cleaning System Of Leafy Vegetable Planting Tray

Leafy vegetable industrial production technology has rapidly developed because of its advantages in many aspects.In this technology,the full mechanization and automatic cleaning of leafy vegetable planting tray is a very important link.Water jet cleaning technology has gradually replaced manual cleaning,mechanical cleaning and chemical cleaning due to its advantages such as less environmental pollution,strong equipment versatility,high cleaning efficiency,and low cleaning costs,and has been rapidly developed and widely used.Aiming at the problem of cleaning the tray,according to the water jet cleaning theory,a bench cleaning test and a numerical simulation test were used to optimize the cleaning process and improve the cleaning ability.Combined with the actual production of leafy vegetables,a practical cleaning device for leafy vegetable planting tray was designed.After trial-manufacture and commissioning,production verification were carried out in the leafy vegetable factory production workshop,the evaluation criteria and sensory evaluation methods for cleaning effects were proposed.This research realized the full mechanization and automation of leafy vegetable planting plate cleaning,which will promote the application of leafy vegetable industrial production technology.The main research contents are as follows:(1)Based on the actual production of leafy vegetables,a cleaning test bench was set up.According to the actual research status of water jet experiments,a cleaning coating was prepared,and the cleaning area was measured with ImageJ image processing software.With the cleaning area percentage as an indicator,single-factor tests such as the cone angle,target distance,impact angle,and fan nozzle outlet diameter were carried out.The optimal value of each factor obtained by the experiment is that the water jet cone angle is selected to be 65 °,the water jet preferred target distance is in the range of 20-50 mm,the water jet impact angle is preferably in the range of 0-30 °,and the fan nozzle outlet aperture is selected to be 3.5mm.Within the preferred range determined by the single factor test,using the target distance and impact angle as factors,and the cleaning area percentage as an indicator,a binary quadratic regression orthogonal combination test scheme was implemented,and data wereobtained through the bench cleaning test.With the help of DesignExpert software,a regression equation between the response value and the two factors was established,and the confidence interval was given by a three-term test.Furthermore,based on the regression equation,taking the maximum cleaning area percentage as the optimization target,the optimized target distance is 45 mm and the impact angle is 5 °.(2)The internal structure of the fan-shaped nozzle was cast using molten wax,and the internal structure parameters of the nozzle were obtained by image measurement.Using Solidworks software to complete the calculation of the fan nozzle water jet calculation area modeling,Gambit software uses a macro unstructured meshing method to spatially discretize the calculation area,using standard k-? turbulence model and VOF multiphase flow model,using Fluent software uses the finite volume method to establish discrete equations,and uses a first-order upwind style in the interpolation calculations of momentum,volume fraction,turbulent flow energy,and turbulent dissipation rate.The initial conditions of the flow field are as followes: the calculation area was full of air,a 0.4MPa pressure inlet boundary and a 0.1MPa pressure outlet boundary were set.Above all,a fan nozzle water jet calculation model was established.The flow field iterative solution method uses the simple algorithm to calculate the convergence.In order to verify the correctness of the calculation model,theoretical calculation and experimental verification were carried out.The error between the simulation value of the water jet velocity at the exit of the fan nozzle and the theoretical value is 7%;the error between the simulation value and the test value of the water jet flow at the fan nozzle is 5%.By means of numerical simulation to control the misunderstanding of the test and improve the repeatability of the test,the fan jet water jet flow field was visualized,the fan jet water jet structure was analyzed,and the target surface impact pressure and shear stress distribution were obtained.(3)Through the numerical simulation calibration of the water jet of the fan nozzle,the coverage width of the target surface impact pressure threshold 10000 Pa can be determined as a quantified index to characterize the cleaning ability,thereby carrying out numerical simulation experiments.By analyzing the influence of target distance and impact angle on the cleaning ability,the relationship between the working parameters of the fan nozzle and the cleaning ability is obtained,which can guide the setting of the working parameters of the fan nozzle.Through the numerical simulation experimental research on the nozzle arrangement distance,it is determined that the nozzle arrangement distance is 57 mm.(4)According to the setting parameters and reference values of the process parameters of the fan nozzle water jet cleaning system,combined with the actual production of leafy vegetables in the factory,the mechanical structure design of the planting plate cleaning device and the design of the water circulation system were completed.After production verification of the colony disc cleaning system,the outlet diameter of the fan nozzle was selected to be 3.5mm,the water jet cone angle was selected to be 65 °,the water jet target distance was 60 mm,the water jet impact angle was 5 degrees,and the distance between the two nozzles was 57 mm.In this study,the strength limit for the removal of the scale layer of the planting tray was the impact pressure of 10,000 Pa.(5)During the production verification process,the design of the cleaning device was improved,and the comparison between the man-machine test and the production conditions of the planting tray was carried out.The influence of different treatment conditions,such as improved design,manual cleaning,and continuous production conditions,on the cleaning effect was analyzed,and the evaluation criteria and sensory evaluation methods for cleaning effects were proposed.The evaluator completes the scoring table for different processing conditions based on the evaluation criterion table.The scoring table summarizes the comprehensive evaluation scores of each processing condition.According to the sensory evaluation results of cleaning effects,the efficiency of the cleaning device is better than manual cleaning.The cleaning effect of the planting tray under continuous production conditions meets production requirements.After improving the design,the cleaning effect of the cleaning device in this study was further improved.After production verification,the cleaning effect of the cleaning device in this research reached the requirements of industrialized leafy vegetable production.