黑水虻处理的猪粪有机肥离散元仿真模型参数标定

为准确快速获取黑水虻处理的猪粪有机肥颗粒的离散元仿真模型参数,该研究采用圆筒提升堆积物理试验与EDEM仿真结合的方法,选取"Hertz-MindlinwithJKR"作为接触模型,以堆积角为响应值,基于响应面法优化标定了黑水虻处理的含水率为43.6%的猪粪有机肥仿真参数。采用Design-Expert8.0.6设计Plackett-Burman试验,筛选出对堆积角有显著影响的参数,即有机肥泊松比、有机肥颗粒密度、有机肥-有机肥滚动摩擦系数。通过最陡爬坡试验确定了显著参数的最优值区间,进一步以有机肥堆积角为响应值,基于Box-Behnken试验获得堆积角与显著性参数的二阶回归模型,以物理试验测得的堆积角为响应目标,针对显著性参数进行寻优,得到最佳组合:有机肥泊松比0.11、有机肥颗粒密度1 703 kg/m~3、有机肥-有机肥滚动摩擦系数0.13。运用最佳参数组合进行仿真分析,得到堆积角均值为38.61°,与物理试验测得的堆积角相对误差为1.88%,且堆积形状具有较高相似性,无明显差异,表明标定的参数准确,研究结果可为黑水虻处理猪粪后的有机肥相关收集与筛分机械的设计提供理论参考。

Parameter calibration of discrete element simulation model for pig manure organic fertilizer treated with Hermetia illucen

Pig manure treated by the Hermetia illucen was an organic fertilizer, to obtain the contact parameters of organic fertilizer accurately and quickly,, this work combine the method of a cylindrical lifting physical test with discrete element method, and simulation parameters of organic fertilizer of Hermetia illucen treated with pig manure with moisture content of 43.6% was calibrated. Firstly, a physical test was carried out. The diameters of organic fertilizer of Hermetia illucen treated with pig manure particles were between 1.6 and 2.6 mm, and an steel cylinder with an inner diameter of 40 mm and a height of 120 mm was used. The organic fertilizer of Hermetia illucen treated with pig manure particles were filled into the cylinder, and then lifted with a speed of 0.03 m/s. The angle of repose of the organic fertilizer of Hermetia illucen treated with pig manure was measured and the test was repeated for five times, as the mean angle of repose was 39.35°, and the variable coefficient was 0.75%. Secondly, the simulation test was carried out. Hertz-Mindlin with JKR contact model was selected from the system, and the discrete element simulation of the physical stacking test was performed by EDEM. Since the organic fertilizer of Hermetia illucen treated with pig manure particles were near-spherical, the basic model of the software default was adopted to simulate organic fertilizer of Hermetia illucen treated with pig manure granules. Therefore, a basic sphere model with a radius of 1 mm was used and the three-dimension geometry model built by Solid Works was imported into the simulation software, with the cylinder lifting speed was 0.03m/s, the fixed time step was 22% of Rayleigh time step, and the target save interval was 0.01 s. Repose angle of organic fertilizer of Hermetia illucen treated with pig manure was taken as response value based on the Design Expert software8.0.6, and P-BD (Plackett-Burman Design) test was used to screen 10 initial parameters. It was found that not all discrete element model parameters of organic fertilizer of Hermetia illucen treated with pig manure had significant impact on the angle of repose, so a screening process was made through Plackett-Burman Design. The results showed that organic fertilizer of Hermetia illucen treated with pig manure poisson ratio, organic fertilizer of Hermetia illucen treated with pig manure particle density, and organic fertilizer of Hermetia illucen treated with pig manure organic fertilizer of Hermetia illucen treated with pig manure rolling friction coefficient had significant impact on angle of repose. The best range of three significant influencing factors was determined by the steepest climbing test, the other seven factors in this test were the intermediate values of the initial range, and the three significant parameters gradually were increased and decreased until the relative error between the simulated value and the physical test value reached the minimum. Thirdly, the accumulation angle of organic fertilizer of Hermetia illucen treated with pig manure was taken as the response value, Box-Behnken Design test was used to fit the test results using regression analysis, and the accumulation angle regression model was obtained. The determination coefficient R2=0.988 1 and the correction determination coefficient R2adj =0.966 7 were both close to 1, indicating the model fitted better. The precision was 21.510, the variable coefficient was 1.78% and the lack-of-fit was non-significant, which showed that the regression model was very significant, and the accumulation angle could be predicted according to the model. the regression model was optimized, and the optimal values of three significant factors were obtained: organic fertilizer of Hermetia illucen treated with pig manure poisson ratio was 0.11, organic fertilizer of Hermetia illucen treated with pig manure particle density was 1 703 kg/m3, and the coefficient of rolling friction of organic fertilizer of Hermetia illucen treated with pig manure particleorganic fertilizer of Hermetia illucen treated with pig manures was 0.13. The simulation analysis was performed by the optimal parameter combination. The average repose angle was 38.61o, and the relative error between the repose angle and the experiment was 1.88%. which meant that the calibration parameters were accurate. The result can provide theoretical basis for the design of organic fertilizer of Hermetia illucen treated with pig manure related collecting and sieving machinery.