Parameter optimization of winnowing equipment for machine-harvested Lycium barbarum L.

To accurately and efficiently remove unripe fruit, flowers, leaves, and other impurities in machine-harvested Lycium barbarum L., winnowing equipment for machine-harvested L. barbarum based on the principle that different materials have different flight coefficients was designed. To optimize the structure and working parameters of winnowing equipment, this study adopted the free flow resistance model to establish a horizontal airflow model based on C++ in Microsoft Visual Studio. A discrete element method (DEM) simulation of ripe fruit in the horizontal airflow was performed using EDEM software. Results showed that the optimal parameters included an airflow speed of 5-6 m/s, input conveyor speed of 0.4-0.6 m/s, and input-output conveyor distance of 260-270 mm. We used three factors and three levels in a quadratic orthogonal rotation design to establish mathematical models regarding the rate of impurity change and the clearance rate of ripe fruit based on the airflow speed, input conveyor speed, and input-output conveyor distance. We also analyzed the effects of all factors on the rate of impurity change and the clearance rate of ripe fruit. The optimal parameter combination was an airflow speed of 5.52 m/s, input conveyor speed of 0.5 m/s, and input-output conveyor distance of 265.04 mm. The field experiment showed that the rate of impurity change and the clearance rate of ripe fruit were 89.74% and 8.71%, respectively. Findings provide a design basis for future research on winnowing equipment for machine-harvested L. barbarum