A COUPLED CFD–DEM NUMERICAL STUDY OF THE AERODYNAMIC SORTING OF ZANTHOXYLUM BUNGEANUM SHELLS AND SEED-BEARING PARTICLES

Abstract

This study presents a particle-scale coupled CFD–DEM numerical approach for elucidating aerodynamic sorting mechanisms and optimizing process parameters. Non-spherical particle models were developed to represent the geometric and physical differences between shells and seed-bearing particles. The Stokes number, which characterizes the balance between aerodynamic drag and particle inertia, was identified as the primary determinant of sorting performance. Under the optimized conditions, a primary airflow velocity of 8.4 m/s, a secondary airflow velocity of 7.85 m/s, and a feed mass flow rate of 80 g/s, the system achieved a shell purity of 95.3% and a recovery rate of 58.2% when processing feedstock with an initial shell content of 5%. The results further revealed an inherent trade-off between purity and recovery. These findings provide a theoretical and numerical basis for the design and optimization of aerodynamic sorting equipment.