Design and Experimental Analysis of a Multi-Scale Fresh Tea Leaf Rotary Drum Screen Based on the DEM-RSM Method

Conventional rotary drum screens for fresh tea leaf classification suffer from persistent limitations, including screen aperture clogging, particle entanglement, and suboptimal operating parameter tuning, which impede the efficient and precise sorting of multi-grade fresh tea leaves. To address these challenges, this study presents a high-performance rotary drum screen design optimized via a coupled Discrete Element Method (DEM) and Response Surface Methodology (RSM) framework, validated through systematic experimentation. DEM simulations were employed to evaluate two screen aperture configurations: the conventional sequential "small-medium-large" layout and a novel alternating "small-medium-small-medium-large" design. Results demonstrated that the proposed layout effectively mitigates particle entanglement and reduces clogging, yielding superior screening performance. Single-factor experiments were conducted to define feasible operating ranges for drum rotational speed, inclination angle, and feed rate. Subsequent RSM experiments quantified the interactive effects of these parameters and established a regression model for separation efficiency. Optimization via Design-Expert software identified the optimal operating conditions: a rotational speed of 13 r/min, an inclination angle of 5.5°, and a feed rate of 300 fresh tea leaves (0.132 kg). Under these conditions, the average separation efficiency reached 70.49%. The DEM-RSM coupled approach presented herein provides a robust theoretical foundation for the structural innovation and parameter optimization of fresh tea leaf classification equipment, advancing the standardization and efficiency of primary tea processing.