Calibration and Experimental Validation of Discrete Element Parameters for Cotton Stalk Phloem, Xylem and Pith

The xylem of cotton stalks is a high-quality biomass feedstock with strong high-value utilization potential. However, existing studies lack accurate calibration of discrete-element parameters for separated stalk components, which limits the optimization of the design of separation equipment. This study uses phloem, xylem, and pith of cotton stalks as research objects and measures the intrinsic physical and mechanical parameters and paired contact parameters of the three components. Given the strong agglomeration tendency of crushed phloem long fibers, the Hertz–Mindlin with JKR model is used to calibrate the adhesion parameter. The applicability of this model to low-moisture, high-aspect-ratio fibrous materials is verified, and the measured equivalent surface energy of phloem reaches 2.887 J/m2. CFD-DEM-coupled air separation verification is performed. The relative errors of xylem impurity content and loss rate between simulation and experiment are both below 10%, confirming the good reliability of the calibrated parameters. This study provides data to support the development of cleaning equipment for crushed cotton stalks. It provides a methodological reference for calibrating discrete-element parameters for similar long-fiber biomass materials.