Prediction of Flow, Heat Transfer, and Mixing Characteristics in Single-Screw Extrusion Based on Finite Element Analysis and an IPSO-BP Surrogate Model

Process parameters critically affect the flow, heat transfer, and mixing behaviors of rubber melts during single-screw extrusion. However, direct observation of the internal flow field is difficult, and high-fidelity numerical simulations are computationally expensive, limiting rapid analysis under multiple operating conditions. To address these challenges, a three-dimensional non-isothermal CFD model validated against experimental outlet temperature data was developed and coupled with an IPSO-BP surrogate model to establish a rapid prediction framework. The effects of screw speed, inlet temperature, and barrel temperature on flow, heat transfer, and local mixing characteristics were systematically investigated. The results indicate that screw speed predominantly affects melt flow and mixing behavior by enhancing drag flow, shear action, and internal heat transfer. Inlet temperature exerts the greatest influence on the mean outlet temperature, whereas barrel temperature primarily regulates the thermal state of the melt through wall heat transfer. Compared with the BP, GA-BP, PSO-BP, GPR, and XGBoost surrogate models, the IPSO-BP model demonstrated superior overall predictive performance, particularly achieving higher prediction accuracy and stability in predicting complex temperature responses. The proposed CFD–IPSO-BP framework provides an efficient tool for rapid prediction and optimization of EPDM single-screw extrusion processes.