| To improve the poor mixing performance of traditional single screw extruder in soybean protein processing, a coaxial allometric single screw structure based on cycloidal pin wheel drive was designed to improve the extrusion quality of single screw extruder. Taking the traditional single screw as the reference object, the corresponding geometric model was established by SolidWorks software. Based on the finite element method, the motion of soybean protein in the flow field was simulated by ANSYS/CFX software, and the flow field simulation data was extracted by CFD-Post software. The extrusion performance of the coaxial allometric single screw extruder was determined by comparing the pressure field, velocity vector field and streamline field, shear strain rate, and reflux coefficient. The results showed that the pressure-building capacity of the coaxial allometric single screw extruder was 1.22 times that of the traditional single screw extruder, the variable speed conveying section effectively slowed down the flow speed of the material, and the residence time of material in the variable speed conveying section of coaxial allometric single screw extruder was 1.86-2.19 times that of the traditional single screw extruder. The average shear strain rate of the traditional single screw extruder was 3.19 times that of the variable speed conveying section of coaxial allometric single screw extruder, and the coaxial allometric single screw extruder could effectively improve the shortening of the residence time of soybean protein due to shear thinning phenomenon. The reflux coefficient of coaxial allometric single screw extruder (0.46) was much higher than that of traditional single screw extruder, and the distribution mixing performance was better. In summary, the existence of a variable speed conveying section in the coaxial allometric single screw extruder enhances the pressure-building capacity, prolongs the residence time, and improves the distributed mixing performance. |
