Numerical analysis of mixing performance of mixing section in pin-barrel single-screw extruder

Using the finite elements method, numerical simulations of the flow field of a rubber melt in the mixing sections of a conventional full-flight single-screw extruder and a pin-barrel single-screw extruder were carried out. Particle tracking analysis was used to statistically analyze the mixing state of the rubber melt in the mixing section with pin and that without pin. The mixing performance of both types of mixing section was quantitatively evaluated. The results show that the pins partially disorganize the particle trajectories, change the particle moving directions, and enhance the mixing performance. The particle residence time is longer in the mixing section with pins than in the mixing section with no pin, leading to better mixing in the former. The distributive mixing of particles in both types of mixing section was statistically analyzed. The pins increase the efficiency of stretching and the time-averaged efficiency of stretching, and hence the mixing efficiency. However, further increase in the number of pins does not necessarily enhance the mixing performance.