Mixing efficiency in a pin mixing section for single-screw extruders

Non-Newtonian, non-isothermal 3D finite-element simulation of mixing perfor mance in a pin mixing section with different axial gaps in the pins has bee n carried out according to their realistic configurations. The quantitative evaluation of mixing ability was based on the theory of kinematics of flui d mixing. To learn and to compare the local mixing performance in a standar d screw and a pin mixing section, the local mixing efficiency distribution proposed by Ottino was calculated. Also, the RTDs of these mixers were calc ulated in an attemt to measure mixing. The integration of the two, namely, the integrating local mixing efficiency along a number of particle pathline s from entrance to exit, together with statistical treatment, which was ref erred as integral mixing efficiency, then gives a quantitative judgment of the total mixing ability of a continuous mixer. The calculated results show ed a nonlinear dependence of the mixing ability of a pin mixing section on the axial gap of the pins. Finally, the calculation results were compared w ith the experimental ones obtained in our previous study.