Heat transfer and viscous polymer melting capacity correlation in self-controlled torsion induced extrusion

A novel design concept of torsion screw configuration has been proposed to improve polymer melting ability. The heat transfer and melt flow behavior of a two-phase viscous polymer, induced by torsion elements in a screw compression section, were analyzed with the computational fluid dynamics simulation. It has been found that screws with added torsion elements have larger Nusselt number and liquid mass fraction, and shorter melting zone compared to that of a conventional screw. The heat transfer and melting capacity improve with the increasing number of torsion elements and their preferred arrangement in the screw. A simplified simulation model of torsion and standard elements has been developed to predict the heat transfer and melt flow mechanism, and the simulation results are in consistent with the field synergy theory. The existence of torsional flow in the region of torsion channels increases the perturbation of the fluid, improves interaction between temperature gradient and velocity vectors, resulting in improved mass and heat transfer and rapid melting of polymers. Furthermore, the paper proposed a qualitative melt flow model of polymers in the channel of torsion element.