The Twin-screw Extruder Machine Thread Section Study Of The Numerical Simulation Of The Melting Process

In the process of twin-screw extrusion, the model of islands-sea is the coexistent form of the two-phase of solid and liquid, which has been seen usually in the melting process of solid pellets. As the two-phase of solid and liquid mixes with each other and flows forward with phase change, it is difficult to analyze and calculate directly. It is necessary to simplify the islands-sea model.In this paper, a simplified model of the islands-sea model was proposed, which was defined as middle model. For an element volume in the direction of the flow, two methods are adopted to investigate the melting problem in twin-screw extruders. The relationship between the radius of the solid pellets and time or the solid fraction and time can be determined, at the same time, the variation of the bulk temperature of the melt with time can also be obtained. The results derived from phase change fraction method are in familiar tendency with ones derived from the perturbation method.The relationship between the solid fraction and time derived from phase change fraction method is verified by experiment. The comparison shows that the calculating results are basically in agreement with the experimental ones.