ANALYSIS AND MODELING OF THE RESIDENCE TIME DISTRIBUTION IN INTERMESHING CO-ROTATING TWIN-SCREW EXTRUDERS BASED ON FINITE-ELEMENT SIMULATIONS

In the field of compounding and reactive extrusion the residence time distribution, among other factors, represents an important factor for the evaluation of the process behavior in co-rotating twin screw extru ders. The corresponding literature presents us with a lot of publicati ons regarding this subject. Mostly, these are empirical approaches to describe the residence time behavior or more experimental analyses. Th e existing description forms are often taken from the single-screw the ory and are applied to the twin screw extruder. This paper is meant to present a new analysis and description of the residence time behavior of a co-rotating twin screw extruder which is based on 3-D finite ele ment simulation for power law fluids. The residence time is thus deter mined and evaluated by means of streamlines taken from flow simulation . As a result the existing description formulations compared with expe rimental data for the operating parameters needed in practice are most ly out of the extent of validity. This is due to the high speed with a pre-defined melt throughput and the exceptional channel geometry of t he tightly intermeshing co-rotating twin screw extruder.