FLOW MODELING OF A POWER‐LAW FLUID IN A FULLY‐WIPED, CO‐ROTATING TWIN‐SCREW EXTRUDER1

Abstract

ABSTRACTThe two‐dimensional flow theory of a power law fluid in a fully‐wiped co‐rotating twin‐screw extruder was investigated under steady‐state, isothermal conditions. The important distinction between this approach and previously published theories (Denson and Hwang 1980; Booy 1980; Wang and White 1989; Lai‐Fook et al. 1989, 1991) is that actual boundary conditions were used instead of boundary conditions based on the parallel plate model developed for single screw extruders. The generalized screw curves constructed for both double‐lead and single‐lead screw elements were similar in shape to those published for single screw extruders with rectangular channels. Noticeable increases in the closed discharge pressure and the open discharge flow rate were observed, which are the result of the screw geometry. Experimental results with corn meal were in agreement with theoretical predictions for single‐lead screw elements. Theoretical predictions for double‐lead screw elements using the new solution also showed reasonable agreement with experimental data from published literature after the incorporation of the intermeshing effect.