FINITE-ELEMENT ANALYSIS OF MIXING PHENOMENA IN TANGENTIAL TWIN-SCREW EXTRUDERS FOR NON-NEWTONIAN FLUIDS

A flow analysis of non-Newtonian fluids inside co-rotating tangential twin-screw extruders is presented with the emphasis on mixing phenomena. A new simplified approach was proposed in modelling the flow, i.e. the flow in twin-screw extruders was considered as a sequence of flows in two regions: (i) the translation region (T-region), similar to a single-screw extruder; and (ii) the mixing region (M-region), representing the central part of twin-screw extruders. The flow has been assumed to be isothermal, steady-state and creeping. Furthermore, it was assumed that the velocity field does not change significantly in one co-ordinate (i.e. the down-channel direction in the case of the T-region and the axial direction in the case of the M-region) as compared with the other co-ordinate directions. Accordingly, a quasi-three-dimensional finite element method has been developed to analyse the flows in both regions. The mixing mechanisms inside the T-and M-regions were analysed and the inter-channel mixing in the M-region was quantified. The residence time distribution and performance characteristic of a single screw with a self-wiping profile were also calculated.X1111sciescopu

NUMERICAL AND EXPERIMENTAL STUDIES OF THE FLOW IN THE NIP REGION OF A PARTIALLY INTERMESHING CO-ROTATING TWIN-SCREW EXTRUDER

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A new energy conservation scheme for the numeric study of the heat transfer in profile extrusion calibration

In this work, a new second-order conservative finite volume scheme using the cell-to-vertex interpolation is proposed to solve the heat transfer problem involving discontinuous solution and discontinuous materials properties. We apply the method to a thermoplastic extrusion process where a dry calibration is used to cool down a polymer tape. One of the major difficulties in the modelling is to prescribe the adequate value for the heat transfer coefficient between the polymer and the calibrator. To this end, we define an optimization procedure coupled with the new finite volume method to evaluate the heat transfer coefficient at the polymer-calibrator interface from experimental data.This research was financed by FEDER Funds through Programa Operacional Factores de Competitividade - COMPETE and by Portuguese Funds through FCT - Fundacao para a Ciencia e a Tecnologia, within the Projects PEst-OE/MAT/UI0013/2014, PTDC/MAT/121185/2010, and UID/CTM/50025/2013. The second author was also financed by project FCT-ANR/MAT-NAN/0122/2012.info:eu-repo/semantics/publishedVersio