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ISSN Online: 2377-424X

ISBN Print: 0-85295-345-3

International Heat Transfer Conference 10
August, 14-18, 1994, Brighton, UK

QUASI TWO-DIMENSIONAL AND FULLY TWO-DIMENSIONAL COMPUTER MODELS OF FLOW AND CONJUGATE HEAT TRANSFER IN THE METERING SECTION OF A SINGLE-SCREW PLASTICATING EXTRUDER : A COMPARATIVE STUDY

Get access (open in a dialog) DOI: 10.1615/IHTC10.3860
pages 331-336

Résumé

This paper presents a comparative study of a quasi two-dimensional and a fully two-dimensional model developed for the simulation of steady state flow and heat transfer in the metering section of a single-screw plasticating extruder. The conjugate heat transfer between the hot melt and the screw body has been modelled by assuming the latter as a semi-infinite body. The barrel is maintained at a fixed temperature and the material (LDPE) that is processed is assumed to follow non-Newtonian power law behaviour. The creeping flow and hydrodynamic bearing lubrication approximations have been made. The effect of viscous dissipation is included in the energy equation of the melt.
The two most important outcomes of the study are: (a) development of an efficient and novel numerical technique for computing pressure gradients accurately for the fully two-dimensional model and (b) showing that the flow becomes locally fully developed at a short distance from the inlet - thus confirming the earlier use of fully developed velocity profile in the quasi two-dimensional model as the inlet condition to be not physically unrealistic.
However, the main limitation of both the models is their inadequacy in predicting realistic screw surface temperature profile and pressure distribution in the downchannel direction. Thus, the need for a three-dimensional model that includes cross thermal convection effect is established.