Negative pressures in modelling rotating polymer processing machinery are meaningless, but they are telling something / A. Goger in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 2 (05/2014)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 2 (05/2014) . - p. 295-297 Titre : Negative pressures in modelling rotating polymer processing machinery are meaningless, but they are telling something Type de document : texte imprimé Auteurs : A. Goger, Auteur ; John Vlachopoulos, Auteur ; M. R. Thompson, Auteur Année de publication : 2014 Article en page(s) : p. 295-297 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Machines tournantes Matières plastiques -- Extrusion Pression -- Mesure Simulation par ordinateur Index. décimale : 668.9 Polymères Résumé : In the technical literature, some authors have reported calculation of negative pressures in simulations of twin screw extrusion and other types of processing, without giving any explanations. In the majority publications there is no mention of such meaningless results, even though theoretical considerations indicate that negative pressures could be obtained in the expansion region of drag flows through narrow non-parallel surfaces. The meaningless negative pressures are due to the application of single fluid theory to flow regions where bubbles would form, when the pressure drops below the vapor pressure of the liquid. This has been known for a long time from the study of lubrication bearings and related cavitation phenomena. It is argued that the boundary conditions should be carefully chosen for avoiding results in numerical simulations, which can never be reconciled with experimental pressure data. DOI : 10.3139/217.2706 En ligne : https://drive.google.com/file/d/16cYBjKfVI60cikbcNOeU95qTqmtH6uo5/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=21325 [article]

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Studying the effective thermal properties of solids in extrusion machinery using a discrete particle Simulation approach / P. A. Moysey in INTERNATIONAL POLYMER PROCESSING, Vol. XXIII, N° 3 (07/2008)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIII, N° 3 (07/2008) . - p. 301-311 Titre : Studying the effective thermal properties of solids in extrusion machinery using a discrete particle Simulation approach Type de document : texte imprimé Auteurs : P. A. Moysey, Auteur ; K. L. Cloet, Auteur ; M. R. Thompson, Auteur Année de publication : 2008 Article en page(s) : p. 301-311 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : In this paper, both experimental trials and numerical simulations are presented to improve our understanding of the heat transfer within granular polymer beds for systems with and without shear. Both amorphous polymer, polystyrene (PS), and a semi-crystalline polymer, high-density polyethylene (HDPE) of varying particle size from 6 mm to 25 mm were examined. The estimated effective thermal conductivity data from the experimental trials was found by fit to two simple semi-empirical models allowing readers to readily approximate the property based on porosity of the bed and solid thermal properties. Discrete particle simulations, i.e. DEM, were used to recognize the importance of heat transport through the stagnant interstitial gas phase in comparison to particle-particle conduction. The results underscore the importance of including an effective thermal conductivity for granular solids in an extruder when using continuum models. DOI : 10.3139/217.2118 En ligne : https://drive.google.com/file/d/1vgl5WeQykaIxi0MIdsxM7aFgwDzT2qqE/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2631 [article]

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