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Titre :
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Transient natural convection heat transfer to starch dispersion in a cylindrical container: Numerical solution and experiment
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Auteurs :
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W. Yang ;
M. Rao
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Type de document :
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article/chapitre/communication
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Année de publication :
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1998
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Format :
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p. 395-415
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Langues:
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= Anglais
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Catégories :
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SCIENCES FONDAMENTALES ET APPLIQUEES
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Mots-clés:
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AMIDON DE MAIS
;
DISPERSION
;
TRAITEMENT THERMIQUE
;
TRANSFERT DE CHALEUR
;
CONVECTION
;
RHEOLOGIE
;
MODELE NUMERIQUE
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Résumé :
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Center temperature-time profile of a 3.5% cornstarch dispersion heated in a vertical 303 x 404 can at 121°C compared favorably with finite element-based calculations with FIDAP computer simulation program. A thermo-rheological model based on experimental rheological data during starch gelatinization at 65-95 °C and combined with an assumed submodel for decreasing viscosity at 95-121 °C was used in the simulation Most of the deviation between experimental and calculated profiles was about 5%, but a higher deviation (20%) occurred at the beginning of the heating cycle was attributed to higher hearing rates similar to 14 °C min(-1) than the 3 °C min(-1) used in gathering rheological data, and to settling of starch granules. The deviation from experimental data was higher when the decreasing segment of the eta(a) versus temperature data were omitted in the simulation. Shear rates that were high early during heating decreased due to increase in apparent viscosity (eta(a)) as a result of starch gelatinization. With hearing, initially the velocity boundary layer was displaced away from the wall due to increase in the magnitudes of eta(a) of the STD close to the wall and subsequently moved closer to the wall due to decrease in eta(a).
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Source :
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Journal of Food Engineering, vol. 36
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