Prediction of temperature profiles in twin screw extruders

Ibrahim O. Mohamed, Robert Y. Ofoli

    Research output: Research - peer-reviewArticle

    • 4 Citations

    Abstract

    A model incorporating viscous dissipation effects and a heat transfer coefficient based on the Brinkman and Graetz numbers is presented for predicting the temperature profiles of non-Newtonian food doughs in a twin-screw extruder, assuming uniform product temperatures in the direction normal to the screw shafts. Experimental measurements were obtained to evaluate the model for three screw configurations: 30° forwarding paddles (30F), feed (two-start or double-flighted) screws and single-start (single-flighted or single-lead) screws. Model predictions were well within engineering accuracy for 30F paddles and feed screws under all experimental conditions. Predictions for single-start screws were inaccurate, with deviations of up to 50%. In general, results indicate that the one-dimensional energy equation is sufficient for heat transfer analysis of extruder sections configured with mixing paddles and feed screws, particularly at high flow rates, high RPM, or combinations of the two variables. However, the level of mixing provided by single-start screws over the RPM and flow rates used in this study does not justify the assumption of uniform temperatures in the transverse direction. For these screws, at least a two-dimensional formulation of the energy equation must be used.

    LanguageEnglish (US)
    Pages145-164
    Number of pages20
    JournalJournal of Food Engineering
    Volume12
    Issue number2
    DOIs
    StatePublished - 1990

    Profile

    extruders
    screws
    temperature profiles
    prediction
    Temperature
    Hot Temperature
    Direction compound
    Food
    Lead
    energy
    temperature
    heat transfer coefficient
    heat transfer
    dough
    engineering

    ASJC Scopus subject areas

    • Food Science

    Cite this

    Prediction of temperature profiles in twin screw extruders. / Mohamed, Ibrahim O.; Ofoli, Robert Y.

    In: Journal of Food Engineering, Vol. 12, No. 2, 1990, p. 145-164.

    Research output: Research - peer-reviewArticle

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    abstract = "A model incorporating viscous dissipation effects and a heat transfer coefficient based on the Brinkman and Graetz numbers is presented for predicting the temperature profiles of non-Newtonian food doughs in a twin-screw extruder, assuming uniform product temperatures in the direction normal to the screw shafts. Experimental measurements were obtained to evaluate the model for three screw configurations: 30° forwarding paddles (30F), feed (two-start or double-flighted) screws and single-start (single-flighted or single-lead) screws. Model predictions were well within engineering accuracy for 30F paddles and feed screws under all experimental conditions. Predictions for single-start screws were inaccurate, with deviations of up to 50%. In general, results indicate that the one-dimensional energy equation is sufficient for heat transfer analysis of extruder sections configured with mixing paddles and feed screws, particularly at high flow rates, high RPM, or combinations of the two variables. However, the level of mixing provided by single-start screws over the RPM and flow rates used in this study does not justify the assumption of uniform temperatures in the transverse direction. For these screws, at least a two-dimensional formulation of the energy equation must be used.",
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