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  • 1
    Electronic Resource
    Electronic Resource
    Energy Balance of Low Hydrated Starches Transition Under Shear (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 67 (2002), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Moistened (25% to 30% total basis) starches were processed on a pre-shearing rheometer under controlled conditions of temperature, residence time, and shear rate. The specific mechanical energy (30 to 1000 J.g-1) was measured and starch transformations assessed. The conversion of compacted native starch into a suspension of granule fragments in a melt was modeled by a simplified energy balance of the shearing zone. A theoretical fragmentation mechanism was proposed with a critical fracture energy of 125 J.m-2. The computed mechanical energy and time necessary for achieving this transition varied in agreement with experimental results, for different operating conditions and starch botanical origins. Interparticle friction influenced granule fragmentation, whereas crystal melting was associated with viscous dissipation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.2002.tb10301.x
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  • 2
    Electronic Resource
    Electronic Resource
    A Basic Model for a Twin-Screw Extruder (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 54 (1989), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A model based on solving thermal balance and Stokes equation in a corotating twin-screw extruder with deep screw channels was developed. The present stage of the model described the evolution of temperature in the conveying section and the isothermal evolution of pressure in the melt pumping and reverse screw elements, with a Newtonian viscosity adapted to each part of the screw; residence time distribution in the whole extruder was also computed. Experimental validation was carried out on a pilot scale twin-screw extruder CLEXTRAL BC 45 fed with maize starch. Good agreement was found between the theoretical and actual temperature and pressure profiles, as well as with residence time distribution. In standard operating conditions (30 kg/hr, 200 rpm), the pressure generation in one C-shaped chamber was computed to be about 2.2 MPa, while pressure drops were about 0.3 MPa (intermeshing zone) and 0.5 MPa (reverse screw element) while the major part of the residence time per unit of screw length was spent in the reverse screw element.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1989.tb07941.x
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  • 3
    Electronic Resource
    Electronic Resource
    Theoretical Computation of the Isothermal Flow Through the Reverse Screw Element of a Twin Screw Extrusion Cooker (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 53 (1988), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model of the flow of molten starch through the reverse screw element of a twin screw extrusion-cooker was proposed. The assumptions included isothermicity, Newtonian flow in each part of the reverse screw element and quasi-steady geometry. The theoretical approach is based on solving Stokes equations in the direct screw element and then on writing flow rate conservation in each part of the reverse screw element. The various flow rates, the pressure drop and the residence time distribution through the reverse screw element were computed for a CLEXTAL BC 45 twin screw extruder under different operating and geometrical conditions; good agreement was found when comparing these results with previous experimental work. The pressure drop through the reverse screw element was low (0.5–1.0 MPa); the flow rates in the different channels of the reverse screw element were important compared to the total feed rate of the extruder (two to three times larger) which might explain the broadening of the residence time distribution in the reverse screw element.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1988.tb07769.x
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  • 4
    Electronic Resource
    Electronic Resource
    Computer simulation of starchy products' transformation by twin-screw extrusion
    Amsterdam : Elsevier
    Journal of Food Engineering 19 (1993), S. 1-31 
    Details
    ISSN: 0260-8774
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0260-8774(93)90059-S
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  • 5
    Electronic Resource
    Electronic Resource
    An improved thermal model for the solid conveying section of a twin-screw extrusion cooker
    Amsterdam : Elsevier
    Journal of Food Engineering 15 (1992), S. 167-185 
    Details
    ISSN: 0260-8774
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0260-8774(92)90049-C
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  • 6
    Electronic Resource
    Electronic Resource
    Computation of residence time and energy distributions in the reverse screw element of a twin-screw extrusion-cooker
    Amsterdam : Elsevier
    Journal of Food Engineering 16 (1992), S. 215-237 
    Details
    ISSN: 0260-8774
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0260-8774(92)90035-5
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  • 7
    Electronic Resource
    Electronic Resource
    Determination of the wall slip velocity in the flow of a SBR compound (1992)
    Springer
    Rheologica acta 31 (1992), S. 565-574 
    Details
    ISSN: 1435-1528
    Keywords: Wall slip ; rubber ; Mooney method ; slit die
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Rubber compounds are known to exhibit slip at the wall in particular flow conditions. The slip velocity is usually determined by using the classical Mooney method. The rheological behavior of a styrene butadiene rubber (SBR) compound was studied with three different rheometers. Biconical rotational, capillary and slit die rheometers were used to define the true viscous behavior of the compound and the slip velocity. It was shown that it was impossible to apply the Mooney method to our experimental data. New characterizations were thus developed for both capillary and slit die experiments. They were based on the dependency of the slip velocity on the local flow gap. Contrarily to the Mooney method, they provided physically acceptable results and led to a power-law relationship between wall slip, wall shear stress and local geometry of the flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00367011
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  • 8
    Electronic Resource
    Electronic Resource
    A specific slit die rheometer for extruded starchy products. Design, validation and application to maize starch (1993)
    Springer
    Rheologica acta 32 (1993), S. 465-476 
    Details
    ISSN: 1435-1528
    Keywords: Slit die ; rheometer ; extrusion ; starch ; thermomechanical treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract A novel in-line rheometer, called “Rheopac”, has been designed and built in order to study the rheological behaviour of starchy products or, more generally, of products sensitive to a thermomechanical treatment. It is based on the principle of a twin channel, using a balance of feed rate between each of them, in order to make local shear rate vary in the measuring section without changing the flow conditions into the extruder. A wide range of shear rate could be reached and measurements were performed more swiftly than with a classical slit die. The viscous behaviour of maize starch was studied by taking into account the influence of the thermomechanical history, which modified the starch degradation and thus led to important variations in the viscosity. Experimental results were satisfactorily compared to previously published models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00396177
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  • 9
    Electronic Resource
    Electronic Resource
    Rheological behaviour of low moisture molten maize starch (1987)
    Springer
    Rheologica acta 26 (1987), S. 570-576 
    Details
    ISSN: 1435-1528
    Keywords: Pre-shearingrheometer ; maizestarch ; molten phase ; thermomechanical treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The rheological behaviour of a molten maize starch in low hydrated phase was investigated using a pre-shearing rheometer. This apparatus enables one to impose well-characterized thermomechanical treatment on the product before viscosity measurement. The influence of temperature, moisture content and intensity of the treatment were studied. The rheological behaviour of the maize starch may be described by a power law with exponential dependences on temperature, water content and mechanical energy provided to the product before measurement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01333742
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  • 10
    Electronic Resource
    Electronic Resource
    A general non-isothermal model for one-dimensional multilayer coextrusion flows (1992)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 32 (1992), S. 213-220 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A general computation of multilayer coextrusion flow in a flat die geometry is presented. For any given number of layers of different polymers, characterized by their thermal and rheological behaviors, the model permits computation of velocity and temperature fields along the flow in constant or slightly varying geometries. The influence of different operating parameters (wall regulation temperature, flow rate, initial temperatures) on the interface positions and temperature evolutions is evaluated. Theoretical predictions of interface positions are in agreement with experiments carried out on an industrial multimanifold flat die.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760320308
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