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PROCESS web version (v. 1.09)

Aim and physical principles

This program simulates the diffusion of 2,5-dimethoxyacetophenone (DMA= C.A.S No. 1201-38-3, a model highly diffusive molecule) within different plastic films (thickness l_P) including a symmetric functional barrier (relative thickness fb) during subsequently:
  • i) an isothermal extrusion process (residence time whithin the dye te, temperature Te)
  • ii) and a convective cooling at room temperature (convective heat transfer coeffiecient hc).

  • You can simulates in almost real times any combination of the five parameters for 13 different polymers. For each polymer, two parameters are tested wihtin a precribed range of values while the three others are kept constant.

    Assumptions (consistent with experiments carried out with DMA):

  • diffusive mass transport
  • diffusive heat transfer (constant effective thermal diffusivity including source terms = 1.6e-7 m2.s-1 for all polymers)
  • impervious boundary conditions are assumed (no contact with food, only the contamination of the functional barrier and the external surface is considered)
  • mass transport activated by temperature according to Arrhenius relationship
  • Inputs/outputs

    NAME DESCRIPTION
    l_P
    thickness
    SI unit = m
    valid range between 10 µm and 3 cm
    fb
    relative tickness of the functional barrier
    no unit
    in the current version, only 33% is possible

    Te

    extrusion temperature (dye temperature)
    SI unit C
    valid range depends on the polymer
    EP [140 230] C
    EVA [100 230] C
    EVOH [140 260] C
    HDPE [100 230] C
    LDPE [100 230] C
    LLDPE [100 230]C
    PA [170 270]C
    PAN [150 250]C
    PET [240 330]C
    PP [170 270]C
    PS [130 260]C
    PVC [130 260]C
    PVC [100 230]C
    te
    residence time in the dye
    SI unit s
    valid range between 0.1 and 30 s
    h
    convective heat transfer coefficient
    SI unit W.m-2.s-1
    valid range between 10 and 500 W.m-2.K-1
    % fb contamination
    rate of contamination of the functional barrier
    after 1 min of cooling (100%=equilibrium concentration)
    no unit
    valid range between 0 and 100 %
    % surface contamination
    rate of contamination of the external surfaces
    after 1 min of cooling (100%=equilibrium concentration)
    no unit
    valid range between 0 and 100 %

    PARAMETER FORM (see above for details)
    Invalid values are automatically set to the appropriate bounds.

    Polymer
    min
    value
    max
    value
    set
    value
    unit
    l_P
    fb
    33
    33
    33
    %
    Te
    C
    te
    s
    h
    W.m-2.K-1

    use CTRL+click to select the two variables to combine (if you select more, only the 2 first are considered)

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    2006 by INRA\Olivier Vitrac

     

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