Changelog

Version 2.0

  • New implementation of freezing model for a single container with spatial resolution (termed snowing). The model considers the gradients in temperature and in ice mass that form during freezing.

  • Currently supported features of the new spatial model:
    • Simulation of three different freezing process configuration:

      • Shelf-ramped freezing (commonly used in freeze-drying)

      • Vacuum-induced surface freezing (process variation where vacuum is applied to promote freezing through surface evaporation)

      • Jacket-ramped freezing (process variation where vial is surrounded by a temperature-controlled jacket

    • Simulation of different heat transfer boundary conditions (natural convection, conduction, thermal radiation, surface evaporation)

    • Simulation with different dimensionalities (0D, 1D, 2D)

Version 1.1

  • Support for 3D configurations, i.e. the arrangement of vials in three spatial dimensions. The package thus may be used to simulate the freezing of vials for storage in pallets, a common process in the manufacturing of biopharmaceuticals

  • Enhancements:

    • Initial Temp of vials can now be set independently (used to be defined by operating condition)

    • Fixing a minor bug where freezing point depression was not considered

    • Implementation of second numerical approach to compute the initial amount of ice formed upon nucleation

    • Allow for cooling rate of 0

    • Additional warnings if holding and cooling times exceed the total time

    • Vial group ‘center’ is going to be deprecated in favor of ‘core’ (also: new type ‘side’ was added for 3D)

    • Other, minor bug fixes

Version 1.0

  • Implementation of freezing model for the freezing stage in freeze-drying of a batch of vials on a shelf in python

  • Currently supported features:

    • Simulation of the freezing process, i.e. of thermal evolution and of ice formation, for a batch with arbitrary number of vials

    • Arbitrary cooling protocols (i.e., user may choose cooling rate, integrate holding steps and controlled nucleation)

    • Tracking of nucleation times, nucleation temperatures and solidification times for all vials

    • Stochastic nucleation in the form of a Monte Carlo approach as well as controlled nucleation in the form of forced initiation of nucleation at a certain point

    • Cubic geometry of vial and rectangular arrangement on the shelf