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Passage DEM - Discrete Element Method

Lyophilization (Freeze Drying) Process - PASSAGE®/Freeze Drying Software

Passage/FreezeDrying is a computer program designed for the simulation of freeze drying processes in vials and pans. 

Passage/FreezeDrying provides modeling of containers with axisymmetric boundary conditions with both primary and secondary drying simulation capabilities.  The software also handles containers with asymmetric boundary conditions, as in the case of vials placed in corners or near the walls of freeze-drying ovens. 

The user-friendly, interactive preprocessor accepts externally generated meshes and support automatic entry of material properties, process conditions, and display of geometry.

Passage/FreezeDrying also has user-friendly, interactive post-processing modules which display the computed temperature, vapor concentration, water pressure, and glass transition distributions in the form of contour plots and x-y graphs.  Animation of sublimation front movements can also be obtained easily.

Temperature and pressure distribution after 8 hrs. of primary drying in a vial

primary drying in a vial

Sorbed water concentration in primary drying

concentration in primary drying

Sorbed water concentration in secondary drying

concentration in secondary drying

Some objectives of using CAE is to identify freeze drying  process conditions to:

  • Maximize drying rate and increase production
  • Prevent chemical & structural degradation
  • Provide uniform drying throughout the material
  • Predict drying time for primary and secondary stages to desired levels of water concentration

Some results of the analysis:

  •  Time for primary and secondary drying of products
  •  Location for isolated islands of ice in pan drying
  •  Concentration contours
  •  Absorbed water concentration
  •  Interface position in time
  •  Sublimation frontal movement
  •  Temperature contours and history
  •  Water pressure contours

Some Application Areas

  • Freeze-dried pharmaceutical
  • Freeze-dried food processes
  • Vials and pans


  • Provide a tool to predict drying times and process conditions to alleviate "islands of ice" and glassing of product
  • Results can be used for FDA process approval
  • Minimize cost of testing and shorten drying time to increase yield
  • Provide detailed understanding of primary and secondary drying processes
PASSAGE®/FreezeDrying Software for freeze drying simulation  was developed and is offered exclusively by Technalysis, Inc.
Technalysis' Engineering Services for Pharmaceutical Industry 
Pharmaceutical Industry Brochure (.pdf) 
Article on Simulation Tools for Pharmaceutical Industry by Akin Ecer, President, Technalysis, Inc.

Passage Licensing Options:

Technalysis offers various licensing options and support to fit your needs and budget. Contact us to discuss your needs. E-mail or call 317-291-1985
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