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A Multiphase Porous Medium Transport Model with Distributed Sublimation Front to Simulate Vacuum Freeze Drying

A. Warning[1], J. M. R. Arquiza[1], A. K. Datta[1]
[1]Cornell University, Ithaca, NY, USA

A continuum, porous medium formulation with non-equilibrium sublimation was developed and validated for freeze drying without and with uniform microwave volumetric heating. The model incorporates the effect of Knudsen flow at low pressure and low permeability freeze drying. The distributed, non-equilibrium sublimation demonstrated that the sublimation front is a sharp boundary for high ice saturations but gradually becomes more distributed as ice saturation decreases. Therefore, models assuming a sharp boundary would be equally as effective at higher ice saturations but, at lower ice saturations, a distributed front approach should be used because the front is no longer localized at one point.