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An analysis of the lyophilization process using a sorption‐sublimation model and various operational policies
Author(s) -
Millman M. J.,
Liapis A. I.,
Marchello J. M.
Publication year - 1985
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690311003
Subject(s) - sublimation (psychology) , sorption , freeze drying , phase change , process engineering , chemistry , chemical engineering , environmental science , chromatography , thermodynamics , adsorption , engineering , organic chemistry , physics , psychology , psychotherapist
The freeze‐drying process is studied under various operational policies through the use of a sorption‐sublimation model. The operational policy that provides the shortest drying times keeps the pressure at its lowest value. The upper and lower heating plates are independently controlled so that the material constraints are encountered and held throughout the free water removal phase. Under certain conditions, and for the case of samples of small thickness, the sorbed water profiles may have segments whose bound water concentrations are higher than those at the start of the free water removal phase. It is shown that the criterion used in terminating the freeze‐drying process is of extreme importance, since it may lead to an undesirable sorbed water profile which may deteriorate the quality of the dried product.