The dependence of the overall drying time and product quality of a lyophilization process on the relative position of vials on a tray with tray sides and without tray sides for different heat input control policies
Keywords and Phrases
Freeze drying in vials; Lyophilization in vials; Square arrays of vials; Hexagonal arrays of vials; Surface geometry of moving interface; Velocity of moving interface; Heating policies; Drying times; Distribution of temperature; Distribution of concentration of bound water
"The dynamic behavior of the primary and secondary drying stages of the lyophilization process were studied when (a) single vials located at different positions on the tray were individually being dried, and (b) the vials on the tray are arranged in clusters of square and hexagonal arrays and all the vials on the tray are simultaneously being dried. For both cases (a) and (b), fast drying times and relatively more uniform distributions of temperature and concentration of bound water at the end of the secondary drying stage are obtained by heat input control that runs the lyophilization process close to the melting and scorch temperature constraints. The arrangement of vials in clusters of hexagonal arrays in case (b) has been found to increase freeze-drying productivity and results in a more desirable distribution of the concentration of bound water at the end of the lyophilization process.
The removal of the tray side, when the vials are simultaneously being dried and heat input control runs the lyophilization process at the temperature constraints, provides the most significant reduction in the overall drying time, consistent with the finding in this work that the total drying time decreases as the height of the tray side decreases. Furthermore, with the removal of the tray side, one obtains more highly uniform water loss among different vials at different locations on the tray, when the drying chamber wall temperature is kept near the melting temperature constraint during primary drying and close to the scorch temperature constraint during secondary drying. Finally, when heat input control runs the lyophilization process at the temperature constraints, .the effect of the drying wall temperature on the overall drying time is not significant"--Abstract, page iv.
Liapis, Athanasios I.
Wang, Jee C.
Chemical and Biochemical Engineering
M.S. in Chemical Engineering
University of Missouri--Rolla
Journal article titles appearing in thesis/dissertation
- Heating policies during the primary and secondary drying stages of the lyophilization process in vials: Effects of the arrangement of vials in clusters of square and hexagonal arrays on trays
xiii, 302 pages, 1 CD-ROM (4 3/4 in.)
© 2004 Kian Hui Gan, All rights reserved.
Thesis - Restricted Access
Library of Congress Subject Headings
Freeze-drying -- Research
Freeze-drying -- Mathematical models
Drying -- Mathematical models
Interfaces (Physical sciences) -- Mathematical models
Print OCLC #
Electronic OCLC #
Link to Catalog RecordElectronic access to the full-text of this document is restricted to Missouri S&T users. Otherwise, request this publication directly from Missouri S&T Library or contact your local library. http://laurel.lso.missouri.edu/record=b5137564~S5
Gan, Kian Hui, "The dependence of the overall drying time and product quality of a lyophilization process on the relative position of vials on a tray with tray sides and without tray sides for different heat input control policies" (2004). Masters Theses. 2534.