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Nests and chamber wall temperature control as tools in pharmaceutical freeze-drying. evaluation of heat transfer, edge-vial-effect and drying kinetics
Nests and chamber wall temperature control as tools in pharmaceutical freeze-drying. evaluation of heat transfer, edge-vial-effect and drying kinetics
The scope of this study is to I) investigate the heat transfer and the drying behavior of product vials placed in rack systems as compared to the standard bulk setup and II) analyze the impact of the freeze dryer chamber wall temperature on drying kinetics. As elimination of the chamber wall radiation does not completely reduce the edge vial effect, we hypothesized that neighboring vial affect each other substantially which contributes to the edge-vial effect. Since corner and edge vials have less neighbors than center vials, the cold neighbor vial configuration may significantly impact the product temperature. The drying behavior of a vial surrounded by nothing, empty vials or heat-conductive paste containing vials was studied. Additionally, Kv values of vials standing at varying distance from 1 to 100 mm to each other were determined. To further evaluate the cooling effect of a vial, the number of direct neighbors was varied from 0 to 6.
lyophilization, freeze drying, rack system, heat transfer, edge-vial-effect, radiation cage
Ehlers, Sarah
2020
English
Universitätsbibliothek der Ludwig-Maximilians-Universität München
Ehlers, Sarah (2020): Nests and chamber wall temperature control as tools in pharmaceutical freeze-drying: evaluation of heat transfer, edge-vial-effect and drying kinetics. Dissertation, LMU München: Faculty of Chemistry and Pharmacy
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Abstract

The scope of this study is to I) investigate the heat transfer and the drying behavior of product vials placed in rack systems as compared to the standard bulk setup and II) analyze the impact of the freeze dryer chamber wall temperature on drying kinetics. As elimination of the chamber wall radiation does not completely reduce the edge vial effect, we hypothesized that neighboring vial affect each other substantially which contributes to the edge-vial effect. Since corner and edge vials have less neighbors than center vials, the cold neighbor vial configuration may significantly impact the product temperature. The drying behavior of a vial surrounded by nothing, empty vials or heat-conductive paste containing vials was studied. Additionally, Kv values of vials standing at varying distance from 1 to 100 mm to each other were determined. To further evaluate the cooling effect of a vial, the number of direct neighbors was varied from 0 to 6.