Use of manometric temperature measurement (MTM) and SMART™ freeze dryer technology for development of an optimized freeze‐drying cycle

2007 ◽  
Vol 96 (12) ◽  
pp. 3402-3418 ◽  
Author(s):  
Henning Gieseler ◽  
Tony Kramer ◽  
Michael J. Pikal
Keyword(s):  
Temperature Measurement ◽  
Freeze Drying ◽  
Manometric Temperature Measurement ◽  
Freeze Dryer

scholarly journals Cycle Development in a Mini-Freeze Dryer: Evaluation of Manometric Temperature Measurement in Small-Scale Equipment

2021 ◽  
Vol 22 (4) ◽  
Author(s):  
Tim Wenzel ◽  
Margit Gieseler ◽  
Ahmad M. Abdul-Fattah ◽  
Henning Gieseler
Keyword(s):  
Temperature Measurement ◽  
Temperature Control ◽  
Process Parameters ◽  
Wall Temperature ◽  
Freeze Drying ◽  
Small Scale ◽  
Residual Moisture ◽  
Product Temperature ◽  
Manometric Temperature Measurement ◽  
Freeze Dryer

AbstractThe objective of this research was to assess the applicability of manometric temperature measurement (MTM) and SMART™ for cycle development and monitoring of critical product and process parameters in a mini-freeze dryer using a small set of seven vials. Freeze drying cycles were developed using SMART™ which automatically defines and adapts process parameters based on input data and MTM feedback information. The freeze drying behavior and product characteristics of an amorphous model system were studied at varying wall temperature control settings of the cylindrical wall surrounding the shelf in the mini-freeze dryer. Calculated product temperature profiles were similar for all different wall temperature settings during the MTM-SMART™ runs and in good agreement with the temperatures measured by thermocouples. Product resistance profiles showed uniformity in all of the runs conducted in the mini-freeze dryer, but absolute values were slightly lower compared to values determined by MTM in a LyoStar™ pilot-scale freeze dryer. The resulting cakes exhibited comparable residual moisture content and optical appearance to the products obtained in the larger freeze dryer. An increase in intra-vial heterogeneity was found for the pore morphology in the cycle with deactivated wall temperature control in the mini-freeze dryer. SMART™ cycle design and product attributes were reproducible and a minimum load of seven 10R vials was identified for more accurate MTM values. MTM-SMART™ runs suggested, that in case of the wall temperature following the product temperature of the center vial, product temperatures differ only slightly from those in the LyoStar™ freeze dryer.

Simulations and Measurements of Water Vapor Flow and Ice Dynamics in a Freeze-Dryer Condenser

2011 ◽  
Author(s):  
Arnab Ganguly ◽  
Alina Alexeenko ◽  
Frank DeMarco
Keyword(s):  
Water Vapor ◽  
Low Temperature ◽  
Mass Flux ◽  
Freeze Drying ◽  
Laboratory Scale ◽  
Vapor Flow ◽  
Ice Accretion ◽  
Production Scale ◽  
Ice Dynamics ◽  
Freeze Dryer

Freeze-drying is a low-pressure, low-temperature condensation pumping process widely used in the manufacture of pharmaceuticals for removal of solvents by sublimation. The performance of a freeze-dryer condenser is largely dependent on the vapor and ice dynamics in the low-pressure environment. The main objective of this work is to develop a modeling and computational framework for analysis of vapor flow and ice dynamics in such freeze-dryer condensers. The direct Simulation Monte Carlo (DSMC) technique is applied to model the relevant physical processes that accompany the vapor flow in the condenser chamber. Low-temperature water vapor and nitrogen molecular model is applied in the DSMC solver SMILE to simulate the bulk vapor transport. The developing ice front on the coils of the condenser is tracked based on the steady state mass flux computed at the nodes of the DSMC surface mesh. Verification of ice accretion simulations has been done by comparison with the solution for analytical free-molecular flow over a circular cylinder. The developed model has also been validated with measurements of ice growth in a laboratory and production scale freeze-dryer using time-lapse imaging. To illustrate the application of the ice accretion algorithm in the area of bio-pharmaceutical freeze-drying, the current work discusses the effect of the condenser geometry and non-condensable gas on non-uniformity of mass flux in a laboratory scale and production scale freeze-dryer condenser. In addition, the simulations are used to predict the ice formation on the coils of the condenser. It was found that in the laboratory scale dryer, the presence of a duct connecting the product chamber and condenser increased non-uniformity by 65% at a sublimation rate of 5 g/hr. The measured ice thickness on the coils of the condenser was found to increase non-linearly. This non-linearity was captured within an accuracy of 1% compared to the measurements towards the end of a 24 hour cycle using an unsteady icing model while that using a steady model was within 14%. In the production dryer, while the steady model predicted the iced coil diameter within an accuracy of 2–5% with respect to the measurements, the unsteady model captured this within an accuracy of 1–6%. The DSMC simulations demonstrate that by augmenting its capabilities with the icing model, it is possible to predict the performance of a freeze-dryer condenser with any arbitrary design.

scholarly journals The Effect of the Drying Method on the Quality of Dried Kiwi Slices

2017 ◽  
Vol 2 (1) ◽  
pp. 1 ◽  
Author(s):  
Kamyar Movagharnejad ◽  
Sepideh Pouya
Keyword(s):  
Antioxidant Activity ◽  
Ascorbic Acid ◽  
Acid Content ◽  
Freeze Drying ◽  
Color Change ◽  
Ascorbic Acid Content ◽  
Standard Methods ◽  
Freeze Dryer ◽  
Microwave Dryer

Abstract— Drying is known as a food preservation method which increases the food’s storage time by water reduction. Traditional drying consisted of open sun-drying, but different industrial dryers have been widely used in recent times. The new dryers consist of convective, infrared, ultrasound, freeze fluidized bed and freeze dryers. All of these dryers reduce the water content but under different mechanisms which leads to the end products with different qualities. In this study we aim to compare the difference in quality of kiwi fruit slices dried by three different dryers: 1. Convective tray dryer, 2. Microwave dryer and 3. Freeze dryer. The tray dryer experiments were conducted in two air temperatures of 60 and 80oC in the constant air velocity of 0.8 m/s. The microwave dryer operated in 3 output powers of 180, 270 and 360 W. The condenser temperature and pressure in the freeze dryer reduced to -50oC and 0.1 mbar, respectively. The operating conditions and time were regulated so that the moisture content of all dried samples reduced to nearly 10% in the wet basis. The three parameters of color change, ascorbic acid and antioxidant reduction were selected as the measuring criteria for the comparison of the product qualities. The experiments show that the freeze drying caused the minimum color change while the microwave drying in the maximum power of 360W caused the maximum amount of color change. The concentration of ascorbic acid was measured in the fresh fruits and dried samples by standard methods. The measurements proved that the ascorbic acid content of the freeze dried samples was 80% of the fresh fruits. The ascorbic acid content of other samples was much lower. The antioxidant activity of the dried samples and the fresh fruits was also measured by standard methods and the experimental data also showed that the freeze drying causes the minimum reduction in the antioxidant activity.

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