Using mathematical modeling to optimize secondary drying stage of lyophilization technology

2020 ◽  
pp. 33-42
Author(s):  
Konstantin Alekseyev ◽  
Evgeniya Blynskaya ◽  
Sergey Tishkov
Keyword(s):  
Mathematical Modeling ◽  
Heat Transfer ◽  
Mathematical Model ◽  
Freeze Drying ◽  
Design Space ◽  
Heat Transfer Fluid ◽  
Drying Process ◽  
Residual Moisture ◽  
Secondary Drying ◽  
Temperature And Pressure

During lyophilization frozen water and moisture associated with dissolved substances are removed, desorption occurs in the process of secondary drying. This stage is one of the main stages of the technological process in terms of duration comparable with primary freeze drying and is of paramount importance for the further storage of lyophilisates. Mathematical modeling of secondary drying and the use of these methods in calculating design space of the process are described in the presented article. The equations for calculating the rate of secondary drying, residual moisture, and other conditions on the basis of values of the temperature of the heat-transfer fluid and pressure in the freezedrying chamber are shown. Possibilities for determining design space boundaries on the basis of the composition of lyophilisate, required values of residual moisture and drying kinetics are demonstrated. The proposed mathematical model makes it possible to estimate the duration of the secondary drying process for various values of temperature and pressure in the chamber within the design space.

scholarly journals Mathematical model of vacuum freeze-drying in the secondary drying

2007 ◽  
Vol 3 (2) ◽  
pp. 192-196
Author(s):  
Hua Li ◽  
Lihua Li ◽  
Xingli Jiao ◽  
Xueli Qin
Keyword(s):  
Mathematical Model ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Transfer Process ◽  
Present Status ◽  
Freeze Drying ◽  
Mass Transfer Process ◽  
Drying Process ◽  
Secondary Drying ◽  
At Home

The freeze-drying process is a complex heat and mass transfer process virtually. The drying process of freeze-drying is not only the key stage which decides the success of freeze-drying, but also the most difficult stage to control. There are lots of papers about heat and mass transfer in vacuum freeze drying at home and abroad. The present status of research on heat and mass transfer during vacuum freeze drying in the secondary drying is summed up and analyzed, and the trend of research in this field is discussed in this paper.

scholarly journals Freeze-drying microscopy in mathematical modeling of a biomaterial freeze-drying

2012 ◽  
Vol 48 (2) ◽  
pp. 203-209 ◽  
Author(s):  
Camila Figueiredo Borgognoni ◽  
Joyce da Silva Bevilacqua ◽  
Ronaldo Nogueira de Moraes Pitombo
Keyword(s):  
Mathematical Modeling ◽  
Freeze Drying ◽  
Drying Process ◽  
Critical Temperatures ◽  
Fundamental Properties ◽  
Moving Interface ◽  
Energy Consuming ◽  
Sublimation Rates ◽  
Time And Energy

Transplantation brings hope for many patients. A multidisciplinary approach on this field aims at creating biologically functional tissues to be used as implants and prostheses. The freeze-drying process allows the fundamental properties of these materials to be preserved, making future manipulation and storage easier. Optimizing a freeze-drying cycle is of great importance since it aims at reducing process costs while increasing product quality of this time-and-energy-consuming process. Mathematical modeling comes as a tool to help a better understanding of the process variables behavior and consequently it helps optimization studies. Freeze-drying microscopy is a technique usually applied to determine critical temperatures of liquid formulations. It has been used in this work to determine the sublimation rates of a biological tissue freeze-drying. The sublimation rates were measured from the speed of the moving interface between the dried and the frozen layer under 21.33, 42.66 and 63.99 Pa. The studied variables were used in a theoretical model to simulate various temperature profiles of the freeze-drying process. Good agreement between the experimental and the simulated results was found.

Understanding and optimization of the secondary drying step of a freeze-drying process: a case study

2020 ◽  
pp. 1-15 ◽  
Author(s):  
Getachew Assegehegn ◽  
Edmundo Brito-de la Fuente ◽  
José M. Franco ◽  
Críspulo Gallegos
Keyword(s):  
Freeze Drying ◽  
Drying Process ◽  
Secondary Drying

scholarly journals Analysis of Heat Transfer Mechanism for Shelf Vacuum Freeze-Drying Equipment

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Hong-Ping Cheng ◽  
Shian-Min Tsai ◽  
Chin-Chi Cheng
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Low Temperature ◽  
Temperature Gradient ◽  
Freeze Drying ◽  
Heat Transfer Fluid ◽  
Processing Temperature ◽  
Fluid Temperature ◽  
Three Dimension ◽  
Flow Rates

Vacuum freeze-drying technology is applicable to the process of high heat-sensitive products. Due to the long drying period and extremely low processing temperature and pressure, the uniform and efficiency of heat transfer fluid temperature in shelf are critical for product quality. Therefore, in this study, the commercial computer fluid dynamics (CFD) software, FLUENT, was utilized for three-dimension numerical simulation of the shelf vacuum freeze-drying process. The influences of different inlet and outlet positions for shelves on the uniformity of the flow rate and temperature were discussed. Moreover, it explored the impacts on the temperature gradient of shelves after heat exchange of different flow rates and low temperature materials. In order to reduce the developing time and optimize the design, the various secondary refrigerants in different plies of shelves were investigated. According to the effect of heat exchange between different flow rates and low temperature layer material shelves on the temperature gradient of shelves surface, the minimum temperature gradient was 20 L/min, and the maximum was 2.5 L/min.

scholarly journals Effect of the Freeze-Drying Process on the Physicochemical and Microbiological Properties of Mexican Kefir Grains

Processes ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 127 ◽  
Author(s):  
Alicia Conde-Islas ◽  
Maribel Jiménez-Fernández ◽  
Denis Cantú-Lozano ◽  
Galo Urrea-García ◽  
Guadalupe Luna-Solano
Keyword(s):  
Moisture Content ◽  
Water Activity ◽  
Freeze Drying ◽  
Survival Rates ◽  
Freezing Temperature ◽  
Freezing Time ◽  
Residual Moisture Content ◽  
Drying Process ◽  
Residual Moisture ◽  
Kefir Grains

The purpose of this study was to investigate how the properties of Mexican kefir grains (MKG) are affected by the operating parameters used in the freeze-drying process. The factors investigated were the freezing time (3–9 h), freezing temperature (−20 to −80 °C), pressure (0.2–0.8 mbar), and lyophilization time (5–20 h). The maximum range of change and one-way analysis of variance showed that lyophilization time and freezing time significant affects (p < 0.05) the response variables, residual moisture content and water activity, and pressure had a significant effect on the color difference and survival rate of probiotic microorganisms. The best drying conditions were a freezing time of 3 h, a freezing temperature of −20 °C, a pressure of 0.6 mbar, and a lyophilization time of 15 h. Under these conditions, we obtained a product with residual moisture content below 6%, water activity below 0.2, and survival rates above 8.5 log cfu per gram of lactic acid bacteria and above 8.6 log for yeast.

scholarly journals The Freeze-Drying of Foods—The Characteristic of the Process Course and the Effect of Its Parameters on the Physical Properties of Food Materials

Foods ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1488 ◽  
Author(s):  
Dorota Nowak ◽  
Ewa Jakubczyk
Keyword(s):  
Mechanical Properties ◽  
Physical Properties ◽  
Structural Properties ◽  
Freeze Drying ◽  
Process Conditions ◽  
Drying Process ◽  
High Quality ◽  
Freeze Dried ◽  
Secondary Drying ◽  
Selection Of

Freeze-drying, also known as lyophilization, is a process in which water in the form of ice under low pressure is removed from a material by sublimation. This process has found many applications for the production of high quality food and pharmaceuticals. The main steps of the freeze-drying process, such as the freezing of the product and primary and secondary drying, are described in this paper. The problems and mechanisms of each step of the freeze-drying process are also analyzed. The methods necessary for the selection of the primary and secondary end processes are characterized. The review contains a description of the effects of process conditions and the selected physical properties of freeze-dried materials, such as structural properties (shrinkage and density porosity), color, and texture. The study shows that little attention is given to the mechanical properties and texture of freeze-dried materials obtained from different conditions of the lyophilization process.

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