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Mathematical Problems in Engineering
Volume 2012, Article ID 921254, 10 pages
Research Article

Distribution of Vapor Pressure in the Vacuum Freeze-Drying Equipment

1School of Mechanical Engineering and Automation, Northeastern University, Shenyang 110004, China
2Normal School of Shenyang University, Shenyang 110015, China

Received 13 April 2012; Accepted 14 May 2012

Academic Editor: Zhijun Zhang

Copyright © 2012 Shiwei Zhang and Jun Liu. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


In the big vacuum freeze-drying equipment, the drying rate of materials is uneven at different positions. This phenomenon can be explained by the uneven distribution of vapor pressure in chamber during the freeze-drying process. In this paper, a mathematical model is developed to describe the vapor flow in the passageways either between material plates and in the channel between plate groups. The distribution of vapor pressure along flow passageway is given. Two characteristic factors of passageways are defined to express the effects of structural and process parameters on vapor pressure distribution. The affecting factors and their actions are quantitatively discussed in detail. Two examples are calculated and analyzed. The analysis method and the conclusions are useful to estimate the difference of material drying rate at different parts in equipment and to direct the choice of structural and process parameters.