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Advances in Materials Science and Engineering
Volume 2014, Article ID 515180, 7 pages
Research Article

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

Department of Energy and Refrigerating Air-Conditioning Engineering, National Taipei University of Technology, Taipei City 10608, Taiwan

Received 10 September 2013; Revised 8 February 2014; Accepted 25 February 2014; Published 14 May 2014

Academic Editor: Ching-Song Jwo

Copyright © 2014 Hong-Ping Cheng et al. 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.


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.