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Mathematical Problems in Engineering
Volume 2014 (2014), Article ID 798040, 6 pages
http://dx.doi.org/10.1155/2014/798040
Research Article

Heat and Mass Transfer of Droplet Vacuum Freezing Process Based on Dynamic Mesh

1School of Mechanical Engineering, Shenyang University, Shenyang 110044, China
2School of Mechanical Engineering and Automation, Northeastern University, Shenyang 110004, China

Received 14 June 2014; Accepted 10 July 2014; Published 20 July 2014

Academic Editor: Jun Liu

Copyright © 2014 Lili Zhao 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.

Abstract

A numerical simulation using dynamic mesh method by COMSOL has been developed to model heat and mass transfer during vacuum freezing by evaporation of a single droplet. The initial droplet diameter, initial droplet temperature, and vacuum chamber pressure effect are studied. The surface and center temperature curve was predicted to show the effect. The mass transfer rate and radius displacement were also calculated. The results show the dynamic mesh shows well the freezing process with the radius reduction of droplet. The initial droplet diameter, initial droplet temperature, and vacuum pressure have obvious effect on freezing process. The total freezing time is about 200 s, 300 s, and 400 s for droplet diameter 7.5 mm, 10.5 mm, and 12.5 mm, respectively. The vacuum pressure less than 200 Pa is enough for the less time to freezing the droplet, that is, the key point in freezing time. The initial droplet temperature has obvious effect on freezing but little effect on freezing temperature.