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Mathematical Problems in Engineering
Volume 2013 (2013), Article ID 120736, 8 pages
Research Article

Cortex Effect on Vacuum Drying Process of Porous Medium

1School of Mechanical Engineering and Automation, Northeastern University, Shenyang 110004, China
2Shenyang Aircraft Design and Research Institute, Shenyang 110035, China

Received 25 February 2013; Accepted 5 April 2013

Academic Editor: Jun Liu

Copyright © 2013 Zhijun Zhang 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.


Corns, fruits, and vegetables are usually used as porous medium in drying process. But in fact, it must be considered as the cortex effect on mass transfer because the mass transfer of cortex is very difficult than inner medium. Based on the theory of heat and mass transfer, a coupled model for the porous medium vacuum drying process with cortex effect is constructed. The model is implemented and solved using COMSOL software. The water evaporation rate is determined using a nonequilibrium method with the rate constant parameter that has been studied. The effects of different vapor pressures (1000, 5000, and 9000 Pa), initial moisture contents (0.3, 0.4, and 0.5 water saturation), drying temperatures (323, 333, and 343 K), and intrinsic permeability for cortex part (10−13, 10−14, 10−15 m2) on vacuum drying process were studied. The results facilitate a better understanding of the porous medium vacuum drying process that nearer to the reality.