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Proceedings of Symposium on Energy Engineering in the 21<sup>st</sup> Century (SEE2000) Volume I-IV

ISSN:
1-56700-132-7 (Print)

NON-FICK EFFECT IN ABNORMAL HIGH INTENSE DRYING PROCESS OF WET POROUS MATERIALS

Xin Wang
Department of Power Engineering Southeast University, Nanjing 210096, China

M. H. Shi
Department of Power Engineering, Southeast University, Nanjing, 210096, China

Weiping Yu
Department of Power Engineering Southeast University, Nanjing 210096, China

Abstract

Because mass propagation velocity has a finite value in porous media for an unsteady mass transfer process, the hypothesis that mass propagation velocity in mass transfer process is infinite is far away from practical situation for high intense drying process in wet porous materials. Like heat transfer, a description of an unsteady humidity profile in the form of the hyperbolic equation is advanced. From the equation, wave characteristic can be seen in the mass transfer field of inner material. One-dimensional hyperbolic equation of mass transfer for high intense drying process of wet porous materials has been developed in this paper. The non-Fick phenomena in high intense drying process are analyzed by the comparison of the solutions between the Fick equation and the non-Fick equation. The calculating results show that when mass flux or mass transfer coefficient is high, the non-Fick effect is notable and it is not negligible in an intense drying process.