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论文类型：期刊论文

发表时间：2016-01-01

发表刊物：6th Global Chinese Symposium of Chemical Engineering

收录刊物：SCIE、EI、CPCI-S、ISTIC、Scopus

卷号：24

期号：1,SI

页面范围：116-125

ISSN号：1004-9541

关键字：Adsorption; Desorption; Drying time; Mass transfer; Porous material; Sublimation

摘要：Freeze-drying of the initially porous frozen material with pre-built pores from liquid material was found experimentally to save drying time by over 30% with an initial saturation being 0.28 compared with the conventional operation with the initial saturation being 1, using mannitol as the solid material. In order to understand the mass and heat transfer phenomena of this novel process, a two-dimensional mathematical model of coupled mass and heat transfer was derived with reference to the cylindrical coordinate system. Three adsorption-desorption equilibrium relationships between the vapour pressure and saturation value namely, power-law, Redhead's style and Kelvin's style equation, were tested. Kelvin's style in exponential form of adsorption equilibrium relation gave an excellent agreement between the model prediction and experimental measurement when the equation parameter, gamma, of 5000 was applied. Analyses of temperature and ice saturation profiles show that additional heat needs to be supplied to increase the sample temperature in order to promote the desorption process. Simulation also shows that there is a threshold initial porosity after which the drying time decreased with the increase in the initial porosity. Enhanced freeze-drying is expected to be achieved by simultaneously enhancing mass and heat transfer of the process. (C) 2015 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.