摘要:

The present study deals with the fundamentals of the contact-sorption mass transfer theory. The criteria used to determhe the rate of a process and the quality indic- es of a product with contact-sorption dehydration of the material are formulated. The methods to calculate a re-quired amount of sorbent are presented, and an estimate of comparative moisture capacity of sorbents is proposed. Examples of the implementation of sorbents in sublimation and vacuum drying, in fluidized bed drying, and in spray- drying are illustrated.

ISSN:0737-3937    

DOI:10.1080/07373938808916358

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Drying of agricultural grains by and large takes place in the diffusion controlled falling rate period. Therefore, an understanding of the phenomenon of moisture transfer within an individual particles of material is desirable and should be represented precisely by a mathematical model. This paper describes a numerical solution that has been developed for solving spherical diffusion equation describing moisture movement within a grain kernel for accurately calculating bulk drying rate.

ISSN:0737-3937    

DOI:10.1080/07373938808916359

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

As one of the basic steps of the R&D on hybrid drying by combined radiative and convective heating, drying experiments of a stagnant horizontal wet granular layer heated simultaneously by infrared lamps and hot air were conducted throughout a whole period of the drying. An opaque model, in which the incident radiation is assumed to be absorbed only on the surface of the layer, was introduced to explain experimental trends. Then, the effects of combined heating on drying characteristics of three kinds of samples, a silica sand, a brick and a brown coal were discussed by comparing the experimental data with the calculated results.

ISSN:0737-3937    

DOI:10.1080/07373938808916360

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Exact analytical solutions of vacuum-sublimation in an initially partially filled, frozen, porous medium are developed by the similarity variable technique. The sublimation interface temperature, pressure and vapor concentration are obtained in addition to the position of the sublimation interface. Two theoretical models corresponding to the two-region model which allows for vapor transfer in both the frozen region and dried region and the one-region model accounting for vapor transfer in the dried region only are considered. The comparison between these two models and the effect of mass convection into the frozen region are studied. The results show the significant discrepancies in the interface positions predicted by these two models for some values of the important parameters.

ISSN:0737-3937    

DOI:10.1080/07373938808916361

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Experimental drying rates during high temperature drying of Yellow Poplar is analyzed to determine types of drying mechanism. Drying rate during the constant rate period and effective diffusivity during the falling rate periods were obtained at dryer temperatures ranging from 100°C to 150°C.

ISSN:0737-3937    

DOI:10.1080/07373938808916362

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Both theoretical and experimental drying indicate that it is necessary to know the kinetics of drying of various materials. It has been generally accepted that in the first period of drying the process is analogous to evaporation from a free liquid surface, and thusthe drying agent parameters have a significant influence. There is, however, lack of a uniform opinion on the mechanism of drying in the falling drying rate period, although many studies have been devoted to these problems. Since it appeared to be very difficult tosolve analytically the differential equations of the transport phenomena, an attempt is made a t developing approximate methods for a mathematical description of the drying kinetics. The paper presents a new mathematical method of convection drying in the falling drying rate period. Applying the principles of variational calculus, the generalized equations of the temperature and drying curves for the falling drying rate period are obtained.

ISSN:0737-3937    

DOI:10.1080/07373938808916363

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0737-3937    

DOI:10.1080/07373938808916364

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor