Mass conductivity of dispersed and sheet materials under thermodynamic equilibrium conditions

Abstract

The intensification of drying of wet capillary-porous bodies and their structural and deformation transformations is determined by the internal mechanism of moisture transfer in the material being dried. The scientific papers of A.V. Lykova, S.P. Rudobashty, B.S. Sazhina, E.N. Ochneva, N.V. Churaeva are devoted to the study of mass conductivity of various bodies. They confirm the importance to determine the characteristics of internal moisture transfer in the form of liquid and vapor to calculate the intensity of moisture exchange between the surface of a wet material and the coolant and to establish the ratio of moisture and heat flows not only during the drying process, but also during storage of materials. For dispersed and sheet capillary-porous materials of different composition and porous structure, determining the intensity of internal moisture transfer during their interaction with the environment is a relevant area of the research. It determines the drying method, thermal treatment conditions and energy efficiency. Dispersed and sheet capillary-porous materials of various shapes, sizes, structures, and humidity have been used as the objects of the study. To determine the mass conductivity parameters of a wet body during its interaction with a coolant, a thermodynamic method is used. It is based on the use of experimental desorption isotherms and calculated parameters characterizing the porous structure of the material. The authors have applied the method to calculate the mass conductivity coefficients of dispersed and sheet materials based on experimental data obtained under conditions of thermodynamic equilibrium of a wet body and gas. Calculated curves of the dependence of effective mass conductivity coefficients and the moisture content of the dried material are obtained considering environmental parameters. The data obtained on the patterns and the changes in mass conductivity coefficients makes it possible to establish the types of relationships between moisture and the material with the mechanisms of its transfer for a number of dispersed and sheet bodies. The data obtained can be used for the kinetic calculation of the drying process and to determine the conditions of their storage, as well as to identify the conditions for increasing the energy efficiency of dryers with convective supply.