INVESTIGATION OF THE DIFFUSION PROPERTIES OF PLANT CAPILLARY-POROUS COLLOIDAL MATERIALS WITH REGARD TO THEIR SHRINKAGE

Based on the zonal method, the temperature and concentration dependences of the moisture diff usion coeffi cient in materials subject to shrinkage in the process of drying (plates cut from apple, carrot, and beet) were found experimentally. The concentration dependences of the moisture diff usion coeffi cient in these materials were determined from drying curves obtained in the absence of external diff usion resistance. Shrinkage of materials was determined experimentally, the temperature dependences of the obtained diff usion coeffi cients were described on the basis of the theory of activated molecular diff usion of moisture in the material. It is shown that the temperature dependence of the moisture diff usion coeffi cient in the indicated materials is described satisfactorily by the Arrhenius equation, on the basis of which, for these materials, formulas were obtained that express the dependence of the coeffi cient of moisture diff usion in them on their moisture content and temperature and that can be used in engineering calculations. The obtained data on the moisture diff usion coeffi cient in the studied materials are compared with similar data obtained for other materials. It is shown that the concentration dependences of the moisture diff usion coeffi cients of materials subject to shrinkage during drying have the same nature and order of magnitude as similar dependences for materials without shrinkage. The drying curves calculated using the obtained formulas were compared with the experimental drying curves, which showed their satisfactory similarity.
   
Author:  S. P. Rudobashta, V. M. Dmitriev
Keywords:  convective drying, diff usion, Arrhenius equation, kinetic calculation
Page:  1357