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 diffusion coefficient 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 diffusion coefficient in these materials were determined from drying curves obtained in the absence of external diffusion resistance. Shrinkage of materials was determined experimentally, the temperature dependences of the obtained diffusion coefficients were described on the basis of the theory of activated molecular diffusion of moisture in the material. It is shown that the temperature dependence of the moisture diffusion coefficient 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 coefficient of moisture diffusion in them on their moisture content and temperature and that can be used in engineering calculations. The obtained data on the moisture diffusion coefficient in the studied materials are compared with similar data obtained for other materials. It is shown that the concentration dependences of the moisture diffusion coefficients 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. © 2022, Springer Science+Business Media, LLC, part of Springer Nature.