HEAT AND MASS TRANSFER IN THE DRYING OF A CYLINDRICAL BODY IN AN OSCILLATING MAGNETIC FIELD

A problem on the heating of a cylindrical body of infi nite length in an oscillating electromagnetic fi eld in the process of its drying has been formulated and solved analytically with account of the intermittence of irradiation of the body defi ned by the Heaviside unit function, the exponential-law absorption of electromagnetic energy by it, and the convective heat and mass exchange between the surface of the body and the environment having constant parameters. The intensity of evaporation of moisture from the surface of the body was determined on the basis of analytical solution of the problem on the mass transfer (moisture diffusion) in it on the assumption that the phase transformations of the body proceed near its surface. Solutions of the problem on the heating of the cylindrical body have been obtained for the cases of nonuniform and uniform distributions of its local temperature, the temperature of the body averaged over its volume, and the temperature gradient near the surface of the body. The "serviceability" of these solutions was verifi ed on the basis of numerical simulation, with them, of the drying of a seed shaped as a cylinder under the action of an oscillating infrared radiation. As a result of the numerical simulation performed, a technological regime of drying of seeds at minimum and maximum temperatures of their heating by on oscillating infrared radiation for a defi nite period of time in a cycle, providing not only the drying of the seeds but also substantial improvement of their sowing properties (the sprouting energy and the germination power), has been found. It is shown that the oscillating infrared heating of seeds can be used for their drying in pseudofl uidized and vibrofl uidized beds.
   
Author:  S. P. Rudobashta, G. A. Zueva, and É. M. Kartashov
Keywords:  electromagnetic heating, drying, convective heat and mass transfer, intermittent irradiation, thermolabile materials
Page:  227