THEORETICAL SUBSTANTIATION OF DYNAMICS OF GRAIN DRYING IN CONTACT METHOD OF HEAT SUPPLY
The basis of the theory of thermal effects on grain with contact method of supplying heat are the patterns of transmission of heat from the heating surface to the treated grain, rationale for the transfer of heat and moisture in the grain particle, and particularities of the removal of moisture from the grain surface. The purpose of the present theoretical research - disclosure of relationships between temperature conditions changing during the drying of grain in contacts type plants. It is revealed that the amount of heat required to heat the grain and remove the moisture in the contact mode of transmission of heat depends on the thermal diffusivity of the material of the heating surface, the temperature difference between the heating surface and processed grains (temperature gradient) and exposure of heat action. The study of the dynamics of grain drying with contact method of supplying heat helped to clarify the physical nature of the phenomena that govern the process of heat treatment of grain. It is proved that with the contact drying in the grain layer the vaporization occurs, caused by negative internal sources of heat and vapor transfer processed through the grain layer to the surface. It is proved that the temperature in the layer of grain depends on various quantities characterizing the heat-drying mode. Analytically obtained expressions for the temperature distribution in the two complementary fields in the contact drying of a thin layer of grain material in the first period allow to analyze and to compare the calculation results with the data obtained experimentally. The dependences can be used to calculate the temperature field within a thin layer of the grain material in the contact drying process in the first period, and for calculating other indicators of process heat.