To the mathematical model of the process of contact heating of seeds in vacuum

Annotation Purpose. To increase the degree of adequacy of the mathematical model of contact heating of seeds in a vacuum due to the refinement of the overall coefficient of thermal conductivity. Methods. The study of the mathematical model of the process of contact heating of seeds in vacuum was carried out using the methods of optical physics, planimetry, thermal physics. Mathematical dependencies were developed using algebraic transformations. The analysis of the obtained mathematical dependencies was carried out by the methods of technical analysis and graphic-analytical methods by comparing the graphs of the seed heating kinetics. Results. The total heat flow in the vacuum chamber, which exits the heating surface and is divided into two flows, has been studied, one of them transfers heat due to heat conduction through the touch of seeds with a heating surface and between themselves, and the second transfers heat through radiation in the cavities between the seeds. Calculation formulas for these heat fluxes have been developed, through which the formula for calculating the total thermal conductivity coefficient has been determined. This formula shows that the overall thermal conductivity is less than the theoretical value and depends on the equivalent seed diameter and seed characteristics. Conclusions. It has been established that the total thermal conductivity coefficient of seeds is less than the theoretical one due to voids between seeds, in which the heat of less heated layers propagates through radiation. The loss of thermal energy in the voids between the seeds increase the duration of the heating process and depend on the equivalent diameter of the seeds, the degree of blackness and the difference between the initial temperatures of the seeds and the heating surface. Keywords: seeds, contact heating, seed temperature, thermal conductivity, radiation, heat flux, heating surface, equivalent diameter, space between seeds.