Authors present the influence of grain substitute diameter, dz, inert material ball diameter, Di, air flow velocity, U, and bed height, S, on the air flow resistance, ∆P, through the layer of inert material mixed with grain. The tests were run on dry rape seed, wheat, corn, and field pea. Porcelain balls of .025 m and .030 m diameter and polypropylene balls of .035 m and .0375 m diameter were used as inert material. The relationship of ∆P vs. Di, U, and S was described by a dimensionless equation.
The model of a ring-shaped drying chamber was used to simulate wheat grain drying with air heated by "funnel" walls of a drum dryer. Moisture transfer between air and the grain surrounding it, has been described by the diaensionlese equation: Shr = С . Xa . Ref . Zg . Sc*h
Changes in lenght, width and thickness of maize grain as well in its section area during drying were determined on experimental stands. Substantial differences in dynamics of changes these dimensions during particular drying phases were proved. Changes in dimensions depending on grain moisture content (dry basis) are described by the equations.
The model of a cylindrical sieve drying chamber was used to simulate wheat grain heating with air heated by funnal walls of a drum dryer. Heat transfer between the wall of funnel and "the grain jacket" surrounding it has been described by the dimensionlese equation: Nu = С . X a . Re t . Z g.
On the experimental equipment it has been investigated the contact heating of wheat grain in the packing of porcelain balls. The heat transfer between the heat balls and grains has been described by the dimensionless equation.