The article presents the results of experimental studies of the air heating efficiency in heliocollectors with different surface forms developed in order to justify their use in equipment for active ventilation of grain and feed raw materials.
The article examines the study of the separation of grain materials in pneumatic channels with an artificially generated distribution of air velocity in the cross-section channel to determine the rational form and parameters of the material supply and options for grain material separation into fractions. The regularities of the weevil movement were theoretically investigated and established in the form of mathematical models of the dynamics of the movement of a solid particle in airflow, which differ from the known ones by taking into account the action of lateral forces, the concentration of the material, and the use of a power-law and an artificially formed exponential law of air distribution facilitated to increase the differences (splitting) trajectories of caryopses by 20 %. The solution of the system of nonlinear differential equations with initial conditions is performed in the Mathcad software environment in the form of trajectories of the grain in the air flow. It allows calculating their trajectories, which differ in windage coefficients and determine the rational values of the parameters of pneumo-gravity and pneumo-inertia separators. Using the obtained dependencies for the development of air separators contributes to determine the initial speed of entry and the direction of entry of the kernels into the airflow, as well as to determine the trajectories of material movement in the air channels with the bottom unloading of material.
Purpose. Clarification of the mathematical description and calculation of the processes of micronization and vibrational movement of grain in cross-air flow on the basis of experimental studies. Methods. Experimental studies were performed on a manufactured sample of a machine for high-intensity heat treatment of grain using experimental planning methods and statistical processing of experimental data. Results. A mathematical description of the motion of grain mixture particles on a vibroconveyor with high-intensity heat treatment of grain during action on the mixture of air flow is given. The trajectories of particles with different sizes depending on high-intensity heat treatment are obtained. With certain assumptions, the regularities of the change in the speed of movement and exposure of the micronization of the material particle (grain) from the coordinates and humidity are obtained. Conclusions. As a result of research: 1) a regression dependence was obtained to determine the micronization exposure and it was established that the micronization exposure for the given energy parameters of the installation should last from 60 to 180 seconds; 2) the change of the speed of vibratory movement of grain depending on its humidity is theoretically substantiated and it is proved that the ascending air flow increases the speed of grain movement, and the descending one – decreases; 3) experimentally determined the empirical dependence of changes in the speed of vibration, which allows the formation of the required speed of vibration of grain by changing the parameters: the slope of the vibrating surface 5÷8°, oscillation frequency 33÷52 s-1, grain moisture 10÷20% and downward air flow rate 0.1÷2 m / s in rational modes of installation for grain micronization on a vibrating conveyor. Keywords: trajectory, vibration displacement, vibration conveyor, air flow, micronization, humidity, coefficient of friction.
Annotation Purpose. Improving the mathematical description of the motion of the dynamics of grain motion in the horizontal non-uniform air flow of aerodynamic separators. Methods. Theoretical determination of the regularities of the plane motion of the grain in an uneven air flow determines the analytical method of research based on the compilation and analysis of the equations of motion of the grains in the form of a sphere in the air flow of the horizontal pneumatic channel of the separator. The mathematical model is formulated by obtaining differential equations of motion of the components of the grain material, which are represented by a material point and a complex indicator of aerodynamic properties – the coefficient of vitality (sail). Results. The flat motion of the grain in the uneven air flow of the horizontal pneumatic channel of the aerodynamic separator through the sieve surface with cracks in the axial direction of air is absorbed. The obtained equation of grain motion during horizontal air flow allows to determine the dependence of grain velocity in air-grain medium on a number of factors: geometric parameters of the separator, feed angle, initial kinematic mode of the material, and grain vitality coefficient. Conclusions 1. An improved mathematical model of the dynamics of the motion of a solid particle in a horizontal air flow is formulated, which differs from those known in that it reproduces the action of unaccounted factors (non-uniformity of the velocity field, action of lateral forces, material concentration). It is established that the change of the sign of the air flow gradient in the cross section leads to a change in the direction of the trajectories of the light fraction KZM, which increases the completeness of the removal of the feed fraction to 90% and increases the separation of the seed fraction by 15-20%. up to 2-3%. Changing the diagram of the air velocity in the horizontal channel increases the velocity in the wall area, which increases the clarity of the division by 18-24%. 2. The solution of the system of nonlinear differential equations with initial conditions is performed in the MathCad software environment in the form of grain motion trajectories in horizontal air flow, which allows calculating grain motion trajectories differing in vitality coefficients and determining rational values of pneumatic gravity separators. Keywords: variable air velocity, trajectory, lateral force, fractions, horizontal air flow, fractionation process, grain.
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