The goal of the work is to enhance the efficiency of the process of preparing complete feed pellets by simultaneously disinfecting them through the improvement of the expander's design and justification of its structural and technological parameters.
The object of research is the technological process of preparing full-rational expanded compound feed and the technical means for its implementation.
The subject of research is the regularity of the process of expansion of complete ration compound feed.
Research methods. Theoretical studies involve the examination of the interaction patterns between the working elements of the feed expander with the technological material using methods of systemic analysis, theoretical mechanics, mechanics of continuous media, integral and differential calculations, numerical modeling in the Simcenter Star-CCM+ software package. Experimental research involved the use of standard and developed techniques, employing created physical models and experimental samples of working elements, instruments, and equipment. Experimental studies were conducted in both laboratory and production conditions and included the methodology of planning multifactor experiments. The analysis of experimental data was carried out using statistical data processing methods and the Wolfram Cloud applied software.
Scientific novelty of the obtained results. A physical-mathematical model of the process of forming expandates from feed has been developed, connecting the technological parameters of the expanding process (moisture and temperature) with the physico-mechanical properties of the feed mixture (average particle diameter of the mixture, Young's modulus, Poisson's ratio, cohesion work per unit area). Analytical and experimental dependencies in the form of second-order regression equations for the productivity of the expander, its power consumption, specific energy consumption of the expanding process, and the density of the obtained expandates have been obtained. These dependencies are related to the radii of the narrowing cylinder and the concave cone of the forming attachment, the distance between them, the screw rotation frequency, and the moisture content of the feed.
Further development of the physical-mathematical apparatus of the movement of solid feed components, treated as discrete elements based on the spring-damper contact model of Hertz-Mindlin, in the screw channel of the expander has been achieved. This forms the basis for the numerical modeling methodology of the feed expanding process using the Simcenter STAR-CCM+ software package.
Practical significance of the obtained results. The developed press matrix with justified rational design and technological parameters within the composition of the OEE 30.2 feed expander (Amandus Kahl GmbH & Co. KG) has been implemented in the production of LLC NVO "Hlobynskyi Svynokomplex". The results of the scientific and technical work, in the form of design and technical documentation for the improved feed expander, have been implemented and utilized in the production of LLC VO "Voskhod" to manufacture a corresponding experimental sample. The developed physical-mathematical models and numerical modeling methodologies have been introduced into the educational components of the Educational and Scientific Institute "Agroengineering" for students of the first (bachelor's) and second (master's) levels of higher education at DDAEU.
Justification of the design and technological scheme of the feed expander with an improved forming attachment, which differs in that it consists of a narrowed cylinder area, a concave cone, and a crown nut, has been provided. When the heated plasticized mass moves towards the narrowed area of the forming attachment, there is an increase in pressure, followed by a sharp decrease after passing through it. This is achieved by increasing the working area's volume through the shape of the concave cone. As a result, the plasticized mass expands and exits through the crown nut of the forming attachment, forming expandates.
To assess the correctness of the chosen models and the physical-mathematical apparatus, numerical modeling of the compression process of feed components in a cylindrical vessel under the action of a piston was conducted in STAR-CCM+. The study of the compression process of feed components was conducted for various physico-mechanical properties, including the average particle diameter of the mixture, Young's modulus, Poisson's ratio, and cohesion work per unit area at three fixation levels. Numerical modeling resulted in hysteresis laws for the elastic components of the feed, and regression equations were obtained for the loop area change of the hysteresis and the coefficient of mechanical losses, as well as the height of the obtained expandate concerning the average particle diameter of the mixture, Young's modulus, Poisson's ratio, and cohesion work per unit area.
