SIMULATION OF THE PROCESS OF FORMING THE EDGE AND MIXING THE COMPONENTS OF THE COMPOST MIXTURE WITH A SINGLE-DRAMED AERATOR
Authors: Elchyn Aliiev , Pavlenko Sergey 
Published: May 2024

The most widespread approach for implementing the technological process of organic compost production involves using mobile aerator-mixers of the rotary-drum type. Based on the analysis of various designs of mechanized composting equipment from previous theoretical and experimental studies conducted by renowned scientists, as well as our own research, it has been established that mechanized compost production requires further investigation. The analysis revealed that rotary drum-blade working elements are efficient. However, there is insufficient research on the dependencies of changes in the height of the pile during formation, indicators of homogeneity and structure of the mixture, energy consumption during the operation of drum-blade working elements in relation to the rotation frequency, working element's linear velocity, and geometric parameters of the blades. Additionally, changes in the bulk density, mixture structure, and temperature distribution within the pile under the influence of the working elements have not been investigated. This highlights the relevance of conducting research in the chosen direction.

The analysis of developed models for the interaction of the working element with the compost mixture has shown that they cannot be used to assess the quality of mixing and pile formation, as it is necessary to consider the movement of discrete particles that make up the compost mixture. The mathematical description of the movement of discrete elements is achievable using modern CAE (Computer-Aided Engineering) systems, and one such system is Simcenter Star-CCM+.

Through numerical simulation of the technological process of pile formation and mixture mixing, an argumentation of the constructive and technological parameters of the working element of a single-drum aerator was conducted.

To construct the physical-mathematical model of the compost mixing and pile formation processes, the following mesh and physical models were utilized: meshless DEM (Discrete Element Method), solution interpolation, Lagrangian multiphase, unsteady implicit, DEM, multiphase interaction, gravity force, and boundary forces of DEM.

As a result of simulating the compost mixture mixing process using a single-drum blade working element, dependencies of the height (H') and width (L') of the formed pile on the rotation frequency (n), linear velocity of the working element (V), and the blade's inclination angle (ξ) were established. A mathematical expression in the form of second-order regression equations was derived, linking the coefficient of variation of mixing quality (δ) with the research factors. Solving the compromise problem using the Wolfram Cloud software package allowed us to determine the rational parameters for the working element: rotation frequency (n) of 237 rpm, linear velocity (V) of 0.15 m/s, and blade inclination angle (ξ) of 15.8°. Consequently, the coefficient of variation of mixing quality (δ) was found to be 0.51, and the width (L') and height (H') of the formed pile were 1.23 m and 1.54 m, respectively.