Vol 57, No 4 (2023)

A model was proposed for determining the efficiency of fractional separation in a uniflow cyclone. The model includes parameters that characterize the motion of a particle in the cyclone and, hence, the degree of separation, namely, the distance that the particle travels when moving in a helical path, and this path itself. The separation efficiency in a uniflow cyclone of a new design was experimentally studied. The experiments were carried out with quartz flour of four particle size fractions: 15, 20, 30, and 50 μm. The efficiency of the cyclone in the separation of small particles was high for apparatuses of this type. The separation efficiency curves were analyzed.

A method and a mathematical model were proposed to calculate the chemical and energy engineering process of roasting of phosphate ore raw materials in a moving dense bed on the grate of a traveling-grate roasting machine. The results of computational experiments on the developed computer model were used to analyze the limiting and optimal conditions of drying and roasting of lump and pelletized phosphate ore raw materials on the traveling grate of the roasting machine. The limiting conditions for the calcination of lump and pelletized ore raw materials loaded as a monolayer bed of lumps, for co-roasting, and as a bed of phosphorite pellets were determined taking into account the technological restrictions on the existing traveling-grate roasting machines. For phosphate ore raw materials, it was determined that the maximum achievable degree of decarbonization in high-temperature roasting of lumps in the traveling-grate roasting machine is 60%, whereas the pellets can be roasted to a degree of decarbonization of 80%. The method of thermophysical and kinetic studies that was proposed in this paper can be extended to study the laws of thermally activated endothermic chemical-metallurgical calcination processes in a wide class of iron ore raw materials. The presented computer model for calculating the limiting and optimal conditions for the operation of traveling-grate roasting machines is used for the rapid adaptation of industrial plants to the periodically changing properties of ore raw materials supplied for heat treatment.

The article considers the research methods, mathematical simulation, and calculation of heat-and-mass-transfer characteristics of film-type fills (packings) of cooling towers. The basic research approaches include experimental, numerical, and approximate methods. It is noted that the experimental and approximate methods are the most applicable for practical purposes when calculating cooling towers. One of the approximate methods consists in the application of flow structure models, namely, diffusion or cellular models. The authors consider the application of the cellular model for the gas and liquid phases in the form of an analytical solution with the thermal number of transfer units to calculate the thermal efficiency of the gas phase (air heating) and determine further the efficiency of the cooling water based on the thermal balance equation. The main parameters of the model, namely the number of cells for the gas and liquid phases, are calculated using the presented expressions. The article presents experimental data on hydraulic resistance, the volumetric coefficient of mass transfer, and thermal efficiency in the gas and liquid phases, obtained using the experimental model of a cooling tower with a bank of tubes (fill pack) with a discrete-regular rough surface. The calculation results by the cellular model are shown to agree with the experimental data. In addition, the calculation is performed for mini cooling towers with regular fills, used in rectification and absorption columns.

In this paper, a cellular automation model developed on the basis of Bezier curves with the use of a cellular automation approach for the creation of digital twins for porous nanostructures of different nature is proposed. Some numerical experiments on the creation of digital twins for the synthesized experimental samples of chitosan-based aerogels are carried out. The structural characteristics of the digital copies and experimental samples are compared, allowing us to conclude that the model is correct. The resulting digital twins can be used for predicting the properties of porous fiber materials, in particular, chitosan-based aerogels, to provide the partial replacement of real experiments by computational ones and, consequently, to decrease the expenditures on the development of new materials with specified properties.

Calculations substantiated the reproducibility of the conductometric method for the quantitative determination of the volume concentration of water added to the Essentuki-4 mineral water by analyzing the dependence of the specific electrical conductivity of the mineral water and model solutions prepared on the basis of it. The method fully complies with the principles of green chemistry, since the “waste” is mineral water diluted with distilled water.

Models describing the rheological properties of particulate-filled polymer composite materials are analyzed from the point of view of their structure. A mathematical model relating the relative viscosity to the parameters of the disperse structure is proposed on the example of a model system based on low-density polyethylene containing glass microspheres. The rheological properties of particulate-filled composite materials are considered for the first time from the standpoint of the formation of a heterogeneity by particles of a dispersed filler in space and the construction of a polymer matrix in the free space in the form of three functional components (Θ, B, and M). The use of this approach in technological practice makes it possible to estimate the melt viscosity from the parameters of a given type of structure (dependent on the content of dispersed filler) of a particulate-filled polymer composite material.

The methodology of optimization thermodynamics was used for the mathematical description and optimization of distillation processes. The following problems were considered: construction of a set of feasible operating conditions of columns separating binary and multicomponent mixtures, selection of the sequence of separation of a multicomponent mixture, feasibility of using a separating agent, selection of the feed temperature and feed point, and optimization of parallel and sequential systems of distillation columns. Calculation formulas for entropy production and heat transfer coefficients in the reboiler and reflux condenser of the column were obtained.