In modern conditions of increasing anthropogenic load on the environment, the problem of water purification is becoming particularly urgent. Pollution of natural waters with industrial and domestic waste leads to deterioration of water quality and poses a threat to ecosystems and human health. In this regard, the development of effective materials for water purification is an important direction of modern scientific research. One of the promising approaches to solving this problem is the use of membrane technologies. They allow for the effective removal of a wide range of pollutants, however, traditional membrane materials often have limited selectivity, insufficient mechanical strength or susceptibility to contamination, which reduces their effectiveness in long-term operation. In this context, polyelectrolyte complexes based on natural polymers attract special attention. The combination of carboxymethylcellulose and chitosan makes it possible to form structured materials with adjustable physicochemical properties. Such systems are characterized by biocompatibility, environmental safety and the ability to form stable membrane structures. It was found that the original polyelectrolytes Na-carboxymethylcellulose and chitosan are characterized by an amorphous and semi-crystalline structure, respectively, while the formed membranes have a new amorphous structure that differs from the structure of individual polyelectrolytes. The studied membranes demonstrated a high level of tensile strength at the level of 48 MPa and a low deformation of the order of 2 %. Such values show sufficient mechanical stability of the membranes for their use in microfiltration. The performance of the membranes was determined using a baromembrane installation under a pressure of 3, 4 and 5 atm. The studied membranes were stable at these pressure values during the test. The main parameters of the membranes were calculated: selectivity by turbidity and color. The efficiency of the purification process increases with time and increasing pressure.
The study addresses the efficiency of dry mix production technologies by focusing on mechanical fluidization as a method for reducing energy consumption during mixing processes. The aim is to establish correlations between process parameters, mixer design features, and power demand under mechanical fluidization conditions. The experimental work was conducted using vertical blade mixers operating under conditions of mechanical fluidization. Alabaster mixtures of varying particle size distributions were chosen as the model material. The methodology combined factorial experiment techniques with dimensional analysis to derive empirical relationships between power demand, blade geometry, rotational speed, and layer height. Power consumption was recorded across different operating regimes, both prior to and after fluidization onset. The experiments revealed that the onset of mechanical fluidization occurred at circumferential blade speeds within the range of 2.5–3.3 m/s. This transition was accompanied by a sharp reduction in consumed power, a visible expansion of the powder layer, and the formation of circulation zones characterized by vortices and bubble release. During this stage, mixing efficiency increased substantially while energy consumption per unit mass decreased.Two functional regimes were identified. In the initial compression phase, power demand was determined primarily by bulk density, blade inclination angle, and layer height. In the subsequent fluidization regime, additional factors such as blade-to-wall clearance and specific resistance coefficients influenced energy requirements. For alabaster with a bulk density of 900 kg/m³, resistance coefficients of c₁ = 7 and c₂ = 4 were used to establish predictive models. The derived power equations demonstrated accuracy within 10% when compared to experimental data.The dependence of mixing power on rotor speed exhibited a characteristic U-shape: power consumption decreased until reaching a minimum at the onset of fluidization, then increased again at higher speeds due to intensified turbulence and dissipation. The experiments also confirmed the presence of dissipative heating, with noticeable temperature rises within several minutes of operation. This effect emphasizes the necessity of controlling operating speed to prevent undesirable material degradation. From the standpoint of energy efficiency, the most rational operational regime was identified at speeds slightly above the threshold of fluidization. At these speeds, homogeneity and mixing intensity were high while energy consumption remained moderate. Conversely, operation at excessively high circumferential speeds led to unstable behavior, such as particle ejection and pronounced heating, which may limit industrial applicability. The empirical models developed in the study provide a practical tool for predicting mixer performance under variable conditions, allowing for optimization of design parameters such as blade geometry and clearance. This ensures flexibility in processing materials of different densities and granular structures. Industrial application of these findings promises reductions in production costs, expansion of product variety, and increased adaptability of mixing equipment to market needs. Mechanical fluidization of dispersed materials is achieved at circumferential blade speeds of 2.5–3.3 m/s, enabling significant energy savings and improved mixing performance. The proposed empirical correlations allow accurate prediction of energy parameters and provide a basis for optimizing mixer design and operation.
An extrusion die is a structurally critical component of a screw extruder that determines the quality of polymer products. Design imperfections in the die flow channels cause stagnant zones, weld lines, and non-uniform melt flow distribution. This study investigates the base and modified designs of an extrusion die used for manufacturing polymer pipes with a diameter of 54 mm and a wall thickness of 2 mm. The die material is an alloy steel with a yield strength of σy = 620 MPa, density of ρ = 7700 kg/m³, elastic modulus of E = 2.1·10⁵ MPa, Poisson's ratio of μ = 0.28, and thermal conductivity of λ = 50 W/(m·K). Numerical simulation of the stress-strain state was performed in SolidWorks Simulation using the finite element method (FEA). The boundary conditions included rigid fixture of the die end face on the flange side, an internal distributed pressure of 40 MPa, and internal and external surface temperatures of 170 °C and 172 °C, respectively. The design modifications of the improved die incorporate two structural solutions. The first features the integration of rotating bodies capable of circular motion, aligned by a cage, positioned between the mandrel holder and the channel outlet zone. This arrangement intensifies deformation and facilitates the healing of melt flow weld lines. The second solution involves a central bore and transverse grooves on the mandrel holder surface to supply and distribute a lubricating agent, thereby stabilizing the melt flow across the channel cross-section. According to the numerical analysis results, the maximum equivalent von Mises stresses for the base design are σmax = 238 MPa with a safety factor of nb = 2.6, while for the modified design, σmax = 249 MPa with nm = 2.48. The maximum stress zone in the improved die is localized on the rotating bodies that withstand the load from the melt flow. Both safety factors exceed the allowable value of [n] = 1.6. The maximum total displacements for both designs are identical at 0.02 mm; however, in the modified die, the maximum displacement zone shifts toward the rotating bodies due to load redistribution. The elastic strains are 0.0008 mm/mm for the base design and 0.0007 mm/mm for the modified design, indicating a more uniform load distribution among the components of the improved die. Both die designs exhibit sufficient structural strength under maximum operating loads. The modified design maintains strength characteristics on par with the base design while eliminating typical extrusion defects, which justifies its recommendation for practical implementation.
This paper examines the process of cleaning gas-dust flows in a modified cyclone separator equipped with conical mesh inserts and a water injection system. The aim of the study is to develop a comprehensive mathematical model capable of describing the interrelated processes of swirling flow aerodynamics, heterogeneous water vapour condensation and inertial separation of polydisperse solid particles in a cyclone apparatus with an improved internal geometry. The methodological basis of the study is the mathematical modelling of the physical processes occurring within the apparatus. The aerodynamics of the gas flow are described by the Navier-Stokes equations, taking into account the influence of the mesh inserts as a porous medium according to the Darcy-Forchheimer model. The process of heterogeneous condensation of water vapour on the surface of spray liquid droplets is modelled based on Maxwell’s diffusion equation and the equations of heat and mass transfer. The motion and separation of solid particles are described using a modified Leith-Licht model. The relevance of the work stems from the need to improve the efficiency of capturing fine particles in industrial gas cleaning systems. The scientific novelty lies in the creation of a comprehensive model that, for the first time, combines the influence of mesh inserts, heterogeneous condensation processes and inertial separation within a single computational approach. The study resulted in the introduction of a separation efficiency enhancement factor, which characterises the stabilising effect of mesh inserts on the flow structure and the intensity of particle capture. The parametric analysis carried out showed that the combined use of mesh inserts and water injection reduces the critical particle capture diameter from 4–8 to 1–3 μm and improves the efficiency of gas-dust flow purification. The practical significance of this work lies in the possibility of using the developed model for engineering calculations, optimisation of design parameters and prediction of cyclone performance during the design stage. The results obtained can be utilised in the development of highly efficient industrial flue gas cleaning systems. The proposed model forms the theoretical basis for further numerical and experimental studies of the separation processes of fine particles in new-generation cyclone separators.
In recent decades, there has been a steady increase in the global demand for sanitary types of paper (SP), and global competition for this product requires further improvement of its production technology and reduction of its cost. High-quality SP is made from cellulose, mainly from a mixture of long-fiber softwood cellulose and short-fiber hardwood cellulose. Softwood cellulose has higher values of physical and mechanical indicators, but has a higher cost and requires more energy consumption for its grinding than hardwood cellulose. The quality indicators of SP are also affected by the degree of pulp grinding, which leads to an improvement in the mechanical indicators of SP, but intensive grinding of cellulose fibers shortens their average length, which leads to a decrease in capillary absorption, porosity, and air permeability of paper. Therefore, the purpose of the study is to determine the influence of the degree of grinding and the content of hardwood cellulose on the quality indicators of SP in order to determine the optimal composition of its fibrous composition and reduce electricity consumption for grinding softwood cellulose by reducing the degree of its grinding. To obtain SP samples, sulfate bleached softwood and eucalyptus cellulose were used with the addition of polyamideamino-epichlorohydrin resin "Vodamin-115" to the fibrous mass. It is shown that for the degree of grinding of hardwood cellulose within 30–40 o Shopper-Rigler (SR), an increase in its share in the SGP composition leads to a decrease in the breaking force of paper samples in a dry state. For SHP samples in the wet state, the same dependence is observed only for hardwood pulp with a low degree of grinding — 30 оSR, but an increase in the content of hardwood eucalyptus pulp with a degree of grinding of 35–50 оSR contributes to an increase in the strength of the bonds in the SP paper sheet. It is shown that an increase in the degree of grinding of hardwood pulp and an increase in its content in the composition of paper with softwood cellulose leads to a decrease in capillary absorption. It is recommended to grind softwood cellulose to 25 оSR, hardwood cellulose to 35–40 оSR and to use a composition of 30–40 % softwood cellulose and 60–70 % hardwood cellulose with the addition of 18 kg/t of “Vodamin-115” for paper production.
The subject of the study is the design of packing with the form of solid of revolution for heat and mass exchange columns. The purpose of the article is a critical analysis of the designs of packing with the form of solid of revolution for heat and mass exchange columns, which are used in chemical, petrochemical, oil refining, food, microbiological, thermal power, fluid industrial emissions treatment systems, and other industries. One of the simplest and most effective contact elements of heat and mass exchange columns, which are used primarily in the chemical, petrochemical, oil refining, food, microbiological and thermal power industries, are packing with the shape of bodies of revolution, one of the main advantages of which is the low hydraulic resistance due to their streamlined shape, as well as the absence of stagnant zones in the packing layer. These packing primarily include contact elements in the form of straight circular cylinders and cones, balls (spheres), toruses, ellipsoids of revolution, single-cavity hyperboloids, barrels, bodies of ogival shape (ogive), as well as bodies of other streamlined shapes. Due to their symmetrical and streamlined shape, packing with the shape of bodies of revolution, primarily in the form of balls (spheres), are widely used as a moving packing in fluidized bed devices. Recently, instead of a simpler in design, but at the same time more material-intensive solid packing with a large mass and low specific surface area, lighter packing in the form of shells with elements to increase the specific surface area and turbulize the flows of the processed phases, in particular in the form of shells with a skeletal structure, which can be manufactured by 3D printing from various structural materials, are increasingly being used. The above design survey may be useful to designers and inventors in finding innovative technical solutions in the field of contact elements of heat and mass exchange columns.
The subject of the study is polymer compositions based on polyvinyl alcohol and carboxymethyl starch. The aim of the work is to comprehensively determine the rheological, sorption and physico-mechanical characteristics of polymer systems to establish optimal ratios of components that ensure the formation of biocompatible hydrogel materials with high sorption capacity, structural stability and sufficient mechanical strength, suitable for promising applications in dentistry and regenerative medicine. The methodology of the work includes cryostructuring of aqueous solutions of PVA/CMC, determination of rheological parameters using a rotational viscometer, assessment of sorption properties by measuring water absorption and study of mechanical characteristics (strength, elasticity, elongation) in accordance with international standards ISO and ASTM. The relevance of the study is due to the need to create new biocompatible dressing materials that can maintain optimal humidity, absorb exudate and provide barrier protection. Scientific news is not possible to use CMC instead of traditional carboxymethyl cellulose, which opens up new opportunities for regulating the properties of hydrogels. The main results showed that systems with a high CMC content in the PVA/CMC ratio of 0/10–7/3 have pseudoplastic behavior, while compositions with a predominance of PVA of 8/2–10/0 are characterized by dilatant properties. It was found that the highest degree of sorption is ~3900% based on 3/7, but such samples dry out quickly. The compositions 5/5 and 6/4, which demonstrate high strength of 0.31–0.37 MPa and relative development up to 457%, were identified as promising for combining sorption and mechanical properties. The field of application of the obtained materials covers modern medicine, in particular the creation of dressings, dental materials and biocompatible matrices for regenerative medicine. The practical significance of the work lies in the specific compositions that combine high initial moisture content, controlled desorption and mechanical stability, which is a critical point for wound healing and tissue repair processes.
Wastewater from dairy processing plants is highly concentrated and carbon-rich. Since the chemical oxygen demand to total nitrogen ratio here is high (COD/(Ntot) ≈ 90), the denitrification process is not limited by carbon deficiency. However, conventional technological layouts with spatial separation of aerobic and anoxic zones remain highly energy-consuming, as they require separate reactors, continuous nitrate recirculation, and high aeration intensity. The proposed hybrid SBR configuration with floating expanded polystyrene carriers overcomes these drawbacks. In such a system, aerobic and anoxic microzones co-exist simultaneously within a single biofilm under low dissolved oxygen (DO) conditions. Readily biodegradable carbon is rapidly consumed by heterotrophs in the outer (aerobic) shell of the biofilm. Consequently, a protected niche with a locally low carbon-to-nitrogen ratio is formed inside the anoxic core, ensuring high efficiency of the denitrification process. This paper describes the software implementation of a two-step ASM3_2N model with a homogenized biofilm description within the Python environment (NumPy 2.2, SciPy 1.15). The model was calibrated using laboratory data. In the baseline operating mode (DO = 1.0 mg O2/L; carrier filling ratio of 30 % by volume), it reproduces a total nitrogen removal efficiency of 86.5 % for the biofilm carrier reactor compared to 76.0 % for the control reactor, with a distinct oxygen optimum within the window of 0.8–1.2 mg/L. Local sensitivity analysis (OFAT, ± 20 %) demonstrated that among the ten parameters, the maximum growth rate of AOB (μmax,AOB) and the heterotrophic yield coefficient (YH) dominate; the oxygen half-saturation constant for nitrifiers (KO,AOB) retains its significance in the low-DO mode. The model and the resulting ranking are suitable for the preliminary design of biological treatment units and for planning experimental programs.
The work includes numerical modeling of the process of mixing a polymer composition in static mixers of various designs, namely in a classic Kenics mixer and in a new proposed modification of a blade static mixer. The relevance of the topic is due to the growing need for high-quality polymer products, for which a uniform distribution of the dispersed phase is of decisive importance in the formation of the final physical and mechanical characteristics of the material. The purpose of the study was to determine the efficiency of a new design of a static mixer, analyze the influence of its geometric and technological parameters on the dynamics of polymer composition flows and the level of homogenization in comparison with the basic Kenics design. The work has applied numerical modeling of the process of mixing a two-phase polymer composition (in a ratio of 50/50) under isothermal laminar flow conditions. To describe the rheological properties of the polymer melt, the Bird-Carrot viscosity model was used, which most adequately reflects the non-Newtonian behavior of polymers. The system of equations, including the equations of momentum, energy, continuity and volume fraction of the secondary phase, was implemented in the ANSYS Fluent software environment using the finite element method. The basic object of comparison was a Kenics static mixer with traditional geometric parameters (element rotation angle 120°, arrangement of adjacent elements at an angle of 90°). The influence of different values of the volumetric flow rate (2·10⁻⁵ – 8·10⁻⁵ m³/s) on the level of homogeneity and pressure drop was investigated. The results showed that the flow rate only slightly affects the final level of homogenization, and the resulting homogeneity drop was within 2.08–2.67 %. For the blade static mixer, various geometry configurations were considered: the thickness of the elements (10, 15 and 20 mm) and the angles of their mutual rotation (45° and 90°). It was found that the geometry of the structure has a decisive influence on the quality of mixing. The worst results were obtained when the elements were rotated by 90° regardless of the thickness, while the best level of homogenization (8.6%) was recorded for the variant with a thickness of 15 mm and a rotation angle of 45°. Although these results are inferior to the basic Kenics mixer, they confirmed the promising design, which, thanks to its modular structure, allows you to vary the number and configuration of elements, adapting the device to specific technological tasks. A comparative analysis of the pressure drop showed similar patterns in the two types of mixers - for both, a stepwise decrease in pressure along the channel is observed. However, the peak pressure values in the blade mixer significantly depended on the geometric parameters of the elements, which opens up opportunities for optimizing the design for specific requirements. In general, the study demonstrated that the classic Kenics mixer provides a significantly higher quality of homogenization of polymer compositions. At the same time, the new blade mixer has the potential for further modernization and application, given its flexibility in geometric variations and the possibility of improvement. The prospects for future work are to expand the range of geometries studied and conduct experimental tests on industrial samples of polymer materials.
The work is dedicated to the comprehensive analysis of the hydrodynamics and kinematics of granular bulk material movement in rotary tubular apparatuses, which are widely used in the chemical, construction, and metallurgical industries. The main goal of the research is to identify the patterns of dispersed flow behavior by comparing experimental data and numerical modeling. To achieve this, complex experimental and numerical studies were conducted on the movement of particles of various shapes and types, characteristic of a wide range of industrial processes. Video recording was performed on a laboratory setup, and the subsequent digital processing of the obtained data allowed for the precise determination of the coordinates, trajectories, and local velocities of the particles. The granule size in the experimental studies was 3–6 mm under conditions of drum filling ranging from 4 % to 32 % and a rotation speed of 4–85 rpm. Trajectories and particle velocity fields were analyzed, which made it possible to identify significant differences in the movement regimes and to characterize the layer structure, which consists of active and passive zones. The formation of a stable circulation core was established, around which closed movement contours arise. A quantitative analysis of the velocity regimes showed that the maximum particle velocity is observed in the open surface zone (active layer) and is 0.82–2.2 m/s, while the minimum values in the depth of the passive zone are about 0.041 m/s. Comparison with the mathematical model showed convergence with an error of 4–15 %, depending on the experimental conditions, which confirms the adequacy of the model and the correctness of the numerical methods used. The developed and implemented methodology is based on the complex application of video analysis, interpolation methods, numerical modeling, and statistical processing, which enabled the obtaining of detailed kinematics characteristics of bulk material movement in the rotary drum. The proposed approach ensures high measurement accuracy and the capability for adequate assessment of particle movement dynamics. The results confirm the high informational value and practical applicability of the methodology for engineering practice and further scientific research, particularly for the optimization of design, operating modes, model refinement, and prediction of bulk material behavior in real industrial conditions.
In this work, the effectiveness of inhibiting corrosion processes in mineralized water-oil media using a complexing amine-containing corrosion inhibitor was investigated in detail. The inhibition efficiency and corrosion rate were determined using the massometric method. According to the results of the experiments, it was found that the thiourea inhibitor was most effective in a medium with a NaCl concentration of 3 % and 10 % at pH 6-7 and doses of 10-50 mg/dm3. It was under such conditions that a significant decrease in the corrosion rate was observed compared to control samples without an inhibitor. In addition, the influence of temperature and acidity of the medium was an important factor. It was shown that at a weakly acidic pH and an elevated temperature of 80 °C, thiourea demonstrated increased inhibitory properties. At the same time, the results obtained indicate that the inhibitor is effective at lower temperatures. In particular, some of the experimental data demonstrate a high level of metal protection in environments with a fixed pH value at a temperature of 20 °C. After the conducted studies, it can be stated that the amino-containing inhibitor thiourea is a promising corrosion inhibitor for use in mineralized water-oil systems.
Modern manufacturing increasingly relies on the use of mobile robots for automation of logistics and technological operations. However, the dynamic nature of manufacturing environments creates complex scientific challenges for mobile platform control systems. Existing navigation algorithms often fail to provide an adequate balance between task execution speed, energy efficiency, and movement safety. The aim of this research is to synthesize modern methods of proactive control of mobile robots in dynamic manufacturing environments based on problem formalization through multidimensional POMDP, implementation of generative models for dynamics prediction, and multi-criteria optimization with adaptive goal balancing. A comprehensive analysis of scientific publications from 2016–2025 was conducted on the topics of autonomous navigation, multi-criteria reinforcement learning, and integration of artificial intelligence systems with industrial controllers. Systems analysis methods were used to identify unresolved scientific problems and synthesize a new control architecture. Theoretical approaches were applied including formalization through partially observable Markov decision processes, prediction methods based on generative models, and principles of multi-criteria optimization. It was found that optimal proactive control is achieved through the integration of three key components: prediction of future environmental states, multi-criteria planning considering productivity, safety, and energy efficiency, as well as adaptive goal balancing in real-time. A three-level control system architecture is proposed, which includes a prediction module based on generative models, a planning module using reinforcement learning algorithms, and an execution module based on programmable logic controllers. It is shown that the integration of high-level AI-algorithms with industrial PLCs provides a unique combination of adaptability and guaranteed safety. A mathematical model has been developed that formalizes the process of adaptive proactive control considering predicted environment dynamics and variable criteria priorities. Proactive control of mobile robots in dynamic environments requires a comprehensive approach that combines prediction, multi-criteria optimization, and reliable hardware execution. The proposed architecture creates a theoretical and practical foundation for developing a new generation of autonomous robotic systems capable of functioning effectively in complex manufacturing conditions with safety guarantees.
The study investigates the processes of tap water softening using a reverse osmosis system equipped with a low-pressure membrane Filmtec TW30-1812-75. The aim of the research was to determine the efficiency of low-pressure reverse osmosis membranes for freshwater softening and to assess the influence of water hardness on scale formation on the membrane surface depending on filtrate volume and permeate recovery rate. During the experiments, tap water with an initial hardness of 4.0–4.8 mg-eq/dm³ was treated under a working pressure of 6.1 atm and a membrane productivity of 0.0289 m³/h. The study was conducted at permeate recovery rates of 40 %, 50 %, 65 %, 75 %, and 90 %. To evaluate the process, pH, electrical conductivity, total hardness, alkalinity, and concentrations of calcium and magnesium ions were measured in both the permeate and concentrate. Experimental data were compared with theoretically calculated concentrations in the concentrate. The results showed that the Filmtec TW30-1812-75 membrane exhibited high selectivity toward hardness ions (98–99 %) compared with bicarbonate anions responsible for water alkalinity. As the permeate recovery increased, the selectivity for bicarbonates gradually decreased—from 94.8 % at 40 % recovery to 91 % at 90 %. It was also found that with an increase in the volume of permeate collected, the difference between calculated and measured concentrations of hardness and alkalinity grew, with actual values being lower than theoretical ones. This indicates the deposition of calcium ions in the form of calcium carbonate (CaCO₃) on the membrane surface. The most intensive scaling was observed at recovery rates above 75 %. At lower recovery degrees, permeate quality remained stable, and concentration variations corresponded to expected values. The Filmtec TW30-1812-75 membrane provides effective reduction of water hardness and alkalinity while maintaining stable purification performance within the studied operating range. At recovery rates exceeding 75 %, the risk of scale formation increases, which should be considered when predicting and optimizing the operation of reverse osmosis systems.
Rational use of resources in the design of technological pipelines and ensuring their growing needs requires the performance of strength calculations, which require the use of appropriate values of temperature coefficients of steels . The purpose of the article is to improve the determination of temperature coefficients of steels, the values of which are standardized by regulatory documents in force in Ukraine. Based on typical tables, dot plots of changes in temperature coefficients of steels from which technological pipelines are made depending on the temperature t have been constructed and analyzed. It is proposed to approximate these dependencies by simple mathematical equations. As a result, it was established that the dependence = f(t) for steels Ст.3, 10, 20, 09Г2С, 10Г2С1, 15ГС, 16ГС, 17ГС, 17Г1С in the range of t change from 200 oС to 300 oС is described by a simple quadratic regression = – 0,00001t2 + 0,0025t + 0,9, and when t changes from 300 oС to 450 oС – by a cubic regression = – 0,00000007t3 + 0,00006696t2 – 0,02197070t + 3,29876905. In the above and proposed formulas, the temperature t is substituted in °C. The dependence = f(t) for steel 15Х5М in the range of t change from 200 оС to 390 оС can be described by the quadratic regression = – 0,00000794t2 + 0,00336599t + 0,64421053, and when t changes from 390 оС to 450 оС – by the quadratic regression = – 0,00007917t2 + 0,06266667t – 11,64875000. The dependencies = f(t) for other steels are approximated by single mathematical equations over the entire range of temperature changes. The value of the temperature coefficient for steels 08Х18Н10Т, 08Х22Н6Т, 12Х18Н12Т, 12Х18Н10Т, 45Х14Н14В2М, 10Х17Н13М2Т, 10Х17Н13М3Т, 08Х17Н15М3Т is described by cubic regression = 0,00000002t3 – 0,00001870t2 + 0,00493000t + 0,61799999. The dependence = f(t) for steels 12Х1МФ, 15Х1МФ is described by quadratic regression = – 0,00000128t2 – 0,00016667t + 1,08461538. The value of the temperature coefficient for steel 20Х3МВФ is described by quadratic regression = – 0,00000453t2 + 0,00182667t + 0,8160. The obtained formulas allow to abandon the use of standard tables and additional interpolation of intermediate values of temperature coefficients of steels when performing calculations, which in turn simplifies both the calculation itself and the development of appropriate computer programs. The average error value of the performed approximations is in the range from 0% to 1.27%, which indicates a high level of coincidence of the regression equations with the actual values. The use of the proposed formulas for calculating the temperature coefficient of steels makes it possible to simplify the calculation of technological pipelines for strength. In the future, it is planned to continue work on improving calculations for the strength and stability of elements of vessels and apparatus in chemical and oil refining industries.
The scope of proposed research is the effects of viscous dissipation of non-Newtonian liquid flow kinetic energy on the electric equipment exploitation modes in liquid processing industry. Viscous dissipation, affecting the speed of processes, can cause an increase or decrease in energy consumption, and therefore, is an important factor in the transportation and processing of viscous liquids. Dissipation of viscous liquid flow’s kinetic energy into thermal form can cause change of operational characteristics of processing equipment in any industry involving liquid transfer, because of unpredictable changes in energy consumption and productivity of processing devices occur. Neglecting viscous dissipation effects can lead to economically irrational design of pipelines, processing equipment and pumping systems, that would reduce their overall economic efficiency. Changes in temperature and viscosity can negatively affect the quality of outcome product, especially in the food and petroleum industries. Appropriate consideration of those factors would allow to reduce costs, increase efficiency and ensure proper product quality. The research work is aimed on finding previously neglected instant effects of viscous dissipation on electric energy consumption, speed of technological processes, quality of product and general productivity of equipment of chemical industry, particularly, equipment for pumping and mixing of viscous non-Newtonian fluids. The article presents a mathematical formulation and the main aspects related to modeling non-isothermal flow using “Ansys Fluent” CFD numeric modelling software package. The results of the mathematical modelling have been verified by a physicalexperiment in a rotational viscometer of the 'cylinder-cylinder' type. The experimental study confirmed the numerical modelling and showed that during 5 minutes of processing, the temperature of the working substance increased by 6°C due to viscous dissipation of energy. In the case involving wall slip simulating a hydrophobic coating of working parts or the application of ultrasonic vibrations on the rotor, the dissipation effect looks negligible within 1°C range. But in the case of the processing of viscous media sensitive to temperature increase, effects of viscous dissipation becomes significant. The reduction of these effect is facilitated by the use of coatings or other conditions at the interface with solid walls and working parts of the equipment, which reduces the adhesion of the processed liquid to them. In the case of high-viscosity substances processing, the effects of viscous dissipation and wall slip significantly affect the process and the distribution of properties of the substance over time and space. As demonstrated by the modelling outcomes and physicalexperiment data, during the processing of a fluid with a viscosity of 0.78 Pa·s at a shear rate of 300 s-1, the temperature increase over 5 minutes was 6 °C. At the same time, at wall slip, which in thenumerical model imitates the thin-layer lubrication or hydrophobic coating on the working elements, the temperature increase over the same period was only 1°C. This leads us to assertion that hydrophobization and modifying friction additives will influence the level of dissipative heating of substances. The task of further research involves physical experiments on the processing of viscous substances in equipment with hydrophobic coating and various lubricating layers.
The subject of research is industrial and household equipment and devices, which as a whole or their structural elements are made in the form of a Möbius strip. The purpose of the research is a critical analysis of the use of the Möbius strip in engineering, technology and everyday life. One of the most important characteristics of elements of various machines, apparatuses, devices, and structures is their geometric shape, which is especially evident in mechanical engineering, aerodynamics and hydrodynamics, and heat and mass transfer. One of the geometric objects with atypical and unique properties is the Möbius strip (sheet, ring, Möbius loop) – a topological object that is the simplest unoriented surface with one side and one edge. The main advantage of the Möbius strip is precisely the presence of one surface, which is widely used in a wide variety of areas of human life, and primarily in engineering and technology. The Möbius strip has found its application in mechanical and instrument engineering, chemical technology and related industries, thermal power engineering, renewable energy, construction, light industry, agriculture, transport, aerospace and military technology, electronics, radio engineering, computer technology, medicine, advertising and jewelry, entertainment and recreation, personal hygiene products, as well as in everyday life. In developing innovative technical solutions, the use of the Möbius strip in various sectors of the economy and everyday life can provide significant assistance not only from the more than one and a half century of experience of scientists, engineers, and inventors in this matter, but also from the unique capabilities of artificial intelligence. This review may be useful to creators of new equipment and technology, because when creating new developments, a fund of technical, including geometric, effects is widely used, which is an integral part of the information fund of inventors, designers, and scientists and helps them create innovative solutions to technical problems.
The study is aimed at analyzing the level of atmospheric pollution by the enterprise PrJSC "Ukrgrafit", determining carcinogenic and non-carcinogenic risks to public health, as well as developing recommendations for minimizing harmful effects in the context of sustainable development and post-war restoration of the industrial sector. The object of the study is the impact of pollutant emissions of PrJSC "Ukrgrafit" on the environment in the city of Zaporizhzhia. Mathematical modeling of emission dispersion was performed using the ISC-AERMOD View software environment. The assessment of risks to public health was carried out in accordance with the methodology of Human Health Risk Assessment. To determine the optimal ways to minimize pollution, a comparative analysis of international experience in implementing environmental technologies in the carbon graphite industry was carried out. The results of the study showed that one of the most significant pollutants in the emissions of PrJSC "Ukrgrafit" is undifferentiated dust, in particular, suspended particles PM10 and PM2.5. The total volume of particulate emissions is 250.76 t/year. When modeling the inhalation exposure of priority pollutants in 80 receptor nodes and 11 control points, no exceedances of permissible concentration levels were recorded. Exceedance of the minimum level of total non-carcinogenic risk from emissions of all prioritized pollutants at receptor network nodes and control points under the condition of acute inhalation exposure is observed at a distance of 500 m in all directions along the cardinal points, except for the west and north-west directions. Hazard coefficients (HQ) for individual substances did not exceed the level of HQ ≤1, which indicates a minimal risk to public health. The carcinogenic risk due to the presence of benzo(a)pyrene is estimated at the level of ICRtotal <1×10-6, which corresponds to the minimal risk according to the classification of the World Health Organization. The levels of individual risk of death (IRM) from exposure to PM10 particulate matter at receptor nodes and control points correspond to a conditionally acceptable risk that requires constant monitoring. Analysis of pollutant concentrations in the surface layer of the atmosphere did not reveal significant excesses of permissible standards, but showed a potential impact on the health of the population living in the area of influence of the enterprise. This emphasizes the need to increase the efficiency of environmental control and improve the enterprise's gas purification systems to ensure sustainable development and reduce the man-made load on the environment. To minimize the negative impact of the enterprise, a set of measures has been proposed, which include the modernization of gas purification systems, strengthening environmental monitoring and adaptation to international environmental standards. The introduction of regenerative thermal oxidation (RTO) will reduce the concentration of organic compounds in emissions by 90%. Additional installation of bag filters will help reduce the level of PM10 and PM2.5 particulate matter by 99%. To ensure transparency of environmental monitoring, it is necessary to expand the network of automated air quality control stations, which will allow real-time data on the level of pollution and prompt action to be taken. The proposed measures will significantly reduce the level of pollution and adapt the enterprise to international environmental standards, contributing to the sustainable development of the industrial sector of Ukraine.
The article examines the mathematical modeling of the methane tri-reforming (TRM) process based on the conservative-perturbed equilibrium (CPE) phenomenon. A comprehensive approach to modeling the TRM reactor in the COMSOL Multiphysics environment with integration of data obtained in DWSIM and MATLAB is proposed. A model of a plug flow reactor as an object with distributed parameters was obtained and studied, taking into account heat and mass transfer processes and chemical reaction kinetics on a nickel catalyst. The possibility of achieving super-equilibrium concentrations of the target product in transient CPE modes is demonstrated, which significantly increases the process efficiency. Based on the obtained temperature profiles and flow distribution analysis, a strategy for automated reactor control has been developed, aimed at maintaining optimal reaction conditions. It was established that the application of the proposed approach provides a stable temperature regime without sharp temperature drops along the reactor, which contributes to increased productivity and energy efficiency of the process. Temperature distributions of the coolant and gas mixture were obtained both along the length and in the cross-section of the reactor. This allows maintaining an optimal temperature distribution, avoiding overheating (energy efficiency) and ensuring a greater yield of the target product due to the conservative-perturbed equilibrium effect. The numerical methods such as finite difference method and finite element method, widely used for modeling heat and mass transfer processes, are implemented in various software packages, including MATLAB, ANSYS, and COMSOL Multiphysics, which allow for accurate calculations of process dynamics in reactors. The obtained results have practical significance for the automation of complex thermochemical systems with distributed parameters and optimization of their temperature regimes.
Oil and petroleum products are among the most hazardous pollutants affecting all stages of technogenesis. They pose a particular threat to soil ecosystems, which play a crucial role in biogeochemical cycles and the maintenance of ecological balance. Understanding the transformations that occur in soil under the influence of varying oil concentrations, as well as the responses of soil microorganisms to such contamination, is essential for the accurate assessment of soil ecosystem conditions and for selecting effective remediation strategies under specific circumstances. The aim of this study was to investigate the response of different components of soil microbiota—namely, various physiological groups of bacteria and microscopic fungi—to oil pollution across a wide concentration range. Experimental research was conducted on soil samples artificially contaminated with oil at the following concentrations: 1, 5, 10, 50, 100, 200, 300, and 500 cm³/kg. The results revealed a significant linear increase in the number of microorganisms from various ecological and physiological groups within the 10–100 cm³/kg concentration range. However, a further rise in oil concentration led to a marked decrease in bacterial abundance, except for hydrocarbon-oxidizing bacteria, which remained relatively stable. At the highest contamination level (500 cm³/kg), the soil microbiota was nearly completely suppressed, with only spore-forming and hydrocarbon-oxidizing bacteria persisting, indicating their ability to withstand toxic stress. Unlike bacteria, microscopic fungi exhibited a sharp decline in colony-forming units (CFU) at moderate oil concentrations (10–100 cm³/kg). Nonetheless, their abundance remained relatively stable at higher oil concentrations, and at 500 cm³/kg, the number of fungal CFUs was nearly twice that of bacteria. This suggests the presence of adaptive mechanisms in certain fungal taxa that enable survival under severe oil contamination.
This study explores the kinetics of oxygen removal from water using sodium metabisulfite (Na₂S₂O₅) in the presence of iron(II) ions as a catalyst. The research addresses the urgent need for effective and environmentally safe deoxygenation methods, particularly in thermal energy systems where dissolved oxygen causes severe corrosion of metallic surfaces, especially in steam generation processes. Conventional corrosion inhibitors are often ineffective or unsafe for use in such systems. Therefore, deoxygenation remains the most viable approach for preventing oxygen-induced corrosion in industrial water systems. The paper provides a comprehensive analysis of existing water deoxygenation techniques, including physical methods (thermal, vacuum, barbotage), gas-based methods (air stripping, nitrogen or hydrogen saturation), and chemical methods. Among chemical reagents, hydrazine is recognized as highly effective; however, its high toxicity and handling complexity limit its industrial application. Sodium sulfite and its derivatives offer safer alternatives, though their effectiveness can be limited by slow reaction kinetics and the need for subsequent removal of oxidation by-products such as sodium sulfate. To enhance the efficiency of sulfite-based deoxygenation, the authors investigate the catalytic role of iron(II) ions in accelerating the oxidation of sodium metabisulfite by dissolved oxygen. The experimental work involves adding controlled concentrations of sodium metabisulfite and iron(II) sulfate to aerated distilled water and measuring the concentration of oxygen over time using a dissolved oxygen meter. Experiments were conducted under static conditions at room temperature, with variations in Na₂S₂O₅ concentration (50–300 mg/dm³) and Fe²⁺ concentration (0.1–0.5 mg/dm³). The results demonstrate a strong dependence of the oxygen removal rate on both the concentration of the reducing agent (sulfite) and the catalyst (iron ions). At low concentrations of both reagents, the oxygen binding process follows third-order reaction kinetics, with the rate depending simultaneously on the concentrations of oxygen, sulfite, and iron. As the concentrations increase, the reaction order decreases, transitioning to second-order and, eventually, first-order kinetics. At higher levels of sulfite (200–300 mg/dm³) and iron (≥0.5 mg/dm³), the rate-limiting step becomes the oxygen concentration alone, indicating that excess reductant and catalyst are present throughout the reaction duration. The authors calculated reaction rate constants for various concentration combinations and confirmed the reaction order using integrated rate equations. The findings highlight the significant catalytic effect of iron(II) on the rate of oxygen removal, even at low concentrations. The study also proposes a reaction mechanism involving the formation of iron hydroxide complexes and their subsequent oxidation–reduction cycles with sulfite and oxygen. The research contributes to the optimization of chemical deoxygenation processes in water treatment systems, especially for thermal power and heating applications. By understanding the kinetic dependencies and optimizing reagent dosages, industrial operators can achieve faster and more efficient deoxygenation while minimizing reagent consumption and environmental impact. The study emphasizes the potential of sodium metabisulfite as a practical and safer alternative to hydrazine in oxygen removal applications. Future work will focus on evaluating the influence of pH and temperature on the kinetics of oxygen removal by sodium sulfite and metabisulfite, with the goal of further refining deoxygenation technologies under varying operational conditions.
