Статті КЕТтаОП (ДМетІ)

Permanent URI for this collectionhttp://crust.ust.edu.ua/handle/123456789/14989

ENG: Articles

Browse

Now showing 1 - 40 of 55

Active Thermoregulation in Lasius Fuliginosus Nests in Spring (Hymenoptera: Formicidae)
(Sapienza University of Rome, Rome, Italy, 2025) Stukalyuk, Stanislav; Radchenko, Yury M.; Balabukh, Vira
ENG: The aim of the study was to investigate characteristics of temperature conditions in Lasius fuliginosus nests in spring to possibly prove the spring warmup hypothesis. In spring (05.03 to 31.05.2024), 3 loggers, allowing measurements of temperature conditions were mounted on the outer walls of 3 L. fuliginosus nests in a deciduous forest near Kyiv (Ukraine). The temperature measurements were taken at 15-minute intervals. Simultaneously, the atmospheric air temperature was measured during the same period (at 3-hour intervals). Nests 1 and 2 were typical for this species: both in empty cores of oak trees (1 m diameter), while Nest 3 was auxiliary and located under a 0.05 m layer of oak bark. The physical data (air and nest wall temperatures) were used to construct a mathematical model of the thermal processes occurring in the core of a carton nest. The modelling showed that the anthills’ ability to maintain nest temperature in spring depends on their size and location inside the tree trunks exposed to environmental influence. The temperature inside a nest follows the average daily air temperature with a slight delay due to thermal inertia of the tree. The nest in tree #1 proved to be the most stable: even during cold spells as low as -5°C, the temperature in the core remained +25°C thanks to metabolic heat. Nest #2 also maintains the required temperature (+25°C) during temperature falls to +5°C. However, nest #3 does not provide conditions for offspring development during sudden cold snaps: the heat emitted is insufficient to compensate for losses at air temperatures below +20°C. This nest is not designed for active thermoregulation. It has been shown that L. fuliginosus are able to actively warm up their nest in spring, and the warmup rates (up to 25–26°C) are similar to the temperature conditions in the red forest ants’ anthills (Formica rufa group).
Analysis of CFD Modelling Results of Designed Uniflow Vortex Tube Models
(Energetická konzultačná agentura n.o., Prešov, Slovak Republic, 2025) Muzychka, Ihor; Kizek, Jan; Menkov, Andriy; Karakash, Yevhen O.; Kulikov, Andrii
ENG: This study presents the results of CFD modelling of a uniflow Vortex tube based on the Ranque-Hilsch effect. The designed models are based on experimental measurements and calculations presented in [1], with the calculations derived from relationships published by Takahama [2] and Soni [3]. The tube geometry was designed according to these relationships for an inlet pressure of 0.5 MPa, which was also used in the CFD simulations. Two different inlet air geometries were tested. The analysis focused on velocity and temperature fields in the developed mathematical models. The results will serve as a basis for the design of experimental devices.
Application of Physical and Quantum-Chemical Characteristics of Epoxy-Containing Diluents for Wear-Resistant Epoxy Compositions
(MDPI, Basel, Switzerland, 2025) Kulikov, Andrii; Sukhyy, Kostyantyn M.; Yeromin, Oleksandr O.; Fedak, Marcel; Prokopenko, Olena M.; Sukha, Iryna V.; Poloz, Oleksii; Mikats, Oleh; Hrebik, Tomas; Kulikova, Olha; Lopusniak, Martin
ENG: Low-viscosity epoxy-containing diluents are used to reduce the initial viscosity of highly filled, wear-resistant epoxy systems and to improve filler wetting and dispersion. This study determined physical parameters by an atomic-increment approach and electronic descriptors using the Parametric Method 3 (PM3) semi-empirical method. Clear relationships were established between the effective molar cohesion energy and the solubility parameter with van der Waals volume. Linear dependencies were also obtained between the diluent surface tension and spreading coefficients on model high-hardness fillers, including silicon carbide, boron carbide, and normal corundum. The activity of epoxy diluents depends on the lowest unoccupied molecular orbital energy. These diluents influence processing and the final physical and mechanical properties of composites, making their selection critical for strength, hardness, and wear resistance. Computational analysis enables prediction of diluent behavior, reducing experimental time and cost. Integrating physical and quantum-chemical data into epoxy diluent design accelerates the search for optimal components and improves production of durable, high-performance epoxy composites.
Calculation of the Probability of Test Object Compliance with the Specified Requirements and Non-Binary Decision-Making Rules
(MM Publishing s.r.o., Praha, Czechia, 2024) Rimar, Miroslav; Fedak, Marcel; Kulikov, Andrii; Bilonozhko, M. V.; Rudko, K. V.; Martynova, V. V.; Yeromin, Oleksandr O.; Savvin, Oleksandr V.; Sukha, Iryna V.; Krenicky, Tibor
ENG: The probability of test object compliance with the specified requirements and non-binary decision is a measure of how likely the test object is to meet the criteria for acceptance or rejection based on multiple factors. It is necessary to calculate by using a valid mathematical model that takes into account the test object's characteristics, the test conditions, the test criteria, and the uncertainty of the measurements. The significance of the probability of test object compliance with the specified requirements and non-binary decision can help to evaluate the quality, reliability, and performance of the test object, as well as to support decision making in complex situations.
Characteristics of Thermal Processes in Ant Nests Built Under Stones (Hymenoptera: Formicidae)
(“Charles Darwin” Sapienza University of Rome, Italy, 2022) Stukalyuk, Stanislav; Radchenko, Yury M.
ENG: Ants prefer to nest under stones. This is due to temperature regimes favorable to the development of ant broods. In this paper, we investigated the influence of stone and ambient parameters on ant nests and created a model of thermal processes in ant nests under stones. The simulation results were compared with temperature measurements. Temperature was measured under 20 stones under different illumination conditions (sun, penumbra and shade) for 3 ant species (Myrmica rubra, Formica cinerea, Lasius niger) in Ukraine from April to August 2021. Stones were categorized as hot, warm and cold. Each stone was checked once a week for the number of workers and brood. Under two stones, tem¬perature was measured using loggers. The number of workers under hot stones in spring increased three weeks earlier than under cold and warm ones. In May-June, the maximum number of workers was recorded under hot stones. In July, the number of ants was minimal under all categories of stones. Larvae appeared under hot stones two weeks earlier than under other categories of stones. In August, the number of pupae under cold and warm stones was greater than under hot ones. Number of larvae and pupae was positively influenced by the diameter of the stone, whereas stone height did not exert an important role. Ants preferred to inhabit nests under large flat stones, which are easily heated in spring and warm the soil under them. Another important characteristic was the location of the stones. The highest brood development was noted in nests under stones in open areas well lit by the sun in the daytime. In summer ants migrated from under hot stones, because soil under it dry and warmed. Stones and their position may be important factors in accelerating the development of brood in colonies of ant species that do not have active thermoregulation.
Determination of Operating Parameters of Accumulative Electric Heating Systems
(IOP Publishing Ltd, 2024) Kolienko, Anatoliy G.; Ahmednabiev, R. M.; Gupalo, Olena V.; Demchenko, O. V.; Hukasian, O. M.
ENG: The article presents the results of research aimed at determining the parameters and characteristics of storage heating systems, justifying the possibility of using heat accumulators to increase the efficient use of energy that is generated, including from renewable sources. The virtuality, frequency and significant dependence on natural conditions and climate of renewable energy sources, as well as the need to optimize their installed capacity, leads to the need to use energy storage installations. The presence of efficient energy batteries is a prerequisite for modern efficient energy and heat supply systems. The methodology of the work is based on our own theoretical and experimental studies, which provide practical recommendations for the arrangement of energy accumulators obtained using renewable heat sources. This is especially relevant for Ukraine during the period of active military operations on its territory, the destruction of traditional energy sources and a shortage of generating capacity. Recommendations have been developed for the design of heat accumulators for heating systems of residential and public buildings. Their effectiveness has been assessed under conditions of limited use of fossil fuels and the use of hybrid energy sources. Scientific and practical results of the work make it possible to carry out low-cost reconstruction of heating systems for the introduction of storage systems using electrical energy, the source of which is wind and solar energy. Such developments are becoming particularly relevant in Ukraine, taking into account the requirements for ensuring the stability and efficiency of infrastructure facilities in war conditions.
Development of a Mathematical Model for the Energy Balance of the Laser Cladding Process of Metallic Powders with a Coaxial Nozzle
(MM Publishing s.r.o., Praha, Czechia, 2024) Karakash, Yevhen O.; Rimar, Miroslav; Karpovych, Olena; Zhumar, Denys; Kizek, Jan; Fedak, Marcel; Kulikov, Andrii
ENG: Modern technologies require innovative solutions for producing complex structures from various materials. Additive manufacturing (AM) or 3D printing presents such a challenge and has significantly impacted the environment across manufacturing sectors, regardless of size. Researchers and technicians have developed new design approaches by exploring fundamental components, materials, and manufacturing processes beyond traditional frameworks, addressing global complex material and design challenges. Laser cladding of metal powders with a coaxial nozzle is one such technology, offering highly productive processes for large-scale component production. Fiber lasers are optimal for providing laser radiation, ensuring required emission quality and stability. The authors seek to develop a mathematical model for the energy balance of coaxial laser cladding of metal powders, aiming to provide an overview of energy consumption levels and unit characteristics for powder delivery, inert gas, and laser radiation sources in direct metal powder coating setups.
Effect of Urban Habitats on Colony Size of Ants (Hymenoptera, Formicidae). In Memory of Professor A. A. Zakharov (Russian Academy of Sciences, Moscow)
(Turkish Academic Network and Information Center, 2022) Stukalyuk, Stanislav; Akhmedov, Ascar; Gilev, Alexey; Reshetov, Alexander; Radchenko, Yuri M.; Kosiuk, Nataly
ENG: Urbanized ecosystems are suitable for the habitat of only a few species of ants, due to conditions caused by human activities. Invasive species of ants have adapted to urbanized ecosystems most successfully. The study of the ant colonies sizes started in Crimea in 2013–2014. In 2019–2021 it was carried out in Ukraine (the Carpathians, Kyiv city, and Kyiv region), in Russia (Rostov-on-Don city and region, and the Urals), and in Uzbekistan (Tashkent city, and tugai forests). The study covers natural (forest, meadow, steppe), suburban (alleys and tree planting) and urban habitats (tree planting along streets and roads, botanical gardens). Our study covers 21 species of ants with trails on forage areas. Nine species were sampled for interspecific comparison of colony sizes. They were collected in at least 2 habitat types within the same geographic region. According to the activity parameter on the trails, the number of foragers and the population of the colony were calculated (using the formula of A. Zakharov). According to our calculations, the maximum colony sizes are typical for invasive species (Crematogaster subdentata, Lasius neglectus, 100–7500 thousand workers) in the urban habitats. Some native species (Dolichoderus quadripunctatus, Formica cinerea) in the urban areas have colonies with 120–350 thousand workers. These values may exceed those for ant species inhabiting natural habitats (30–250 thousand workers). High rates of colony size in the urbanized habitats can be achieved due to availability of food, nesting resources, and the absence of competing ant species.
Identification of the Thermal Process in an Induction Motor
(Dnipro University of Technology, Dnipro, Ukraine, 2022) Kuznetsov, Vitalii V.; Tryputen, M.; Nikolenko, Anatolii V.; Tsyplenkov, Dmytro; Kuvaiev, Victor; Savvin, Oleksandr V.
ENG: Purpose: synthesis of a mathematical model of an asynchronous motor, taking into account the impact of changes in the quality of electricity on the processes of heating and heat exchange for an economically justified choice of means of protection. Methodology: Theoretical substantiation of the expediency of using a one-mass thermal model of an asynchronous motor, for the conditions of operation of the latter in conditions of low-quality electricity, in order to determine losses in it. Results: Experimental studies of the operation of an asynchronous motor at nominal load were carried out. The obtained results of the measurements made it possible to determine the parameters of the single-mass thermal model, the heat transfer coefficient of the engine, and the coefficient of its heat capacity. A single-mass thermal model of an induction motor is a mathematical model used to describe the thermal processes occurring in an induction motor. This model is based on the assumption that all motor elements can be combined into one mass that heats up during engine operation. The model assumes that the thermal capacity of the motor is a constant, and the heat flow that is released during the operation of the motor is proportional to the square of the current passing through the motor windings. In addition, the model assumes the presence of thermal conductivity between the mass of the motor and the external environment, which affects the rate of heat dissipation. Scientific novelty: A methodology for determining losses in an asynchronous motor using a synthesized mathematical model is proposed, taking into account the influence of changes in the quality of electricity on the processes of heating and heat exchange in it. Practical significance: The obtained results indicate the adequacy of the proposed thermal model of an asynchronous motor operating in a network with low-quality electricity. Taking into account the fact that for many types of engines in the reference literature, there are no necessary data on the coefficients of heat transfer and heat capacity, and only the thermal time constants for certain types of engines are given, the value of the specified parameters of the model can be obtained on the basis of the methodology presented in the work. A single-mass thermal model can be useful for analyzing the thermal processes occurring in an induction motor and for improving the efficiency of the motor. In particular, it can help determine the optimal operating temperature of the motor, as well as calculate the necessary cooling system to ensure stable operation of the motor under conditions of variable load and temperature conditions.
Improvement Quality of Preparation Specialists in Area of Mathematical Modeling
(НМетАУ, Дніпро, 2021) Yasev, Aleksandr Georgievich
ENG: Improvement quality of preparation specialists in area of mathematical modeling is an actual problem in education students (especially applied) and non mathematical specialties. For solving this problem must be used system and successive exposition of maintenance of the stages of building model with obligatory demonstration of there intercommunications. Each stage of modeling makes some part of quality of model. Most difficult stage is idealization of original, because in this case the most important properties of original must be distinguished and the experimental samples of output of variables of original and calculation samples of model are got.. Main attention it must be spared to estimation of adequacy original and model with the help of famous nonparametric criteria such as criterion Wilcoxon and special criterion for small samples. Last part of modeling usually is optimization parameters of original. Methodology of study, that provides a receipt of the deeper and complete understanding of essence of mathematical modeling of technical objects is offered. Positive results are achieved by using method which is proposed. System exposition of material and accent on research and proof adequacy of model allow to attain the deeper and complete understanding of essence of mathematical design of technical objects and promote efficiency of preparation of specialists in area of the applied mathematical modeling.
Improving the Technology of Using Freon-Steam Turbines in Mine Power Complexes
(IOP Publishing, 2022) Kirsanov, Mykhailo; Slobodiannykova, Inna; Gupalo, Olena V.
ENG: Mining power complexes can significantly reduce the cost of production of mining enterprises and increase their competitive position in the relevant market. To solve the urgent problem of further improving the operation of mine energy complexes, it is proposed to include in their composition installations for the useful use of energy from low-potential sources with a freon-steam turbine, which implement the thermodynamic Rankine cycle. The article considers the features of the organization of the Rankine cycle depending on the properties of freons. When choosing freons, the emphasis is placed on the use of strictly ozone-safe freons that meet modern requirements for normalizing the value of the global warming potential. The previously proposed method for calculating the thermodynamic parameters necessary for evaluating useful action’s coefficient of using specific freons in a useful energy recovery equipment has been improved. The calculation of the energy efficiency of the equipment with a freon-steam turbine for the selected options for the use of freons is performed. The analysis of the obtained results showed that the use of ozone-safe freons with low values of the global warming potential in installations for the utilization of energy from low-potential sources will improve the operation of mine energy complexes.
The Influence of Initial Parameters on the Process of Synthesis Gases Cooling during Plasma-Chemical Processing of Carbon-Hydrogen Containing Raw Materials
(IOP Publishing Ltd, 2025) Radchenko, Yurii M.; Shevchenko, Volodymyr; Oparin, Serhii; Gupalo, Olena V.; Davydov, Serhii
ENG: The paper investigates the influence of the productivity of plasma-chemical processing of carbon-hydrogen containing raw material and initial parameters of syngas on the performance of syngas cooler. The syngas cooler consists of a sequentially located radiation section, a preliminary convective section, a steam superheater, a main convective section, an economizer, and an autonomous water cooler. To determine the operating parameters of the syngas cooler, a well-known methodology based on the solution of heat transfer and heat balance equations was used. The main performance indicators of the basic cooler design (steam capacity, superheated steam temperature, heat utilization coefficient of syngas) were determined for the ranges of 100 - 400 m3/h and initial temperature of syngas 2000 °C. The research results were summarized in the form of analytical dependence of the total area of heat-exchange surface of the cooler on the flow rate of syngas in the range from 100 to 400 m3/h, which can be used in optimization of equipment for plasma-chemical technology of hydrogen production at minimum of total costs.
The Influence of Reactive Power Compensation Methods on the Burning Characteristics of Shunted Electric Arc in an Ore Reduction Furnace
(Dnipro University of Technology, Dnipro, 2024) Nezhurin, Vadym I.; Nikolenko, Anatolii V.; Tsyplenkov, D.; Bobrov, O.; Fedorov, Serhii S.; Savvin, Oleksandr V.
ENG: The purpose of the work was to study the effect of compensation on the stability of the combustion of an electric arc in the furnace bath. Methodology. The results of the research of operating furnaces by traditional methods, such as measurement and oscillography of the form of voltage and current on the electrodes during the smelting of ferroalloys, were used. Results. Schemes of transverse capacitive compensation on the high or medium voltage side and longitudinal capacitive compensation in the medium voltage circuit of the furnace transformer are used for Electric ore reduction furnaces. Electric ore reduction furnaces are large consumers of reactive power, and their power has already reached such an amount that the value of the inductive voltage drop becomes unacceptably large; and their natural power factor does not exceed the value of 0.6–0.7. Compensation of the reactive power of the longitudinal compensation devices is traditionally resolved by usage of capacitor banks. Determined that longitudinal compensation devices are based on the phenomenon of voltage resonance, then if there are active, inductive and capacitive resistances in the furnace circuit – the arc burns continuously, even in the case of partial compensation. This mode occurs at a power factor of about 0.85. In case of full compensation of the inductive component of resistance of the furnace circuit, the mode of arc burning changes and becomes intermittent. Scientific novelty. Determined that with a fixed value of the power factor and the value of conductivity bc, it is very difficult to achieve ideal current resonance, and when bc = −⌂bl+bl+⌂blс the burning mode of the electric arc will be continuous; however, if the capacitive conductivity becomes more inductive, overcompensation is possible. In the case of transverse compensation, the total power of the furnace unit should be approximately 10% higher. Practical significance. The results obtained can be used for a reasoned selection of reactive power compensation installations for existing ore reduction electric furnaces. With full compensation of the reactive power (transverse and longitudinal), the arc burning mode of the ore reduction furnace becomes intermittent.
Method of Sequential Approximation in Modelling the Processes of Heat Transfer and Gas Dynamics in Combustion Equipment
(MDPI, Switzerland, 2022) Rimar, Miroslav; Yeromin, Oleksandr O.; Larionov, Grigoriy; Kulikov, Andrii; Fedak, Marcel; Krenicky, Tibor; Gupalo, Olena V.; Myanovskaya, Yana V.
ENG: The behavior of the processes taking place in furnaces determines the efficiency of fuel chemical energy utilization, the quality of the final products and the environmental safety of the production. Mathematical models of the processes of gas dynamics and heat transfer in the working space of heating equipment are quite complex, and do not allow the establishment of a direct analytical relationship between the quality indicator of the process (F) and the influencing parameters (xi). To simplify the procedure for obtaining the values of the function F depending on the change of parameters xi, a method of successive approximation is presented in the article. The main idea of the method is that the representation of the function around a point from the domain of the function can be extended to the entire domain for many problems of mechanics. The relative error in the definition of the function acquires its maximum value at the border of the area, and a reasonable narrowing of it allows control of the size of the error. Thus, the advantages of using the method are obvious; it is able to provide approximation of the function in a multiplicative form with a controlled error. The distribution of the method to the field of heat transfer problems is presented in this paper. The successful implementation of this method for solving problems of this kind shows that the solution of practical problems may be generalized for the entire domain of the function, despite the fact that the errors of such a representation increase to 5–7% when approaching its limit, which, however, may be considered acceptable for engineering calculations.
Mixed Colonies of Lasius Umbratus and Lasius Fuliginosus (Hymenoptera, Formicidae): When Superparasitism May Potentially Develop into Coexistence: a Case Study in Ukraine and Moldova
(Organisation for Conservation and Study of Biodiversity (CSBD) in collaboration with ANeT-India, 2021) Stukalyuk, Stanislav; Radchenko, Yury M.; Gonchar, Oleksiy; Akhmedov, Ascar; Stelia, Valery; Reshetov, Alexander; Shymanskyi, Artem
ENG: In 2015, in the territory of Kyiv (Ukraine) and in 2012-2017 in Transnistria (Moldova), two mixed colonies consisting of two species of ants – Lasius fuliginosus and L. umbratus were observed. Another 2 mixed colonies were discovered in 2021 in the territory of the city of Rivne (Ukraine). The aim of the study was to describe the observed mixed colonies, analyze the interaction of workers of two species on the trails, and by mathematical modelling to determine the probability of preserving queens of both species as part of a mixed colony. On the trails of the colonies from Kyiv and Rivne, the number of workers of L. fuliginosus is slightly higher than that of L. umbratus, so is the number of L. Fuliginosus workers in the colony. Workers of both species were making contact both within the same species and interspecific contacts, but trophobiosis with aphids has been recorded only by L. fuliginosus. The most likely of the 4 options considered was the survival of the queens of both species, otherwise the dynamics of the population over 6 years of development (total population of the mixed colony from Kyiv: 27 thousand workers of L. umbratus, 72 thousand workers - L. fuliginosus and two colonies with same population from Rivne) is difficult to explain. The possibility of such mixed colonies co-existing for at least a few years is debated.
Modeling of Thermal Processes in DED Using SolidWorks Simulation
(Energetická konzultačná agentura n.o., Prešov, Slovak Republic, 2024) Karpovich, Olena; Zhumar, Denys; Karakash, Yevhen O.; Karpovich, Ivan
ENG: The study analyzes software products for numerical modeling of additive processes performed using SLM and DED technologies. Determining temperature fields in DMD processes is an important and complex task. Based on previously determined experimental data on the volume of molten material added during cladding, the thermal processes during laser cladding of powder materials were modeled in the SolidWorks system. This allowed determining the distribution of temperature fields on the substrate and in the cladded material over time.
Modeling of Thermophysical Properties of Carbon Dioxide in the Range of Turbine Operating Parameters Based Low-Potential Thermal Resources
(IOP Publishing Ltd, 2026) Kirsanov, Mykhailo; Gupalo, Olena V.
ENG: The efficient use of secondary and natural energy resources to generate additional electricity is an important factor in improving the economic performance of industrial sectors. In the mining industry, considerable volumes of secondary and renewable heat resources with temperatures between 27 and 75ºC are available. Their effective utilization is possible through gas turbine systems operating with carbon dioxide as the working fluid. Although thermodynamic tables for carbon dioxide exist, they are difficult to apply in analytical studies involving variable parameters. Simplified analytical equations have been developed for carbon dioxide thermodynamic properties at several isobars within typical gas turbine pressure ranges. However, to determine and analyze optimal gas turbine operating modes when using low-potential heat resources from mining enterprises, it is necessary to have analytical expressions covering the entire temperature and pressure range relevant to turbine operation. Developing such equations was the main objective of this work. The study also demonstrates their practical application using specific thermal source parameters.
New Working Fluids for the Use of Heat Secondary Sources in Mining Technologies
(IOP Publishing, 2023) Kirsanov, Mykhailo; Gupalo, Olena V.; Podoliak, Kostiantyn
ENG: Production cost of mining enterprises can be significantly reduced when using secondary heat. A large volume of secondary heat sources has a temperature potential of no higher than 50ºС. To generate additional electricity using secondary heat it has been proposed to use installations with the Rankine thermodynamic cycle in mining enterprises. The paper aim is to study the thermodynamic efficiency of using R-1234yf and R-744 in the equipment, which uses the secondary heat of mining technologies for evaporation of these working fluids. R-1234yf is a freon that belongs to the class of hydrofluoroolefins and has a much lower level of global warming potential than other ozone-depleting substances. R-744 is carbon dioxide, which belongs to a natural, non-toxic and non-flammable working substance. It has been determined that the thermodynamic efficiencies of using R-1234yf and R-744 are 10% and 6.3%, respectively. The thermodynamic efficiency has been calculated for the temperature range from 50º to 20ºC, which is typical for a large volume of secondary heat sources in mining technologies.
Nonlinear Analysis of Bifurcatory Properties of Mathematical Model of Subpopulation Dynamics in the Case of a Single Niche for Subpopulation
(IEEE, 2022) Kuzenkov, Olexandr; Busher, Victor; Chornyi, Oleksii; Nikolenko, Anatoliy V.; Kuznetsov, Vitaliy V.; Savvin, Oleksandr V.
ENG: The article is devoted to the use of mathematical models of the dynamics of heterogeneous populations, and computer simulation based on the above models allows to identify general trends in subpopulations, predict the state of the system and obtain results on possible consequences of artificial intervention. Also, the use of mathematical models can predict the spread of genetic anomalies. The authors propose a model of subpopulation dynamics with a logistic function as a basic one. It is concluded that the system-wide dynamics of subpopulation processes depends not only on the reproductive potential of subpopulations, but also on the intrasystemic dynamics that objectively occur in such systems. The adequacy of the proposed mathematical model is proved. © 2022 IEEE.
Patterns of Air Mixture Movement in the Operating Area for the Annular Ejector of Pneumatic Transportation System
(НТУ «Дніпровська політехніка», Дніпро, 2023) Ponomarenko, Serhii M.; Potapchuk, Iryna Yu.; Kabakova, Liudmyla B.; Radchenko, Yurii M.
ENG: Purpose. To establish the regularities of two-phase flow of “gas-solid particles” in the operating area of an annular ejector where the following processes take place: air mixture ejecting, compressed air outflow from the ejector nozzle, air mixture flows mixing in the transport pipeline. In the work, the velocity distribution is also examined for dispersed phase and air phase of air mixture during its loading and accelerating in the transport pipeline of the pneumatic transport system. Methodology. The research is based on the fundamental approaches of mass point dynamics, aerodynamics, the theory of jet flows and iteration methods of numerical solution of equations. Findings. The mechanics of the air mixture flow under the ejection and aerodynamic force in the operating area of an annular ejector and at the beginning of transport pipeline is analyzed using the method of iterations. The impact of air mixture flow in the operating area of an annular ejector on energy performance of the pneumatic transport system is evaluated. Originality. The originality is that, for the first time, the regularities describing two-phase “gas-solid particles” flow at the loading area of the pneumatic transport system with an annular ejector have been obtained. This made it possible to characterize the velocity distribution of the dispersed and air phases of the air mixture during their loading and aerodynamic acceleration in the transport pipeline. Also, an innovative approach to the effectiveness of the use of pipeline pneumatic transport is the assessment of the energy indicators of the use of ejector-type pneumatic transport equipment depending on the rate of compressed air outflow from the ejector. Practical value. The implementation of the results in the modernization of existing and in the creation of new pneumatic transport systems with an annular ejector makes it possible to increase the efficiency of their use in the technological processes of moving dispersed materials at mining and metallurgical enterprises and in other areas of technology.
Phenomena at Three-Phase Electroslag Remelting
(Springer Nature, 2021) Liu, Zhong-li; Medovar, Lev; Stovpchenko, Ganna; Petrenko, Volodymyr; Sybir, Artem; Volchenkov, Yev.
ENG: The electroslag remelting (ESR) process is widely used to produce high-quality ingots and billets for high-alloyed steels and alloys. Both the single-phase and three-phase alternating current diagram with bifilar and monofilar connection are in use for heavy ingot manufacturing. The numerical simulation of the three-phase bifilar circuit for the 120 t three-phase bifilar six-electrode ESR furnace at different variants of electric connection was presented and discussed. At the bifilar diagram of power supply, the geometrical location of electrodes in a mould holds critical importance for performances: the close location of bifilar pair electrodes provides the highest heat productivity, but the equidistant location of electrodes gives a much more uniform heat distribution. The monofilar mulit-electrode diagram of three-phase connection without phase shift shows the most uniform distribution of potential and heat generation as well as a favorable magnetic field that makes this kind the most promising for providing a high quality of heavy ingots.
The Phenomenon of a Mixed Colony: The Case of Lasius Brunneus and Lasius Umbratus (hymenoptera, Formicidae)
(Publishing House “Akademperiodyka”, Kyiv, 2024) Stukalyuk, S.; Radchenko, Yurii M.; Akhmedov, A.; Stelia, V.
ENG: The aim of this work is to study to find out why, in the case of temporary social parasitism, a mixed colony of Lasius brunneus (Latreille, 1798) and Lasius umbratus (Nylander, 1846) exists in this state for many years. In 2023, a mixed colony of L. brunneus (host species) / L. umbratus (temporary social parasite) was discovered in Moldova. This mixed colony is located at the same site where another mixed colony containing Lasius fuliginosus (Latreille, 1798), L. umbratus disappeared in 2017. Video recordings of the intensity of movement of workers of the two species along the trails were made to study the frequency of antennal contacts and to calculate the colony population. Based on the previously used algorithms, it was assumed that the queen oviposition rate of L. umbratus is 1.5 times higher than that of L. niger, while that of L. brunneus is comparable to that of Lasius niger (Linnaeus, 1758). Chi-square test and post-hoc Dunn's test were used for statistical analysis of the data. Mathematical modelling was used to analyse the rate of colony development. Results of the analysis of worker activity on the trail showed that L. brunneus had 11 times more foragers than L. umbratus. A high number of interspecific antennal contacts between workers was recorded. The population of the mixed colony was estimated to be 48.880 L. brunneus and 24.433 L. umbratus workers. Mathematical modelling confirmed the failure of L. brunneus monogyny in a mixed colony and suggested that high L. brunneus abundance is ensured by multiple queens (oligogyny). Probably in 2021, the L. brunneus colony moved to a new habitat, which was invaded by the L. umbratus queen. After the invasion, several L. brunneus queens survived, allowing a mixed colony to exist.
Prediction of Fuel Consumption and Carbon Dioxide Emission when Replacing Gaseous Fuels with Renewable Hydrogen or Their Mixture
(IOP Publishing Ltd, 2024) Gupalo, Olena V.; Yeromin, Oleksandr O.; Kabakova, Liudmyla; Kolienko, Anatoliy; Kirsanov, Mykhailo; Kulikov, Andrii
ENG: The paper is devoted to predicting changes in fuel consumption and carbon dioxide emissions when industrial equipment is converted to heating with renewable hydrogen or a mixture of it with other gaseous fuels, such as natural gas. The authors developed a simplified methodology that is appropriate for assessing changes in the energy consumption of equipment and the environmental impact of fuel replacement at the stage preceding the equipment reconstruction. The peculiarity of the methodology is that it allows the calculation of fuel consumption and carbon dioxide emissions when fuel replacement is accompanied by the implementation of measures aimed at improving the energy efficiency of equipment. The methodology can be used for heating and thermal furnaces in metallurgy and mechanical engineering, units for heat treatment of raw materials in the mining and processing industries, heating devices in the food industry, and water and steam boilers. In the example of replacing natural gas with its mixture with renewable hydrogen of different compositions, it is shown that the calculation error using the proposed methodology in comparison with the results obtained by mathematical modeling of fuel combustion, gas flow and heat transfer in this furnace does not exceed 1.5%.
Research on the Efficiency of Hydrogen Combustion, Alternative and Natural Non-Interchangeable Gases
(The Gas Institute of the National Academy of Sciences of Ukraine, Kyiv, 2025) Kolienko, Anatoliy G.; Sigal, O. I.; Gupalo, Olena V.; Akhmednabiev, Rasul M.
ENG: The results of determining the gas interchangeability criterion are presented. An analysis of the possibility of adapting existing gas combustion plants for the effective and stable use of a wide range of combustible gases is performed. It is shown that even natural gases from different deposits are not always interchangeable. Recommendations are developed that allow the use of even non-interchangeable gases on the same gas combustion equipment by changing the operating settings or slightly changing the design characteristics of the equipment. The results of the study of heat transfer in the combustion space when the composition of combustible gases changes and the associated changes in the emissivity of combustion products are presented. Recommendations are given on the organization of the combustion process of non-interchangeable gases, including by creating mixtures of combustible gases with the provision of the necessary interchangeability criteria. The purpose of the work is to study the possibility of effective combustion of alternative types of artificial and synthetic combustible gases, including hydrogen, as well as non-interchangeable natural gases in existing gas combustion equipment. Study of the properties of combustible gases characteristic of gas distribution systems of Ukraine, and their compliance with the inter-changeability criteria and gas combustion equipment manufactured and supplied for industrial and municipal purposes. The relevance of the issues of ensuring the interchangeability of gases is confirmed by the implementation of regulatory legal acts on the quality indicators of combustible gases and the efficiency of their use in the national legislation of Ukraine. The results of the study provide the possibility of a barrier-free gradual introduction of alternative types of gases and a gradual transition to the combustion of gases with hydrogen content without cardinal changes in the design of existing burners and their operating modes. Bibl. 26, Fig. 2, Tab. 5.
Rheological Properties of Polymer-Polymer Mixtures on Corn Starch Base
(MM Publishing s.r.o., Praha, Czechia, 2022) Rimar, Miroslav; Tretyakoff, Artem; Sukhyy, Kostyantyn M.; Yeromin, Oleksandr O.; Kulikov, Andrii; Fedak, Marcel; Belyanovskaya, Elena; Shunkin, Ihnat; Gupalo, Olena V.; Krenicky, Tibor
ENG: The prospects for the use of polymer-polymer mixtures based on corn starch as alternative thermoplastic materials to polyolefins are considered. Rheological curves have been obtained, which confirm the possibility of processing such mixtures on standard equipment into products. It is shown that the starch content in polymer-polymer mixtures can reach 90 mass percent. Compared to existing biodegradable polymers, plasticized starch-based material is in no way inferior to them in terms of processability. Studies of the mechanical properties of polymer-polymer mixtures based on corn starch have been carried out. The data obtained indicate the possibility of using the developed composites as packaging materials, as well as alternative materials to known bioplastics and synthetic polymers.
Rocket Engine Vacuum Nozzle 3D Printing: Manufacturing, Weight, and Cost Savings
(MDPI AG, Basel, Switzerland, 2025) Alexopoulos, Nikolaos D.; Zeimpekis, Vasileios; Vasileiou, Evangelos; Thomaidis, Nikolaos; Souxes, Theodoros; Lazaridou, Ilona; Lutsyk, Maksym; Vorobev, Roman; Karakash, Evgeniy; Karpovich, Elena; Grydin, Olexandr
ENG: Metallic materials additive manufacturing is extremely challenging nowadays, while aircraft manufacturers are trying to adapt the newly developed technology to produce parts of complex geometry with minimum materials losses. Skyrora is a company focused on the production of several launch vehicles and rockets with the aim of becoming a commercial provider for access to space. One of the Skyrora goals is to develop innovative and long-term solutions for future growth, and, within the Horizon European project “MADE-3D”, aims to improve the rocket propulsion system of the launch vehicle Skyrora XL by exploiting multi-materials during the production phase by additive manufacturing. The main goal of the present investigation is to document the already existing production phases of the “conventional” Skyrora vacuum nozzle printed with Inconel 718 to provide a baseline in terms of weight, manufacturing cost, lead processing time and CO2 equivalent emissions of the under-development multi-material demonstrator.
Selection Criteria of Working Pairs Adsorbent – Adsorbate for Thermal Energy Transformers
(MM Science Journal, Czech Republic, 2022) Rimar, Miroslav; Sukhyy, Kostyantyn M.; Belyanovskaya, Elena; Yeromin, Oleksandr O.; Prokopenko, Elena M.; Kulikov, Andrii; Fedak, Marcel; Frolova, Lilia; Pustovoy, Grigoriy; Kulikova, Olha; Savko, Vitalii
ENG: In the manuscript the main factors that affect the thermal mass of open and closed types of heat storage devices are shown. Also, the main requirements for adsorption modules are given. The calculation procedure has been refined, which includes the determination of heat load, heat of adsorption, adsorbent mass, as well as integral, structural, and specific thermal mass. The specific thermal masses of adsorption heat-accumulating modules of open and closed types were evaluated. The main factors affecting their value are analysed. It is shown that the specific thermal mass of the adsorption heat storage module increases significantly due to the adsorption of water during the discharge of the device. It is shown that it reaches its maximum values at the end of the discharge stage, when the maximum values of adsorption in the cycle are reached. The influence of the design of the heat storage module on the value of the specific thermal mass has been confirmed. It is shown that the maximum values of these changes correspond to the composites containing 80% salt and 20% silica gel, due to the maximum values of the limiting adsorption and the heat of adsorption, which contributes to the lower values of the adsorbent mass, which is required to cover the thermal load. Specific thermal masses of adsorption modules based on "silica gel – sodium sulphate" and "silica gel - sodium acetate" composites are compared. The composition of the composite is 80% sodium sulphate and 20% silica gel, which corresponds to the minimum dimensions of the adsorption module, and therefore the maximum value of the specific thermal mass.
Solid-Phase Polycondensation of Polyethylene Terephthalate with Technologies of Its Reactive Extrusion
(MM Publishing s.r.o., Praha, Czechia, 2023) Rimar, Miroslav; Chervakov, Denys O.; Fedak, Marcel; Kulikov, Andrii; Kulikova, Olha; Sukhyy, Kostyantyn M.; Chervakov, Oleh V.; Bentsionov, Igor; Sverdlikovska, Olga S.; Belyanovskaya, Elena; Yeromin, Oleksandr O.; Prokopenko, Olena M.
ENG: It has been experimentally confirmed that polyethylene terephthalate during its processing into products destruct without carrying out the process of solid-phase polycondensation. The conditions for both primary and secondary polyethylene terephthalate have been determined for carrying out the process of solid-phase polycondensation for its effective reaction extrusion with chain extenders. To confirm the effectiveness of the parameters of the solid-phase polycondensation process of polyethylene terephthalate, its reaction extrusion was carried out with commercially available chain extenders of the diepoxide class. The optimal content of chain extenders of the diepoxide class for changing the complex of physical, mechanical and rheological properties of polyethylene terephthalate modified by them was determined. It allows obtaining materials with an increased by 2.2 times characteristic viscosity.
Structural Analysis of Joints Made of Titanium Alloy TI-6AL-4V and Stainless Steel AISI 321 with Developed Conical Contact Surfaces Obtained by Diffusion Welding
(MDPI, Basel, Switzerland, 2025) Karpovych, Olena; Karpovych, Ivan; Fedosov, Oleksii; Zhumar, Denys; Karakash, Yevhen O.; Rimar, Miroslav; Kizek, Jan; Fedak, Marcel
ENG: The object of this study is welded joints of AISI 321 and Ti-6Al-4V, obtained by diffusion welding on developed conical surfaces. The problem of creating bimetallic joints of AISI 321 and Ti-6Al-4V with developed conical contact surfaces, using diffusion welding through an intermediate Electrolytic Tough Pitch Copper (Cu-ETP) copper layer, was solved. The joints were studied using micro-X-ray spectral analysis, microstructural analysis, and mechanical tests. High mutual diffusion of copper and titanium, along with increased concentrations of Cr and V in copper, was detected. The shear strength of the obtained welded joints is 250 MPa and 235 MPa at 30 min and 15 min, respectively, which is higher than the copper layer’s strength (180 MPa). The obtained results are explained by the dislocation diffusion mechanism in the volume of grains and beyond, due to thermal deformations during welding. Under operating conditions of internal pressure and cryogenic temperatures, the strength of the connection is ensured by the entire two-layer structure, and tightness is ensured by a vacuum-tight diffusion connection. The obtained strength of the connection (250 MPa) is sufficient under the specified operating conditions. Analysis of existing solutions in the literature review indicates that industrial application of technology for manufacturing bimetallic adapters from AISI 321 stainless steel and Ti-6Al-4V titanium alloy is limited to butt joints with small geometric dimensions. Studies of the transition zone structure and diffusion processes in bimetallic joints with developed conical contact surfaces enabled determination of factors affecting joint structure and diffusion coefficients. The obtained bimetallic adapters, made of Ti-6Al-4V titanium alloy and AISI 321 stainless steel, can be used to connect titanium high-pressure vessels with stainless steel pipelines.
Study of the Efficiency of a Gas Turbine on CO2 for the Use of Secondary Heat of Mining Enterprises
(IOP Publishing Ltd, 2025) Kirsanov, Mykhailo; Slobodiannykova, Inna; Gupalo, Olena V.; Privalov, Vladimir
ENG: The mining industry has significant sources of secondary thermal resources with low temperatures of 35°C- 80°C. For their use in the production of additional electricity, it is proposed to use a gas turbine that operates on carbon dioxide (freon R-744) and implements the Rankine cycle. Known detailed tables and model equations for carbon dioxide describe its thermophysical properties. However, they are very complex and challenging to access for inspection. Therefore, this article aims to develop simple analytical expressions for the thermophysical parameters of R-744 for temperatures of 3°C- 80ºC and use them to study effective operation modes of a gas turbine for the use of secondary heat resources of mining enterprises. Mathematical modelling methods, theories of approximation of functions, fundamental laws of gas dynamics and technical thermodynamics were used to achieve the goal. The study resolved the issue of selecting an effective turbine operating mode based on the level of thermodynamic efficiency based on general thermodynamic laws. It was shown that reducing the cooling temperature of R-744 in the condenser from 20°C to 5°C due to the use of mine water increases the thermodynamic efficiency of the Rankine cycle almost twice.
Study of the Efficiency of Using Renewable Hydrogen in Heating Equipment to Reduce Carbon Dioxide Emissions
(IOP Publishing, 2023) Gupalo, Olena V.; Yeromin, Oleksandr O.; Kabakova, Liudmyla; Kulikov, Andrii; Sukhyi, Mykhailo; Romanko, Yaroslav V.
ENG: The results of theoretical study of operation of continuous furnaces heated by natural gas, renewable hydrogen, and their mixture are presented. The furnaces have the same design, but significantly different energy efficiencies due to different heat losses and capability of recuperative fume gas heat utilization system. The measures to reduce heat losses and to increase air temperature for fuel combustion can reduce specific fuel consumption for metal heating and carbon dioxide emissions by 25.8% for natural gas furnaces. For furnaces operating on mixture of natural gas and hydrogen, a greater reduction in carbon dioxide emissions is achieved in furnaces with worse energy efficiency, but with greater fuel consumption for metal heating. The paper shows the possibility of converting a furnace with better energy efficiency indicators to be heated by mixture of natural gas (75%) and hydrogen (25%). The measure reduces the natural gas consumption and carbon dioxide emissions to 9.2% due to the use of hydrogen with specific consumption 13.81 m3 per ton of metal. To ensure the same costs for metal heating when transferring continuous furnaces from natural gas to hydrogen, or their mixture, the ratio of prices for natural gas and hydrogen should not exceed 0.301-0.312.
Study of the Impact of Epoxidized Soybean Oil on the Characteristics of Wood-Polymer Composites
(MDPI, 2025) Kulikov, Andrii; Kryvolapov, Dmytro; Sukhyy, Kostyantyn M.; Yeromin, Oleksandr O.; Fedak, Marcel; Prokopenko, Olena M.; Sukha, Iryna V.; Musaio, Angelo; Hrebik, Tomas
ENG: The effect of epoxidized soybean oil on the operational, technological, and physical and mechanical properties of composites based on high-density recycled polyethylene filled with wood floor was investigated. It has been shown that the introduction of epoxidized soybean oil in the amount of 0.5 wt.% into the wood-polymer composite (WPC) improves the physical, mechanical, and operational properties of the material: the Charpy impact strength (on notched samples) increases from 7.5 kJ/m2 to 20.0 kJ/m2, the bending strength increases from 31.6 MPa to 50.8 MPa, and the coefficient of linear thermal expansion decreases by 15%. With a further increase in the content of epoxidized soybean oil in the composite, its water absorption and technological shrinkage decrease, but its physical and mechanical properties deteriorate.
Synergy of Secondary Energy Resource Utilization and Hydrogen Technology for Reducing the Carbon Footprint of Industrial Thermal Units
(IOP Publishing Ltd, 2026) Kolienko, Anatoliy G.; Gupalo, Olena V.; Akhmednabiev, Rasul M.
ENG: The article presents research results focused on improving energy efficiency and reducing the carbon footprint during pellet burning in rotary kilns. The study includes experimental kiln production, development of its energy balance, analysis of energy loss components, assessment of renewable and non-renewable energy losses, and determination of greenhouse gas emissions. The influence of operating parameters on kiln efficiency was examined, and their optimal values were identified. The thermal potential of secondary energy resources at the pellet burning plant was evaluated. A waste-heat utilization scheme for municipal and domestic heating and hot water supply was proposed. The study also establishes dependencies demonstrating the potential for reducing CO2 emissions when substituting natural gas with a mixture containing reducing hydrogen. Research results on lowering the carbon footprint by burning environmentally neutral biomass are presented, along with practical recommendations. The scientific and applied outcomes of the work enable the development of measures aimed at decarbonization and enhancing the efficiency of rotary kilns used for pellet burning in mining and metallurgical enterprises.
Technological Aspects of Purification and Separation of Hydrogen-Containing Gases Obtained by Gasification of Solid Carbon-Containing Media
(M.S. Poliakov Institute of Geotechnical Mechanics of the National Academy of Sciences of Ukraine, Dnipro, 2025) Shevchenko, Volodymyr; Oparin, Serhii; Davydov, Serhii; Gupalo, Olena V.
ENG: Іn this paper, the subject of study is the processes of purification and separation of hydrogen-containing gases obtained by plasma-chemical gasification of solid carbon-containing media. The work aims to establish the regularities of the influence of technological parameters of hydrogen-containing gases obtained by the gasification of solid carbon-containing media on the specific surfaces of filter partitions, membranes, and adsorbents used for their purification and separation. The graph-analytical research method is used in this work, which consists in finding rational specific surfaces of the processes of purification and separation of hydrogen-containing gases based on the obtained graphical dependencies. Analytical dependencies for calculating the specific surface areas of the filter partition, the membrane, and the adsorbent were established. These dependencies take into account the technological parameters of hydrogen-containing gases and the technological parameters of their separation to produce high-purity hydrogen. Based on the theoretical calculation results, a graphical dependence of the specific surface area of the filter partition on the temperature of hydrogen-containing gases formed during the gasification of solid carbon-containing media and the concentration of solid particles in the gas was obtained. This dependence shows that an increase in the concentration of solid particles and an increase in the temperature of hydrogen-containing gases lead to an increase in the specific surface area of the filter partition. The graphical dependence of the specific surface area of the polyimide membrane on the operating pressure and hydrogen concentration in the permeate and the graphical dependence of the specific surface area of zeolite 13X on the initial hydrogen concentration in the initial gas mixture from 60% to 90% at a final concentration of 99.99% are presented. The paper presents a schematic diagram of purification and separation of hydrogen-containing gases to produce high-purity hydrogen. According to the diagram, the hydrogen-containing gas obtained by the gasification of carbon-containing media is sent for purification from solid particles to a filtration system, from where it is supplied to membrane separation for concentration, and the concentrated hydrogen-containing gas is sent to adsorption separation, where it is separated to produce high-purity hydrogen.
The Use of Secondary Heat Resources during the Accumulation of Compressed Air in Closed Mining Workings
(IOP Publishing Ltd, 2024) Kirsanov, Mykhailo; Slobodiannykova, Inna; Gupalo, Olena V.; Podoliak, Kostiantyn
ENG: The article considers the possibility of energy accumulation in mining workings in order to reduce the consumption of fossil organic fuel by the mining enterprise itself. For this purpose, the authors propose to accumulate compressed air in closed mine workings using secondary heat resources to generate additional electricity. The energy management of mining enterprises can be equipped with freon steam turbines which implement the Rankine thermodynamic cycle to obtain additional electricity from secondary heat. To measure the efficiency of the process, the air mast be compressed isothermally. The compression must be carried out in several stages, and the air must be cooled after each stage. Taking into account the development of energy storage technologies in the form of compressed air in specially prepared closed mining workings, the required air pressure can be from 70 to 90 at. The article assesses the possibility of using a secondary heat resource during air compression at mining enterprises. It is shown that the use of freon steam turbines during the accumulation of compressed air in underground pressure accumulators increases the subsequent production of electricity during the operation of the air turbine by 7.6% during the day.
Вибір початкової теплової потужності нагрівального колодязя в умовах нестабільної роботи підприємства
(Інститут чорної металургії ім. З. І. Некрасова НАН України, Дніпро, 2024) Радченко, Юрій Миколайович; Гупало, Олена В’ячеславівна; Ребриков, О. А.; Штацький, М. О.
UKR: Роботу присвячено пошуку шляхів покращення теплотехнічних показників рекуперативних нагрівальних колодязів при роботі в сучасних умовах, для яких характерна непередбачуваність із забезпеченістю металургійного заводу паливно-енергетичними ресурсами, відсутність сталої виробничої програми, різноманітність виробів, що піддаються тепловій обробці і таке інше. Метою дослідження є визначення раціонального режиму нагрівання зливків (заготовок), який забезпечить мінімум питомої витрати палива при виконанні виробничого замовлення. В якості метода дослідження використано методики розрахунку нагріву металу і показників теплової роботи, які базуються на інженерній теорії нагріву. Інженерна модель розповсюдження теплоти дозволила отримати данні, щодо розподілу температури по перетину заготовки на протязі нагрівання без розв’язання диференційного рівняння теплопровідності, а також розрахувати тривалість окремих періодів нагрівання, теплові втрати робочої камери колодязя до навколишнього середовища. Використання поняття про теплові потужності дозволило визначити основні показники теплової роботи колодязя: продуктивність; питому витрату палива на нагрівання металу; коефіцієнт корисної дії колодязя. В роботі досліджено теплову роботу рекуперативного нагрівального колодязя за типовим режимом нагрівання заготовок: перший період – нагрівання з постійною тепловою потужністю, другий – витримка заготовок при постійній температурі камери колодязя. Визначено, що при нагріванні прямокутних заготовок м’яких марок сталі холодного посаду, мінімум питомої витрати палива на нагрівання металу забезпечує робота колодязя з початковою годинною витратою природного газу 269–398 м3/год. Така теплова потужність колодязя забезпечує прийнятну тривалість нагріву маси металу 29–32 тони на рівні 3,4–4,6 годин. При цьому питома витрата умовного палива складає 48,2 кг/т нагрітого металу.
Вплив збагачення повітря горіння киснем на стійкість кладки доменних повітронагрівачів
(Інститут чорної металургії ім. З. І. Некрасова Національної академії наук України, Дніпро, 2022) Грес, Леонід Петрович; Єрьомін, Олександр Олегович; Гупало, Олена В’ячеславівна
UKR: Статтю присвячено проблемі підвищення ефективності роботи обладнання доменних печей. Нині доменний газ не забезпечує заданих технологічних температур високотемпературних теплових агрегатів (доменні повітронагрівачі, нагрівальні печі, тощо), так як його теплота спалення незначна (3200-3500 кДж/м3). В роботі виконано розрахунково-порівняльний аналіз двох способів підвищення температури горіння: збагачення доменного газу природним (базовий варіант) та збагачення повітря горіння киснем для умов доменних повітронагрівачів с температурою під куполом 1300 та 1350 °С. Показано, що для забезпечення цих температур необхідно доменний газ з теплотою спалення 3228 кДж/м3 збагачувати природним газом (відповідно 4,0 та 5,37 %) або збагачувати повітря горіння киснем (відповідно 29,4 та 32,3 %). При цьому необхідно мати резерв по наявності достатньої кількості технологічного кисню. При збагаченні повітря горіння киснем зменшується питомий вихід продуктів спалення, а для збереження тих же параметрів теплообміну в насадці повітронагрівачів необхідно значно збільшувати витрати доменного газу. При цьому загальні витрати повітря горіння практично не змінюються. Виконані розрахунки довжини факелу, розподілу температур та дійсних і допустимих навантажень по висоті камери горіння доменних повітронагрівачів при забезпеченні температури під куполом 1350 °С за рахунок збагачення доменного газу природним (базовий варіант) та збагачення повітря горіння технологічним киснем. Показано, що при опаленні повітронагрівачів з використанням кисню зменшується довжина факелу і максимум температур зміщується в нижню зону, де більше статичне навантаження на вогнетривку цеглу. Але при цьому допустимі навантаження більші дійсних і таким чином стійкість кладки камери горіння буде забезпечена. При сучасних дефіциті та вартості природного газу його використання є нераціональним. Підігрів компонентів горіння потребує значних капітальних витрат для будівництва комплексу теплообмінників. В деяких випадках на існуючих теплових агрегатах відсутні площі для розміщення теплообмінників. В той же час пристрої для використання кисню прості та дешеві.
До розрахунку вентиляції виробничих приміщень за умов виділення декількох шкідливих речовин
(Запорізький національний університет, 2021) Рижков, Вадим Генієвич; Бєлоконь, Карина Володимирівна; Манідіна, Євгенія Анатоліївна; Троїцька, Олена Олександрівна; Радченко, Юрій Миколайович
UKR: Визначено необхідну продуктивність вентиляційної установки для зменшення концентрації шкідливих речовин за умов одночасного виділення до повітря робочої зони декількох речовин. Розглянуто варіанти речовини різноспрямованої дії; речовини односпрямованої дії з адитивним ефектом; речовини односпрямованої дії з підсилюючим (потенційованим) ефектом; речовини односпрямованої дії з послаблюючим (антагоністичним) ефектом. Запропоновано рівняння, що описують продуктивність вентиляційної установки для зазначених варіантів надходження шкідливих речовин до повітря.
Дослідження впливу інтенсифікації доменного процесу шляхом збільшення витрат дуття на параметри експлуатації системи підводу та нагрівання дуття
(НМетАУ, УДУНТ, Дніпро, 2024) Грес, Леонід Петрович; Гупало, Олена В’ячеславівна; Єрьомін, Олександр Олегович; Радченко, Юрій Миколайович; Суліменко, Сергій Євгенійович
UKR: Метою роботи є дослідження впливу збільшення витрат дуття на параметри експлуатації системи подачі та нагрівання дуття для умов доменної печі корисним об’ємом 1754 м3. Методика. Для виконання досліджень використано чисельно-розрахунковий метод, який передбачає виконання розрахунків спалення палива, тепломасообміну та газодинаміки з визначенням експлуатаційних параметрів системи подачі та нагрівання дуття на дільницях «турбоповітродувка – блок повітронагрівачів – тракт гарячого дуття – доменна піч». Результати. Визначено, що забезпечення температури під куполом повітронагрівачів 1350 °С потребує збагачення доменного газу природним до вмісту природного газу в природно-доменній суміші 5,6 %. Нагрівання збільшеної на 18,5 % витрати дуття потребує підвищення теплової потужності повітронагрівачів до максимально можливої і призводить до зниження температури нагріву дуття на 30 °С. При цьому теплові втрати трубопроводу гарячого дуття на ділянці «повітронагрівачі-фурми доменної печі» майже не змінюються, в той час як витрати димових газів та втрати їх тиску в димовому тракті повітронагрівачів суттєво зростають. Оскільки евакуація димових газів із повітронагрівачів відбувається в основному за рахунок тиску компонентів спалення, рекомендовано використання централізованої подачі повітря з вентилятором більшої продуктивності. Наукова новизна роботи полягає у виявленому взаємозв’язку між витратами дуття та експлуатаційними параметрами системи його нагрівання та підводу до доменної печі. До практичної значущості роботи слід віднести розроблені рекомендації щодо забезпечення експлуатації системи підводу та нагрівання дуття при збільшенні його витрат.
Дослідження ефективності використання суміші повітря, димових газів та технологічного кисню в якості окиснювача при опаленні доменних повітронагрівачів
(Інститут чорної металургії ім. З. І. Некрасова НАН України, Дніпро, 2023) Петряков, Миколай Володимирович; Грес, Леонід Петрович; Гупало, Олена В’ячеславівна; Верещак, Віктор Іванович; Єрьомін, Олександр Олегович; Григор’єв, Антон Сергійович
UKR: Підвищення температури нагріву доменного дуття є одним із відомих способів економії коксу при виробництві чавуну. Для нагрівання дуття використовуються повітронагрівачі, які зазвичай опалюються доменним газом. Оскільки склад і теплота згоряння доменного газу недостатні для досягнення температури горіння доменного газу, яка забезпечує достатнє підігрівання насадок повітронагрівачів для нагрівання дуття на рівні 1160-1230 °С, використовуються різні методи збільшення температури горіння доменного газу. В даній роботі досліджено ефективність застосування одного з таких методів – використання в якості окиснювача для спалення доменного газу в повітронагрівачах суміші повітря, димових газів та технологічного кисню. Для підготовки суміші блок повітронагрівачів оснащується додатковим обладнанням: теплогенератором для спалювання доменного газу с атмосферним повітрям, та змішувачем, в якому високотемпературні димові гази, що утворюються при спалювання палива в теплогенераторі, змішуються з атмосферним повітрям та технологічним киснем з утворенням повітро-димової суміші у складі якої міститься 21 % кисню. Використання підготованої таким чином суміші збільшує температуру горіння палива в повітронагрівачах і забезпечує підвищення температури нагріву насадки, що в свою чергу сприяє підвищенню температури нагріву доменного дуття. Результати роботи містять порівняння ефективності даного методу з іншими відомими методами збільшення температури горіння палива в повітронагрівачах: збагачення доменного газу природнім, підігрів компонентів горіння перед спалюванням палива в повітронагрівачах; збагачення повітря горіння киснем. В роботі показано, що використання повітро-димової суміші при інших рівних умовах, має деякі переваги у порівнянні з іншими методами, а саме не призводить до суттєвого зниження виходу димових газів, які утворюються при спалюванні палива в повітронагрівачах, що не погіршує теплообмін в насадці теплообмінників, а також підвищує повноту використання власних енергоресурсів підприємства (доменного газу і технологічного кисню) при наявності їх залишків. До недоліків використання повітро-димової суміші слід віднести можливість утворення вибухонебезпечної суміші під час змішування технологічного кисню з високотемпературними продуктами згоряння палива, які можуть містити угарний газ. Тому питання безпечної реалізації змішування димових газів, кисню і атмосферного повітря потребують подальшого дослідження і детальної розробки конструкції змішувача.