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E-Journal №1(65)2025

"PROBLEMS of the REGIONAL ENERGETICS (https://doi.org/10.52254/1857-0070.2025.2-66)"

CONTENTS

1	Improving the Efficiency of an Energy System with an Internal Combustion Engine Using a Solid Oxide Fuel Cell Authors: 1Mytrofanov O., 1Proskurin A., 2Kong W. 1Admiral Makarov National University of Shipbuilding Mykolaiv, Ukraine 2 Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, China
	Abstract: This paper explores the possibility of using a solid oxide fuel cell as part of an energy system with an internal combustion engine running on bioethanol, incorporating thermochemical waste gas heat recovery. The main goal of the research is to determine the efficiency of energy con-version in energy systems with deep waste gas heat recovery. To achieve this goal, the following tasks were set: based on experimental studies of a spark-ignition engine running on bioethanol, determine the parameters of the process for synthesizing gas through thermochemical conver-sion; theoretically investigate the efficiency of using a solid oxide fuel cell in combination with a bioethanol thermochemical conversion reactor. The most significant result is the determination of the volt-ampere characteristic of the solid oxide fuel cell and the identification of the poten-tial heat recovery capacity of the internal combustion engine exhaust gases through deep heat recovery. The significance of the obtained results lies in the theoretical and experimental valida-tion of efficient energy conversion of synthesis gas in a solid oxide fuel cell, achieving a high thermodynamic efficiency of the cell (0.95–0.75). The proposed energy system configuration, based on an internal combustion engine running on bioethanol with thermochemical waste heat recovery, allows for a 6.5% increase in the overall system power output. This contributes to re-duced fuel consumption and improved environmental performance. The research findings can be applied in the design and development of highly efficient energy systems with internal com-bustion engines for various applications.
	Keywords: solid oxide fuel cell, internal combustion engine, energy system, alternative fuel, synthesis gas, heat recovery. DOI: https://doi.org/10.52254/1857-0070.2025.2-66.01
2	Mechanical Power of Induction Motors with Non-sinusoidal Power Supply Authors: 1Kovalov V., 2Kovalova Yu. 1National Aerospace University of Ukraine "Kharkiv Aviation Institut" 2 O.M. Beketov National University of Urban Economy in Kharkiv Kharkiv, Ukraine
	Abstract: When induction motors are powered by solid-state voltage and frequency converters, the torque on the shaft is created by the first harmonic of the current, and the higher harmonics of the cur-rent only create losses in the stator winding. The purpose of the work is to develop a methodolo-gy for determining the permissible mechanical load of asynchronous motors at non-sinusoidal currents. To achieve this goal, it is necessary to determine the influence on the mechanical pow-er of the motor of higher current harmonics, the effective values of which depend on the control parameters of semiconductor voltage and frequency converters. For quantitative assessment of their influence on mechanical power, it is proposed using the current harmonic coefficient as a generalized parameter as the ratio of the sum of the effective values of higher current harmonics to the effective value of the first harmonic. As a result of researches, the expression for calcula-tion of the coefficient of admissible mechanical load of the motor concerning a nominal value taking into account the coefficient of current harmonics is received. Scientific novelty: for the first time, the analytical expression for determining the coefficient of permissible mechanical load of induction motors powered by semiconductor converters of voltage and frequency using the current harmonic coefficient is obtained. Practical significance: the proposed methodology allows checking the selected induction motor for heating when supplied from semiconductor converters of voltage and frequency for a given mechanical power of the working mechanism.
	Keywords: induction motor, mechanical power, harmonics coefficient, permissible loading coefficient. DOI: https://doi.org/10.52254/1857-0070.2025.2-66.02
3	Integrated Renewable Energy System Using High Gain Interleaved Boost Converter with Modified Cheetah Optimization Based Adaptive PI-Controller Authors: Sharda P., Himanshu S., Pal R. K. Department of Electrical Engineering, Medicaps University, Indore, Madhya Pradesh, India
	Abstract: This study introduces an innovative strategy to boost the uptake of Electric Vehicles (EVs) while curbing greenhouse gas emissions. Addressing the primary limitation of EVs - their reliance on energy storage - entails integrating a high-performance brushless DC (BLDC) motor renowned for its swift dynamic response and efficiency. The main objective of the study is to merge Photovoltaic (PV) energy generation with a bidirectional grid connection for powering the BLDC motor effectively. This objective is achieved by the introduction of a High Gain Interleaved Boost Converter (HGIBC) for enhancing voltage-gain ratio and system adaptability of the PV system. A novel Modified Cheetah Optimization (MCO)-based Proportional Integral (PI) controller ensures precise control signal generation for the converter. The AC supply to the motor is facilitated by a 3-phase Voltage Source Inverter (VSI), with speed regulation achieved through a PI controller. Simultaneously, the Bidirectional single phase grid augmented with an adaptive PI controller and a battery system with bidirectional converter distribute power supply to the BLDC motor fed EV during in sufficient power supply from PV system due to its ecological changes. Moreover, to validate the importance of proposed system, MATLAB/Simulink is utilized. The most important results are the proposed HGIBC exhibits a higher voltage gain when compared to other existing Boost converters and generates an increased efficiency of 97%. Also, with the optimized PI controller a steady converter output of 1000V is achieved at 0.35s which indicates a reduced settling time. Also, the proposed work generates a reduced simulation THD value of 1.21%. The significance of the obtained results lies in the delivering of high converter efficiency, improved power quality and reliable performance of BLDC motor system.
	Keywords: electric vehicles, BLDC motor, photovoltaic, high gain interleaved boost converter, Modified Cheetah optimized PI controller, VSI, battery system, MATLAB/Simulink. DOI: https://doi.org/10.52254/1857-0070.2025.2-66.03
4	Investigation of Dependence of Brightness-Structural Features of Images Generated by the Vision System on Navigation Parameters of Unmanned Aerial Vehicles and their Use for Selection the Object of Reference Authors: 1Sotnikov O., 2Vlasov I., 3Pavlov Ya., 4Morin O., 5Kizian R., 6Lukyanova V. 1 Kharkiv National Air Force University named after Ivan Kozhedub, Kharkiv, Ukraine 2National University of Defense, Kyiv, Ukraine 3National Academy of the National Guard of Ukraine, Kharkiv, Ukraine 4Institute of Problems on Education of the National Academy of Educational Sciences of Ukraine 5Kyiv Institute of the National Guard of Ukraine, Kyiv, Ukraine 6Kharkiv National University of Radio Electronics, Kharkiv, Ukraine
	Abstract: The aim of the article is to substantiate the use of brightness-structural features of images to select a reference object. This goal is achieved by studying the dependence of brightness-structural features of images on the sighting geometry. The solution to the first problem is based on the study of the brightness properties of images for their subsequent segmentation. The study was performed in the MATLAB software environment. The influence of sighting geometry on the distribution of image brightness was determined for sighting angles from -30˚ to -60 ˚ and altitudes from 500 to 1500 meters. The solution to the second problem is based on the study of the structural properties of images segmented by brightness. The solution to the third problem is to assess the efficiency of selecting a reference object on a segmented image using structural-brightness features. The most significant result is the substantiation of the use of brightness-structural features of images and the definition of the conditions for their use to select a reference object. The significance of the results lies in the analysis of brightness-structural features of images with different object content from the sighting geometry. The novelty of the work lies in the development of the procedure for forming current images and the decision function using the brightness-structural features of images. The difference from known works is the use of a new set of informative features in the formation of a segmented image, which is necessary for making a decision on the selection of a reference object.
	Keywords: brightness-structural features of images, unmanned aerial vehicle, navigation parameters, reference object. DOI: https://doi.org/10.52254/1857-0070.2025.2-66.04
5	Comparison of the Combined Shielding Effectiveness Based on Experimental Studies of Overhead Power Lines Magnetic Field 3D Model Authors: Bovdui I.V. Anatolii Pidhornyi Institute of Power Machines and Systems of the National Academy of Sciences of Ukraine, Kharkiv, Ukraine
	Abstract: The aim of the work is an experimental study of the efficiency of combined shielding of the magnetic field generated by transmission lines (HVPL) with single-circuit and triangular arrangements of wires and double-circuit transmission lines with a "Barrel" type of wire arrangement using an active shielding system and passive shields made in the form of solid, or multi-loop, shields. To achieve this goal, the structure of combined shields was determined, which consist of a double-loop active shield and solid or multi-loop shields. The developed combined shields provide increased efficiency in reducing the level of industrial frequency (MF) magnetic field. Designing combined shields is reduced to solving vector games in which the cost vector of the game is calculated based on solutions to Maxwell's equations in a quasi-stationary approximation using the COMSOL Multiphysics software package. The solution to these vector games is calculated based on the "particle swarm" optimization algorithms from Pareto-optimal solutions, taking into account binary preference relations. The most important results are the calculated values of the spatial arrangement coordinates of two compensation windings of the active shielding system and the values of currents and phases in these windings, as well as the parameters of solid and multi-loop passive screens, which made it possible to increase the efficiency of MF shielding inside residential buildings from that generated by single-circuit HVPL with the triangular wire arrangement and double-circuit HVPL with the "Barrel" type conductor arrangement. The significance of the obtained results is that practical recommendations are given for the justified choice of the spatial arrangement of two shielding windings of the robust active shielding system, as well as the parameters of solid and multi-loop passive screens for combined shielding systems of MF generated inside residential buildings by single-circuit HVPL with triangular wire arrangement and double-circuit HVPL with the "Barrel" type conductor arrangement. The possibility of reducing the induction level of the initial MF to the level of sanitary standards is shown.
	Keywords: overhead power lines, magnetic field, combined shielding, experimental studies. DOI: https://doi.org/10.52254/1857-0070.2025.2-66.05
6	Improvement of Energy Efficiency of Dehydration Processes in the Conditions of Selective Supply of Electromagnetic Energy Authors: Burdo O.G., Levitsky A.P., Sirotyuk I.V., Burdo A.K., Kepin N.I., Petrovsky V.V., Yevtushenko I.N. Odesa National University of Technology, Odesa, Ukraine
	Abstract: An analysis of conventional dehydration processes used in food technologies—evaporation and drying—has been conducted, and their key challenges have been identified. The global research experience in dehydration technologies based on innovative microwave energy sources is reviewed. The studies carried out indicate that dehydration in an electromagnetic field holds clear promise both in terms of reducing energy consumption and improving the quality of the final product. At the same time, the existing research has been conducted using laboratory-scale setups; comprehensive studies and engineering design methods for electrodynamic—type equipment are lacking. The aim of this work is to develop the scientific foundations of dehydration processes under conditions of selective electromagnetic energy supply, to formulate design methods for continuous—flow dehydrators, and to create and test an experimental prototype of an electrodynamic dehydrator. To achieve the stated goal, the authors have synthesized previous research—where they hold priority—and formulated a hypothesis for the creation of apparatuses that address the scientific and technical contradictions inherent in traditional technologies. It is demonstrated that, under selective energy supply conditions, solutions can be concentrated within a single unit. The paper analyzes transformation schemes within the dehydrator, a parametric model, and the design of the experimental prototype. Results on the quality of obtained concentrates are provided. The most important outcome of the work is the development of theoretical foundations for dehydration in a microwave field, yielding high-quality concentrates. The significance of the study lies in the creation of an energy—efficient electrodynamic unit that replaces conventional evaporators and dryers.
	Keywords: dehydration processes, microwave field, electrodynamic systems, evaporation, drying, production technological equipment, nutrition technologies. DOI: https://doi.org/10.52254/1857-0070.2025.2-66.06
7	Straw Pellets Burning in a Fixed Bed with Low Ash Agglomeration Authors: Zhovmir M.M. Institute of Renewable Energy of the National Academy of Sciences of Ukraine, Kyiv, Ukraine
	Abstract: Melting of the straw pellets’ ash leads to bed agglomeration with incomplete burning out and even to burning extinguishing. The aims of the work are to study the ash agglomeration during the combustion of straw pellets in a fixed bed at different primary air velocities, which differs by being carried out at various thicknesses of the pellets bed, and to substantiate the mode of burning with minimized ash agglomeration. The aims are achieved by: batch burning of straw pellets with recording bed temperatures; determining the mass fraction of agglomerated ash; determining the ash fusibility temperatures; analyzing the chemical composition of ash and calculating the agglomeration indices; determining energy loss because of incomplete carbon burnout. The most important results are: experimental evidence that decreasing the primary air velocity, combined with lowering the pellets bed thickness, resulted in lower maximal temperatures in the bed and decreased bottom ash agglomeration; when maximal bed temperature decreased the chemical composition of bottom ash changed with ash indices shifting to lower slagging and agglomeration. The practical significance of the obtained results is that at maximal bed temperatures ranging from 1061 to 915°C, the content of agglomerated bottom ash, having initial deformation temperatures of 1065–1045°C, was 0.03 of ash mass. This is a so-called low-temperature mode of burning where the maximal temperature in the burning bed is lower than the initial deformation temperature of the formed bottom ash, thus preventing its melting and agglomeration, and is recommended for straw pellets combustion in a continuously operated burner with acceptable energy loss because of incomplete carbon burnout.
	Keywords: straw pellets, bottom ash, ash composition, ash melting, ash fusibility, initial deformation temperature, ash agglomeration. DOI: https://doi.org/10.52254/1857-0070.2025.2-66.07
8	Method for Estimating the Bandwidth Capacity of a Steganographic Communication Channel Authors: 1Bobok I.I., 2Kobozieva A.A., 3Laptiev O.A., 4Savchenko V.A., 5Salii A.G., 5Kurtseitov T.L. 1Odesа Polytechnic National University, Odesa, Ukraine 2Odesa National Maritime University, Odesa, Ukraine 3Taras Shevchenko National University of Kyiv, Kyiv, Ukraine 4State University of Information and Communication Technologies, Kyiv, Ukraine 5National Defense University of Ukraine, Kyiv, Ukraine
	Abstract: Ensuring information security in critical infrastructure, particularly in the energy sector, is highly relevant today. Steganographic methods are among the most effective for information protec-tion, but they can also be misused for unauthorized extraction of classified data. This makes ef-fective steganalysis crucial. One key task of steganalysis is estimating the bandwidth capacity of a covert communication channel, which remains unsolved, especially for digital video or image sets under low-bandwidth conditions. The main objectives of the study are to develop a ste-ganalytic method for estimating the bandwidth capacity of a covert channel using an improved approach to analyzing information systems. The method is designed to be effective in low-bandwidth scenarios and independent of container format (lossy or lossless). To achieve these objectives, the study examines how singular value matrix perturbations of video frames/images depend on frame sequence after steganographic embedding. It also defines conditions for the disruption of the stabilization region of singular values, previously identified by the authors in original content. The most important results of this research include the development of an algo-rithmic implementation of the proposed steganalytic method, which demonstrates high efficien-cy under low-bandwidth conditions (≤25%) and is independent of the container format. Testing of the algorithm revealed no cases of incorrect bandwidth estimation. The significance of the obtained results lies in the demonstrated feasibility of adapting the proposed steganalytic method to assess other types of perturbation effects beyond steganographic embedding. This is particularly relevant for digital content integrity verification and forensic analysis.
	Keywords: steganalysis, steganographic channel capacity, digital video, digital image, general approach to analyzing the state of information systems, singular value. DOI: https://doi.org/10.52254/1857-0070.2025.2-66.08
9	The Use of Straw Pellets with the Addition of Crude Glycerin for the Intensification of Biogas Production during the Anaerobic Fermentation of Cow Manure Authors: Polishchuk V., Shvorov S., Voitiuk V., Khmelovskyi V., Titova L., Yeremenko O., Zubok T., Valiev T. National University of Life and Environmental Sciences of Ukraine, Kyiv, Ukraine
	Abstract: Cow manure is a good substrate for producing biogas, since it already contains methanogens. Almost its only drawback is the low productivity of biogas output. The disadvantage of cattle manure is its low biogas yield, to increase which it is proposed to add granulated straw with the addition of crude glycerin. The aim of the work is to increase the biogas yield by adding straw granules containing crude glycerin to the main substrate based on cattle manure. To achieve this goal, the following tasks need to be solved: to determine the biogas and methane yield during methane mono-fermentation of cattle manure and combined methane fermentation of cattle manure with straw granules containing crude glycerin; using a mathematical model, to predict the cumulative biogas and methane yield during methane mono-fermentation of cattle manure and combined methane fermentation of cattle manure with straw granules containing crude glycerin. The novelty of the chosen topic is that for the combined methane fermentation of cattle manure and straw pellets with crude glycerin, the cumulative yield of biogas and methane was determined, which for 30 days is 293.7 l/kg of dry organic matter (DOM) and 143.5 l/kg of DOM, respectively. The significance of the results is that the results of the research can be used in industrial biogas plants in a quasi-continuous loading mode. In this case, the predicted methane yield will be 0.449 l/h⋅kg of DOM, which is higher than with mono-fermentation of cow manure, which is 0.365 l/h⋅kg of DOM.
	Keywords: biogas, methane, methane digestion, biogas plant, fermenter, straw pellets, crude glycerol, cow manure, methanogens. DOI: https://doi.org/10.52254/1857-0070.2025.2-66.09
10	Wind Turbine’s Aerodynamic Multiplication Parameters for Different Types of Generators Authors: Strunkin H.N. Research laboratory "Industrial Electronics", Engineering Institute of Zaporizhzhia National University, LLC “Pluton IC”. Zaporizhzhja, Ukraine
	Abstract: Energy transition is impossible without wind power development. The need for a mechanical multiplier to match the speeds of a wind turbine and generator leads to deterioration of the tech-nical system's indicators. Refusal of a mechanical multiplier is possible with the help of aerody-namic multiplication. Despite the presence of work in this direction, there is still no coverage of the influence of aerodynamic multiplication parameters on the choice of a generator. Main objectives of the study – analyze the requirements that a generator makes to wind turbine’s aero-dynamic multiplication parameters. How these objectives were achieved: construction of regression models for existing wind turbines describing the dependence of the rotor diameter and the angular velocity of the wind turbine on the power; optimization of secondary wind velocity by the power of the wind turbine; proof of maximum of the secondary wind does not depend on the fixing radius of the secondary wind turbine; obtaining the dependence of the fixing radius of the secondary wind turbine on the angular velocity of the generator. The most important results are the calculation of the upper power limit, at which the use of aerodynamic multiplication is appropriate; obtaining recommendations for the selection of the secondary wind turbine fixing radius for different types of generators. The significance of the obtained results is in the systematization of experience foundations for selection of aerodynamic multiplication parameters; the formation of tasks for the optimization of wind power plant parameters according to strength parameters and the development of special generators.
	Keywords: aerodynamic multiplication, regression model, secondary wind flow, fixing radius, wind turbine power, angular velocity. DOI: https://doi.org/10.52254/1857-0070.2025.2-66.10
11	Reducing Energy Costs for Gas Preheating through Gas-Dynamic Stratification in the Leontiev Tube Authors: Kovalnogov V.N., Rudnik R.S., Matveev A.F. Ulyanovsk State Technical University Ulyanovsk, Russian Federation
	Abstract: The main objectives of this study are to reduce the energy consumption for gas preheating and improve the efficiency of compression systems using gas-dynamic temperature stratification in the Leontiev tube. In order to achieve these objectives, the following tasks were carried out: a numerical analysis was performed using the finite volume method (RANS) and the k–ω SST tur-bulence model, and the Navier–Stokes equations were discretized on a multi-block mesh of 3 million cells, with local refinement in the nozzle and separation wall zones. Particular attention was paid to the influence of the inlet nozzle geometry on the temperature distribution, flow ve-locity, and heat transfer through the separation wall, as well as the stability of the flow under different pressure differentials. The most significant results include the superior performance of the bell-shaped nozzle design over the annular one: modelling showed a 60 K temperature dif-ference between supersonic and subsonic flows (110.5% higher than the baseline), a 20–25 K increase in hot flow temperature at the outlet, stable flow without pressure surges, and effective gas heating prior to throttling using pipeline pressure drops, preventing condensation and reduc-ing costs. The significance of these results lies in demonstrating the superiority of machine-free energy separation technologies, such as gas-dynamic stratification in the Leontiev tube with a bell-shaped nozzle, over traditional energy-intensive heating methods, leading to more rational resource utilization and reduced environmental impact under strict energy efficiency and ecolog-ical standards.
	Keywords: gas dynamics, compression systems, heat transfer, numerical modeling, design optimization, energy separation, Leontiev tube, turbulence. DOI: https://doi.org/10.52254/1857-0070.2025.2-66.11
12	The Influence of Laminarizers on the Turbulent Boundary Layer and Prediction of Effective Flow Conditions around Surfaces Authors: Chukalin A.V., Kovalnogov V.N., Sherkunov V.V., Savelov O.V. Laboratory of Inter-Disciplinary Problems in Energy Production, Ulyanovsk State Technical University, Ulyanovsk, Russian Federation
	Abstract: The development of effective methods for boundary layer laminarization is a fundamental task for the efficient and reliable operation of power equipment. The main objective of the work is to study the effect of a damping surface on flows in the boundary layer occurring in complex gas-dynamic conditions and to implement a method for predicting effective conditions for flow past damping surfaces. The implementation of the mathematical model allows performing calcula-tions and creating a database for analyzing and selecting the most effective conditions for using a damping surface. To achieve the set goal, the following tasks were solved: development of a damping surface, complex experimental studies of wall flows on models with a damping sur-face, systematization of experimental data results, development of an original semi-empirical model of turbulent transfer in the boundary layer on a damping surface with its subsequent im-plementation in a software package for studying the boundary layer in a wide range of gas-dynamic conditions with external intense effects. The most important result of the work is the development of a method for laminarization of the boundary layer by means of a damping sur-face, the operating principle of which is to suppress turbulent pulsations of velocity and pressure near the streamlined surface. The significance of the obtained results lies in the proposal of a method for laminarization of the turbulent boundary layer and a technique for predicting effec-tive conditions of flow past surfaces, to reduce turbulent friction and increase the efficiency of surface cooling.
	Keywords: boundary layer, turbulence, laminarization, modeling, heat and mass transfer, gas dynamics. DOI: https://doi.org/10.52254/1857-0070.2025.2-66.12
13	Enhancing the Energy Efficiency of the Combined Forging Operations of Upsetting and Drawing out Authors: Kolisnyk K.D., Chukhlib V.L. National Technical University «Kharkiv Polytechnic Institute» Kharkiv, Ukraine
	Abstract: The study investigates the influence of upsetting and drawing out forging parameters on the quality of hook forging and the energy efficiency of these processes. The quality indicators of forged hooks include uneven strain distribution, which leads to a non-uniform distribution of the mechanical properties of the product. The forging technology of hooks was analyzed, and it was determined that the main technological forging operations causing uneven deformation distribution are the sequential upsetting and drawing out processes. Since the influence of specific parameters of these operations remains insufficiently studied, this research was conducted to compare and determine the effect of upsetting and drawing out parameters when performed sequentially in order to improve the mechanical properties of forged hook metal. The modeling was carried out using the QForm engineering software package. To study the distribution of the mechanical properties of the metal, a method for assessing deformation non-uniformity in the cross-section of the forging was applied. Indicators of plastic deformation were considered in one section along the height for upsetting and in one section along the length for drawing out. Additionally, graphs of the deformation non-uniformity coefficient distribution during upsetting and drawing out of the billets were constructed. It was determined that the optimal shape factor for upsetting is h/D = 2. In this case, deformation non-uniformity is reduced by 60%. For drawing out with prior upsetting, the optimal shape factor is also h/D=2 with a strain degree of ℇ=20%. The analysis showed that deformation non-uniformity is reduced by 54%. Additionally, the energy efficiency of the processes was analyzed: with h/D=2, energy consumption during upsetting is reduced by 20–25%, and for drawing with h/D=2 and ℇ=20%, the third pass (2.838 MN) is the least energy-intensive, providing an energy saving of 25–30%.
	Keywords: hook, forging, upsetting, drawing out, shape factor, degree of deformation, quality, energy efficiency. DOI: https://doi.org/10.52254/1857-0070.2025.2-66-13
14	Active Power Distribution System between Phases of the Transformer’s Converter Authors: Morozov P. V., Morozov Yu. V. Novosibirsk State Technical University, Novosibirsk, Russian Federation
	Abstract: The paper proposes the system that distributes automatically active power between phases at the secondary side of a traction transformer-based converter. The application area for this system is ac railways with big volumes of delivered items. The purpose of the paper is to develop and investigate the equivalent circuit of the proposed system as an electrical complex for automatic power distribution between phases of the transformer-based converter with phases of the rail-way traction power system at the secondary side. The equivalent circuit of the mentioned above electrical complex is stated. The expressions describing the process of automatic distribution of active power are based on the instantaneous power theory. It is shown how the unbalance factor and total harmonic distortion depend on the number of switching element cells at each phase and pulse-width modulation switching frequency. As it follows from the simulation, the pro-posed electrical complex should consist of eight cells of switching elements connected to each phase to provide values of the unbalance factor and total harmonic distortion no more than two percent. The pulse-width modulation phase has to be a multiple of 45 degrees. The most im-portant result is the proposed equivalent circuit of the system for active power distribution be-tween the transformer-based converter phases at its secondary side, distinguished by the capabil-ity of getting the optimal number of switching element cells by simulation based on the instantaneous power theory. The results relevance include improvement of the electric power quality indicators such as unbalance and total harmonic distortion and decrease of wear factor values for transformers and transmission lines.
	Keywords: transformer-based converter, big volumes of goods delivery, ac railways, unbalance, total harmonic distortion, pulse-width modulation, active power, switching element. DOI: https://doi.org/10.52254/1857-0070.2025.2-66.14
15	Features of Combustion of Water-fuel Emulsions with Different Methods of Introducing Water into the Combustion Zone Authors: Kolbasenko O.V., Dymo B.V., Anastasenko S.M., Shostak O. V. Admiral Makarov National University of Shipbuilding Мykolaiv, Ukraine
	Abstract: The main purpose of the article is to conduct research on combustion quality and determine nitrogen oxide concentrations for various methods of introducing water into the combustion chamber zone. To achieve the goal, the experimental study of combustion features was carried out on a combustion chamber model when supplying unwatered fuel oil of the M40 type, fuel oil, and water vapour in the amount equivalent to 30% of the mass of the fuel mixture, and two types of water-fuel emulsion with a water content of 15% and 30%. Values of gas temperature, concentration CO_2,H_2 та CH_4, as well as nitrogen oxides and (NO_2:NO) ratio were measured along the length of the combustion chamber. Studies have shown a reduction in nitrogen oxide emissions and an increase in the (NO_2:NO) ratio to 0,330 when supplying a water-fuel emulsion with a water content of up to 30%. This increases absorption properties of sulfuric acid in flue gases and reduces the intensity of low-temperature corrosion. When using a water-fuel emulsion of such a composition, it becomes possible to use condensation surfaces of boilers with a significant increase in their efficiency of up to 5…9% Experimental studies have also shown that additional generation Н_2, significant thermal decomposition effect NO_x NO_x, generation of acoustic vibrations and microexplosions take place. This indicates that water-fuel emulsions are a special type of fuel, qualitatively and quantitatively changing the physicochemical processes of combustion. The most important results, constituting the significance of the research, are the experimental proofs of the advantage of using an innovative technology for preparing water-fuel emulsion, based on intense cavitation treatment of the fuel mixed with water obtained from an electrodialysis unit. This achieves better emulsion combustion performance compared to other methods of its preparation and the introduction of water into the combustion zone.
	Keywords: water in the combustion zone, water fuel emulsion, microexplosions, thermal decomposition, acoustic vibrations. DOI: https://doi.org/10.52254/1857-0070.2025.2-66.15
16	Assessment of the Influence of Design Parameters of a Pneumatic Drive on the Energy Efficiency of the Working Process Authors: Krutikov G., Strizhak M. National Technical University «Kharkiv Polytechnic Institute» Kharkiv, Ukraine
	Abstract: The aim of the study is to assess the impact of the pneumatic system structure and the choice of control algorithm for pneumatic distributors on the feasibility of implementing an energy-saving operating mode. This mode involves converting the kinetic energy of moving actuator masses into the potential energy of compressed air, with subsequent recuperation into the network. The objective is achieved by solving the following tasks: implementing pulse and relay control algorithms for various pneumatic drive configurations; investigating the influence of system parameters and control algorithms on the transient process shape and the ability to recuperate energy into the network during braking. During the course of these tasks, it was found that the shape of the transient process is influenced by the braking start moment and its duration, as well as the initial pressure level in the working (piston) chamber. The most significant result is the identification of pneumatic drive structural schemes and control algorithms that enable energy recuperation into the main line during braking, thereby providing a positive energy-saving effect. An analytical description of the sources of compressed air savings during drive operation is also provided. The significance of the results lies in the fact that the obtained schemes, which include braking by altering the connection structure of the pneumatic cylinder chambers, make it possible to implement an energy-saving operating mode. In this mode, the kinetic energy of moving actuator masses is converted into the potential energy of compressed air and is recuperated into the network. This enables further use of the recovered energy, enhancing the overall energy efficiency of the system.
	Keywords: pneumatic drive, control algorithm, switching, energy recovery, transient process. DOI: https://doi.org/10.52254/1857-0070.2025.2-66.16