ISSN 2223-0858 (Online) Subject: theoretical and applied sciences, technology and industry in the field of energy and automation Year established: 2009 Founders: National University of Life and Environmental Sciences of Ukraine Published 4 times a year Media identifier R40-02287. The National Council of Television and Radio Broadcasting of Ukraine Decision No. 1796 of 21 December 2023, protocol No. 31. Speciality DAK: Technical Sciences Languages of the publication: Ukrainian, English Address: Heroiv Oborony st., 12, Kyiv-03041, Ukraine Phone: +38 044 527 85 22 Indexed in the following international scientometric databases: Google Scholar AGRIS MIAR BASE ResearchBib DRJI Ulrichsweb
Національний університет біоресурсів і природокористування України
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Luminescent labeling of leaves for remote monitoring of plants
Luminescent markers are attracting increasing attention as a means of monitoring plant health due to the development of modern technologies for collecting, processing, and storing data necessary for precision agriculture. The combination of optical characteristics (reflection and emission of light) of markers (phosphors) and plant leaves allows remote monitoring, which contributes to the automation of the plant growing process. At the same time, the choice of the phosphor and the method of its application to the plant remains a relevant area of scientific research. In this work the results of the study of optical characteristics such as: diffuse reflection, photoluminescence (PL), and PL excitation spectra of leaves "before" and "after" the application of suspensions of two types: phosphor + water and phosphor + water + PVA, where the phosphor was SrAl2O4:Eu,Dy powder, have been analyzed. It was found that the application of suspensions of both types increases the diffuse reflection of light by leaves in the entire visible region., Three PL bands were observed in the photoluminescence spectra of untreated leaves: one of low intensity with a maximum at 535 nm, and two intense bands with maxima at 685 and 740 nm. The latter two bands of red luminescence correspond to the emission of the molecules of chlorophyll a, while the band at 535 nm may be ascribed to the emission of carotenoids in the leaves. The application of the SrAl2O4:Eu,Dy+H2O suspension practically does not lead to a change in the spectrum of intrinsic "red" PL of the leaves in the region of 625–825 nm. At the same time, for leaves coated with the SrAl2O4:Eu,Dy+H2O+PVA suspension, there is an increase in the luminescence intensity in the region of 450–650 nm, compared to the intensity of the band at 685 nm. The relative intensity of the PL band at 740 nm, however, decreases. It has been demonstrated that the PL spectra of the samples are sensitive to changes in the PL excitation wavelengths, ghat allows for selective excitation of the photoluminescence of the phosphor label and chlorophyll a contained in the leaf. The obtained results indicate the possibility of using the optical properties of leaves treated with suspensions to collect information about the condition of the plant, with the aim of applying the Internet of Things (IoT) concept in crop production. Key words: chlorophyll, light absorption, luminescent marker, photoluminescence
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Comprehensive approach to energy efficiency assessment of induction furnaces under unstable power supply
A comprehensive approach to evaluating the energy efficiency of induction furnaces under unstable power supply has been developed, integrating electromagnetic, thermodynamic, and stochastic models. The influence of power grid parameter fluctuations on electromagnetic field penetration depth, eddy current distribution, and temperature gradients in the melt has been investigated. The nonlinear nature of heating power dependence on voltage and frequency deviations has been established. A mathematical model for probabilistic assessment of energy losses under various types of power supply anomalies has been formulated. A methodology for calculating integral energy efficiency indicators has been developed, including the coefficient of variation of efficiency and the probability of ensuring a minimum acceptable efficiency level. A phenomenological analysis of the relationship between power quality indicators and thermodynamic characteristics of the melting process has been conducted. Theoretical principles for constructing adaptive control systems for induction furnaces based on predictive models of power grid fluctuations have been substantiated. The research results create a theoretical basis for developing intelligent control systems for induction melting units capable of ensuring an optimal balance between energy efficiency and product quality. Key words: induction furnace, energy efficiency, unstable power supply, electromagnetic field, stochastic modeling, adaptive control, metallurgical processes
Research on the influence of the specific density of the raw material fermented in a biogas reactor on heat distribution
Biogas technologies are becoming increasingly widespread in industrial and domestic facilities. However, the profitability of biogas production depends on the energy consumption to support the fermentation process, so it is necessary to conduct research aimed at reducing energy costs for heating and mixing the raw material being fermented. Raw materials with different physicochemical compositions are used for fermentation, which significantly affects energy costs. The aim of the work is to study the influence of the specific density of the raw material being fermented in a biogas reactor on the energy costs for mixing and changing the Reynolds criterion. The paper presents the constructed mathematical model and research results. The research considered a wide range of changes in the specific density of the substrate from 750 to 1500 kg/m3. According to the research results, graphical dependences of the change in the Reynolds criterion, heat transfer coefficient and heat transfer coefficient were obtained, depending on the change in the specific density of the raw material and the frequency of rotation of the working body of the mixing device. It has been established that the change in the criterion and coefficients depending on the change in the density of the raw material occurs according to a linear law. The results obtained will allow setting a rational rotation frequency of the mixing device in which the heating device is located from the point of view of energy consumption for the processes of mixing and electrical heating of the raw material. Key words: Reynolds criterion, heat transfer coefficient, heat transfer coefficient, specific density of raw materials, anaerobic digestion, mixing
Experimental study of heat and mass transfer in solid dispersed materials during vapor-depression drying
The intensity of technological processes involving dispersed materials is most often limited by the speed of internal mass transfer. The vapor-depression drying method, developed by scientists of the Institute of Thermal Physics of the National Academy of Sciences of Ukraine, allows for the intensification of internal moisture transfer and thus creates the prerequisites for accelerating the drying process. The vapor-depression drying process has been considered in detail in the literature for the case of drying a capillary-porous body - sheet plaster. The purpose of this study is to consider the effect of a vapor-permeable shell on the intensification of internal mass transfer during the drying of a capillary-porous colloidal body - viscose fiber. In experimental studies, ordinary knitted shells and shells with increased density, as well as cloth and paper shells were used. The absence of a clearly defined period of constant drying speed was recorded, which indicates a low intensity of moisture transfer in the material. The highest values of the drying speed are achieved when using a single knitted shell, the lowest - when dewatering the fiber in a cloth shell. The obtained experimental data can be used to develop effective methods for controlling the drying processes of solid dispersed bodies. Key words: vapor-depression drying, solid dispersed bodies, vapor-permeable shell, drying rate
Experimental study of the operation of a Stirling engine with a solar concentrator and an additional energy source
The efficiency of solar energy is limited by the natural variability of solar radiation levels. The Stirling engine is a promising solution for solar energy systems, especially when using concentrators, such as a Fresnel lens. The main obstacle to the widespread implementation of such systems is their dependence on the stability of solar radiation. The purpose of the research is to create an experimental stand and methodology to determine the feasibility of using an additional energy source (electric heater) to prevent the shutdown of the Stirling engine, which uses concentrated solar radiation using a Fresnel lens as the main source of heat. The paper presents an experimental study of the Stirling engine, which includes the study of the effect of variable insolation and the assessment of the efficiency of using an electric heater as an additional energy source (AES) to improve system stability. A series of experiments was conducted with different durations of insolation interruption (20, 40 and 60 s). The results confirmed the ability of the AES to prevent engine shutdown and increase the total energy produced by 47 %, 90 % and 130 % for the respective intervals. Key words: Stirling engine, Fresnel lens, additional energy source, power stabilization, solar energy, experimental stand
Research on the efficiency of using solar tracker in urbanized conditions
In the context of rising energy prices and the need for energy independence, the development of renewable energy sources, in particular solar, is becoming particularly relevant. Solar power plants (SPPs) on the roofs of multi-story buildings are a promising solution for urban environments, where the area for ground-based installations is limited. To maximize electricity production from a limited area, it is critical to use technologies that increase system efficiency. Solar trackers, which automatically orient photovoltaic modules perpendicular to the sun's rays, are one of the most effective tools for achieving this goal. The main objective of this study is to analyze the technical and economic feasibility of implementing different types of solar trackers for a solar power plant located on the roof of a typical nine-story building. The objectives are: • to conduct a comparative analysis of single-axis (HSAT, VSAT, tilted axis) and dual-axis trackers; performing technical generation calculations and assessing the impact of key factors such as spatial constraints, shading and temperature; • assessing economic feasibility, taking into account initial investments and payback; • providing sound recommendations for two specific locations in Ukraine: Zaporizhia (south) and Ivano-Frankivsk (west). Key words: photovoltaic module, solar tracker, single-axis trackers, temperature, insolation, multi-storey building
Modeling of an energy efficient fan installation based on an adjustable electric drive with a fuzzy logic regulator
Centrifugal fan installations are the most common in various spheres of production, both light and heavy industry. More often, centrifugal fans are installed as unregulated electric drive installations, especially low capacity. But there are a lot of technological equipment, especially in the production sphere, where it is necessary to regulate the productivity of fans. Moreover, regulation is carried out in a fairly wide range. Electrical drive of centrifugal fans is usually realize on the basis of an asynchronous short -circuited engine. To adjust the supply of such fan is carried out the adjusting of the speed rotation of the engine using the frequency converter Among the known ways of regulating the efficiency of fan installations, namely throttling, change of the angle of installation of blades, using of guiding machines, regulating of the number of rotations of the fan shaft is the most effective way. In modern conditions, the change of the fan shaft rotation is carried out by changing the drive shaft rotation of drive engine. In the article is considered the issue of increasing the energy efficiency of fan installations by using an adjustable electrical drive with using the regulator, built on the principles of fuzzy logic. The mathematical model of the system in the Matlab application package has been developed, computer modeling has been carried out and the benefits of the proposed approach are shown in comparing to the traditional methods of regulation. Key words: fan installation, energy efficiency, adjustable electrical drive, asynchronous engine, sub- regulator, fuzzy logic controller, Matlab
Study of the influence of changes in the motor speed on the technological characteristics of a feed pellet mill
The influence of changes in the motor speed on the pellet mill performance, as well as on the technological and energy parameters of feed pellet mills is investigated. The dependencies between the motor speed and such indicators as productivity and general characteristics of the equipment operation are revealed. Productivity increases with increasing speed up to a certain point, but for most feeds, there is a stabilisation or even a decrease in productivity after reaching the maximum level. Different feeds have their own optimal characteristics: soybeans and a mixture of cereals are better suited for pellet mills due to their higher productivity, while barley has a much lower productivity, so it is necessary to make adjustments to the technological process (change the structure, moisture content or other parameters). Feed moisture content in the range of 9-9.6% contributes to high productivity, while barley has the lowest productivity even at optimal moisture content, which may be due to its physical properties. The research allows us to determine the optimal operating modes of the pellet mill, which achieve the production of high-quality feed with minimal energy consumption. Further research can be aimed at studying the influence of other parameters, such as temperature and the addition of various components. Deviations in the change in the motor speed lead to a disruption in the stable flow of technological processes, a decrease in product quality, a reduction in the service life of electrical equipment, an increase in electricity losses in power consumption systems, and the creation of emergencies that can threaten human safety [1]. Key words: feed pellet mill, electric drive, performance, frequency converter, network analyser
Research and analysis of testing nonlinear overvoltage limiters for high-voltage electrical networks
Research and analysis of nonlinear surge arresters (NSAs) for high-voltage electrical networks is a key process for assessing their effectiveness, reliability, and compliance with standards, which includes: determining NSA characteristics, conducting laboratory and field tests, simulating their operation, analyzing the results, and comparing them with regulatory requirements to ensure the protection of networks from overvoltages. The paper provides a detailed analysis of the testing of AZBD series surge arresters, as well as a study of the surge arrester for a 220 kV high-voltage electrical network of the type OPN-P-220/158/10/2 surge arrester with residual voltage values of 510 kV and 574 kV at a lightning impulse current of 8/20 μs with amplitudes of 10 kA and 20 kA, respectively, and 402 kV and 419 kV at a switching current pulse of 30/60 μs with an amplitude of 500 A and 1000 A, respectively. This article analyzes the testing of surge arresters with short-circuit currents, describes the charge transfer characteristics and energy capacity of surge arresters, presents new tests in accordance with DCU EN 60099-4:2016, and verifies the characteristics of surge arresters after applying bending loads and testing for resistance to environmental influences. A brief description of the structural and basic electrical diagram of the test setup used in the laboratory of electrical installations and power supply systems for testing surge arresters, valve arresters, vitelline discs, and spark gaps of various voltage classes is provided. The volt-ampere characteristics of the surge arrester, the dependence of the residual voltage on the impulse current, and the dependence of the leakage current on the alternating voltage were constructed. Additional graphs were also constructed for the OPN-P-220/158/10/2 surge arrester, an approximation graph (U = a·Ib) with the obtained equation, a graph of dynamic resistance R = U/I as a function of current, and the dependence of residual voltage on the conditional pulse energy. These graphs together provide a complete picture. In particular, the approximation describes the general mathematical relationship; the dynamic resistance R(I) shows the effectiveness of the limiter; the relationship between the residual voltage and energy U(E) allows us to evaluate the behavior under pulses of different nature. Key words: electrical networks, nonlinear surge arresters, lightning discharge, impulse current, residual voltage, pulses
Development of software for controlling the movement of jib crane mechanisms
The article provides an overview of software products from leading developers of software for the operation of cranes. The statement and solution of the problems of optimal control of the movement of the mechanisms of load hoisting and slewing the jib crane in the acceleration and braking modes are presented. Calculations were carried out for three quadratic integral quality criteria, which reflected the driving factors and their higher derivatives in time up to the second inclusive. The laws of change of the driving elements (angular velocities of the drives of the mechanisms) were obtained, which ensure the implementation of optimal control. The software "Optimal control of the movement of jib crane mechanisms" was developed, which allows using frequency-controlled drives of both mechanisms to implement optimal control in practice. A description of the communication settings between frequency converters and a computer with the developed software via a serial communication port is presented. The sequence of actions of the user of the software product is shown in order to calculate the optimal laws of motion, their visualization and transmission of control commands to frequency converters to perform tasks of optimal control of the movement of mechanisms. Key words: hoisting crane, software, optimal control, development
Dynamics of a double-head streamer in air: numerical analysis for an inter-electrode gap of 0.3 cm
The work investigates the dynamics of a double-headed streamer discharge in air at 14 kV using hydrodynamic modeling. Numerical simulations in COMSOL Multiphysics (2D axisymmetric geometry, finite element method) revealed significant differences in the development of positive and negative streamers in a 0.3 cm gap: the negative streamer shows high initial velocity (0.4 cm/ns) that rapidly decreases, limiting its maximum propagation distance (0.15 cm), while the positive streamer accelerates over time (up to 0.0378 cm/ns), covering a greater distance (0.14 cm) due to higher electron density (up to 3.34×10²⁰ 1/m³) and more intense electric field (375×10⁵ V/m vs 119×10⁵ V/m for the negative one). The obtained results confirm the model's ability to accurately reproduce spatiotemporal evolution of streamers, which is crucial for high-voltage device development and breakdown analysis. The study was conducted at 760 Torr with a time step of 0.05 ns over 3.75 ns. Key words: double-headed streamer, streamer discharge, numerical simulation, air gap, interelectrode gap, COMSOL Multiphysics, hydrodynamic model, positive streamer, negative streamer, air breakdown, high-voltage discharge
Optimization of glass furnace heat recovery exchanger parameters
The research results on the efficiency and optimization of glass furnace heat recovery exchangers parameters using complex methods, including exergy analysis methods and optimization algorithms used in statistical experimental design theory are presented. Two types of heat recovery exchangers using the heat from exhaust gases of glass furnaces were investigated. This is an air-heating heat recovery exchanger (end recuperator) designed to preheat cold air before it enters the furnace regenerator, and a water-heating heat recovery exchanger with a staggered and corridor arrangement of pipes in a bundle, which is used in schemes for heating water in heating systems. To optimize the heat exchange surface parameters of heat recovery exchangers, a complex methodology has been developed based on an exergy approach and the canonical transformation method used in statistical experimental design theory. Within the framework of the exergy approach, exergy criteria are used that can serve to evaluate the exergy efficiency of heat recovery exchangers and as optimization objective functions (response functions) when solving optimization problems. The canonical transformation method is used as the optimization algorithm, which allows obtaining a graphical interpretation of the optimum region for the response function in the form of a series of contour curves on a plane. Functional dependencies of the efficiency evaluating criteria for air-heating and water-heating heat recovery exchangers on their main parameters in canonical form have been obtained. Graphs of specified dependencies and graphical interpretations of the optimum regions for response functions are presented in the form of a series of contour curves on a plane. A detailed study of response surfaces in the response function minimum region was conducted, and the optimal regions of geometric parameters for the heat exchange surface of air-heating and water-heating heat recovery exchanges were determined. When determining the intervals for changing parameters based on the optimal parameters exact values, the technological requirements for the heat exchange surface of heat recovery exchangers were also taken into account. The research conducted will serve to develop increased efficiency heat recovery systems.
Electroelastic bulk and normal shear waves in a layered-periodic medium of the type metal-piezoelectric-dielectric
A method for constructing dispersion relations for bulk and normal electroelastic shear waves propagating in layered-periodic media formed by repeating a "generating" metallized package consisting of a piezoelectric layer and a dielectric layer that has no electrical properties is proposed. As a result of the analytical calculations, dispersion relations for normal and bulk electroelastic shear waves were obtained. CdS or ZnO were considered as piezoelectric materials, and the dielectric layer was chosen with the parameters GaYIG. The obtained dispersion relations were numerically analyzed for different geometries and physical properties of the materials forming the "generating" package. . Numerical analysis showed that a feature of the obtained bulk wave spectrum is that in the range of changes in the wave number and circular frequency, the zone boundaries do not intersect. The spectrum of normal waves is localized in the transmission zones of bulk waves except for one dispersion curve. The influence of physical, mechanical and geometric parameters of the layers on the structure of the blocking and transmission zones has been studied, as well as the influence of the piezoelectric effect has been investigated. Based on the approach proposed in the works of M.O. Shulga, the problems of bulk and normal electroelastic waves are reduced to the study of the properties of the transmission matrices of the "generating" package of layers, through the elements of which the desired dispersion relations are expressed. In the work, it was possible, using the condition of metallization on the outer surfaces of the package, to write the dispersion relations through the elements of second-order matrices instead of the fourth, which allows simplifying the analysis of the dispersion equations. Key words: bulk and normal shear waves, periodic layered structure, piezoelectric, dielectric, transmission zones, bulk wave blocking zones
Theoretical study of the motion of material particles in centrifugal devices with curved blades and variable angle of their rise
In centrifugal scattering devices, the blades provide the necessary trajectory and speed of the particle in relative motion. The operation of scattering devices with straight blades has been sufficiently studied. From a theoretical point of view, it seems interesting to study the motion of a particle along a curved blade, when the angle of elevation of the particle increases from zero to a given value at the moment of its descent from the blade. The purpose of the study is to perform a comparative analysis of the motion of a particle along straight and curved blades, which provide a given angle of elevation of the particle at the moment of its descent from the blade. When a disk with a curved blade rotates, the particle performs a complex motion: translational due to the rotation of the disk and relative along the blade. To compile the differential equations of motion, it is necessary to find the absolute acceleration vector, which includes three components: acceleration in translational motion, acceleration in relative motion, and Coriolis acceleration. This vector is conveniently searched for in the projections onto the orthogonal surfaces of the accompanying trihedron of the translational motion curve, which for the rotational motion of the disk will be a circle. Generalized differential equations of particle motion in centrifugal devices along a curved blade with a variable lift angle have been derived. A comparative analysis of the kinematic parameters of motion for straight and curved blades has been performed. A comparative analysis of particle motion along straight and curved blades of a centrifugal scattering device has shown that a particle along a curved blade in the form of an arc of a circle of the specified length accelerates faster than along a straight one. Thus, replacing straight blades with curved ones allows achieving the same effect while reducing the angular velocity of disk rotation from 25 rad/s to 23 rad/s, i.e., the reduction is 8%. With an unlimited length of the blade in the form of an arc of a circle, the particle performs an oscillatory motion along it up and down with damping until it comes to a complete stop in the presence of friction. Key words: curved and rectilinear blades, differential equations, lift angle
Current state and prospects of energy-saving development of vegetable storage engineering systems in Ukraine and the world
Збереження свіжості та якості овочів є важливим завданням для аграріїв у всьому світі, включаючи Україну. На тлі зростання цін на енергоносії, енергоефективність систем зберігання овочів стає особливо актуальною. Тому сучасні технології зосереджуються на розробці енергоощадних інженерних рішень для овочесховищ, спрямованих на зменшення енерговитрат та екологічного впливу. Особливу увагу приділяють оптимізації умов зберігання, автоматизованим системам керування мікрокліматом та використанню відновлюваних джерел енергії. У статті розглянуто сучасні тенденції та перспективи розвитку енергоефективних інженерних систем для овочесховищ в Україні та світі. Наголошено на важливості оптимізації мікроклімату для збереження продукції та мінімізації енергетичних витрат. Дослідження базується на аналізі наукових публікацій, нормативних документів та аналітичних даних щодо вентиляційних, холодильних систем та автоматизації мікроклімату овочесховищ. Проведено порівняльний аналіз традиційних та сучасних технологій зберігання, включаючи застосування чисельного моделювання гідроаеродинамічних процесів (CFD) для оцінки ефективності систем підтримки мікроклімату. Визначено, що інтеграція відновлюваних джерел енергії (сонячних панелей, теплових насосів, систем акумуляції холоду) суттєво знижує енергоспоживання овочесховищ. Використання CFD-моделювання дозволяє оптимізувати параметри повітрообміну, температури та вологості, що сприяє зменшенню втрат продукції та оптимізації енергоспоживання. Аналіз сучасних технологій свідчить про зростаючу роль інтелектуальних систем керування мікрокліматом, що дозволяють автоматично регулювати параметри повітряного середовища та забезпечувати оптимальні умови для збереження овочів. Впровадження енергоефективних технологій зменшує операційні витрати та мінімізує екологічний вплив. Досліджено концептуальні підходи до підвищення ефективності зберігання овочів, що базуються на поєднанні CFD-моделювання, автоматизованих систем керування мікрокліматом та інтеграції відновлюваних джерел енергії. Впровадження цих підходів сприятиме покращенню якості зберігання продукції, зниженню енергоспоживання та збільшенню економічної ефективності овочесховищ. Подальші дослідження у сфері CFD-моделювання є важливими для вдосконалення технологій розподілу повітряних потоків, вологості та температури, що дозволить підвищити ефективність інженерних систем для зберігання овочів. Ключові слова: мікроклімат овочесховищ, інженерні системи овочесховищ, енергоефективність, CFD-моделювання, відновлювальні джерела енергії, вентиляція
Electrotechnological complex of plants energy-efficient irradiation in greenhouses
The electrotechnological complex of energy-efficient irradiation of plants in greenhouses is an important aspect in modern agro-industrial production, as it provides optimal conditions for plant growth and development, reducing energy consumption. This complex uses modern lighting technologies that allow for the effective use of natural and artificial lighting, optimizing its intensity and spectrum to ensure maximum photosynthetic effect. One of the main principles of energy-efficient irradiation is the use of light-emitting diode (LED) lamps, which makes it possible to regulate the light spectrum, adapting it to the specific needs of plants. These lamps have high energy efficiency and a long service life, which allows reducing electricity and maintenance costs. In addition, the use of automated control systems, such as light and temperature sensors, allows maintaining an optimal microclimate in greenhouses. Integration of such systems into agro-industrial complexes allows not only to increase yields, but also to reduce the impact on the environment due to the rational use of energy. The development and implementation of energy-efficient irradiation technologies in greenhouses is an important step towards the sustainable development of the agricultural sector, in particular in the context of climate change and increasing demand for environmentally friendly products. Key words: electro-technological complex, energy efficiency, plant irradiation, greenhouse, LED lighting, automation, agro-industrial production
Efficiency of carbon dioxide capture in a rotating packed bed with diifferent absorbents
One of the effective approaches to reducing CO₂ emissions is the use of liquid absorbents in various types of contact devices, particularly in centrifugal rotating packed bed (RPB) absorbers. This study presents a comparative analysis of chemical liquid absorbents (NaOH, MEA, piperazine) based on mass transfer efficiency, thermal and oxidative stability, regeneration energy demand, and economic feasibility. It was found that centrifugal contactors demonstrate a significantly higher volumetric mass transfer coefficient compared to conventional packed absorption columns, especially when using MEA. The influence of absorbent concentration and hydrodynamic parameters on mass transfer intensity was analyzed. The results show that piperazine, despite its higher cost, provides the best operational performance. The research offers a foundation for selecting absorbents considering both technical and economic parameters as well as mass transfer efficiency, aimed at compact and energy-efficient CO₂ capture systems. Key words: liquid absorbents, rotating packed bed, CO2 capture, mass transfer
Energy efficiency of heat pump continuous flow grain dryers
Grain drying is an energy-intensive stage of post-harvest processing, where the use of heat pumps is one of the methods to improve energy efficiency. The paper provides concise information on drying technology, types of dryers, and their features. Particular attention is paid to recirculation schemes of the drying agent, which reduce energy consumption by reusing the heat carrier. Modern approaches to integrating heat pumps into continuous flow grain dryers systems are discussed, enabling dual functionality: dehumidifying air in the evaporator and heating it in the condenser. The article proposes a methodology for assessing the energy efficiency of grain drying in heat pump continuous flow grain dryers. The study also analyzes the influence of the non-isenthalpic drying mode in continuous flow dryers, a key feature that differentiates them from chamber systems. Recommendations for optimizing drying parameters to reduce energy consumption and improve dryer efficiency are provided. The research findings may be useful for agricultural enterprises seeking to modernize post-harvest grain processing technologies. Key words: grain dryer, energy efficiency, recirculation, heat pump, flow-through dryers, chamber dryers, grain moisture
Analysis of direct mechanical into thermal energy conversion using eddy currents
The article presents the results of an experimental study on the operation of an induction heat energy generator, which implements the conversion of mechanical energy from the rotation of a magnetic disk into thermal energy through eddy currents induced in a conductive metal plate by an alternating magnetic field. The object of the research is the process of direct conversion of mechanical energy into heat. The experimental setup consists of a rotor with permanent magnets arranged in a circular pattern, rotating above a steel plate. As the magnetic field moves relative to the conductor, eddy currents are induced, resulting in heating due to Joule losses. The influence of the structural and magnetic parameters of the setup on the amount of thermal loss power is investigated, particularly the frequency of magnetic field variation, the magnetic flux density, and the distance to the plate. To verify the experimentally obtained values, a theoretical formula for calculating eddy current power loss was used, which accounts for the magnetic induction, frequency of field variation, and the electrical properties of the material. A comparison between theoretical and experimental results showed a discrepancy of less than 10%. The obtained results can be applied in the development of contactless heating systems, energy recovery systems, and power units with direct mechanical-to-thermal energy conversion, especially for wind and hydraulic turbines. Key words: renewable energy sources, wind energy, induction heating, eddy currents, permanent magnets, heat energy generator, contactless heating, direct energy conversion, rotational motion
UTILIZATION OF WASTE HEAT FROM TECHNOLOGICAL EQUIPMENT TO IMPROVE THE ENERGY EFFICIENCY OF VENTILATION SYSTEMS
The article analyzes various possibilities for utilizing waste heat removed from installed equipment at industrial enterprises. A comparison of different types of systems is presented, highlighting their advantages and disadvantages. Calculations using the h–d diagram were carried out for different outdoor air temperatures for three system configurations: a straight-through system (without heat recovery), a system with air recirculation, and a system with a two-level mixing chamber. The advantages of using an adaptive system with a two-level mixing chamber compared to the traditional air recirculation scheme are demonstrated. It is shown that, under certain operating modes, the adaptive system can reduce operational costs by more than 10 times. Technical barriers to the implementation of an adaptive system with a two-level mixing chamber are also discussed. Key words: energy efficiency; adaptive system; air recirculation; heat recovery
Increasing the efficiency of electricity use by residential and public buildings in the presence of hybrid solar power plants in the electricity market
The article is devoted to the analysis of electricity consumption schedules of public and residential buildings and the operation and optimization of the operation of rooftop hybrid solar power plants. The wide distribution of hybrid solar inverters, due to both the desire to reduce energy consumption costs and the need to provide backup power to critical consumers, created prerequisites for using the advantages of the electricity market. Storage and the possibility of interchangeability of energy sources (for example, district heating and electricity supply for heating and hot water supply) allows us to talk about buildings in the context of "active consumers". The developed standard schedules of electricity consumption by buildings allow optimizing the use of their own solar power plant to minimize the cost of electricity supply, taking into account the possibility of storage systems and the possibility of using surplus solar generation for heating, air conditioning and hot water supply. The simulation of the solar power plant operating modes in the following options: "consumption for own needs without optimizing the use of storage systems", "sale of surplus electricity on the market", "consumption for own needs with optimization of storage systems" indicates the possibility of reducing the cost of energy consumption of the facility by 30-40% depending on the daily solar insolation. The use of the model allows you to configure the operating modes of hybrid inverters to optimize energy consumption. It is advisable to focus further research on the creation of an alternative control system for inverters with optimization depending on the load profile of the building. Key words: hybrid power supply, energy consumption modeling, cost optimization, demand side
Scientific foundations of designing specialized agricultural bioengineering complexes
The article considers the design of specialized agricultural bioengineering complexes for biological plant protection based on the use of ontologies. The aim of the study is to develop scientific foundations for the design of specialized agricultural bioengineering complexes. The object of research is specialized agricultural bioengineering complexes. The subject of the research is the use of an ontological approach to the design of intelligent information systems for biological plant protection. Research methods – systemic approach, ontological engineering, free software environment Visual Understanding Environment. An analysis of research by domestic and foreign scientists on the design of specialized agricultural bioengineering complexes was conducted. The processes of designing an intelligent information system for biological plant protection are formalized in the form of ontologies, in particular, structuring actions to manage the production of biological plant protection products (at the technocenosis level), structuring actions to manage the use of biological plant protection products (at the agrotechnocenosis level), and developing a knowledge base of an intelligent information system for biological plant protection. The advantages of using ontologies in designing an intelligent information system for biological plant protection are automation of knowledge analysis, aggregation of knowledge, and increasing the level of competence of a human technologist in the processes of production management and the use of biological plant protection products. Key words: agrotechnocenosis, knowledge base, biological plant protection, intellectual information system, ontologies, technocenosis
Influence of voltage deviation on the angular speed of series-excitated DC motors
Series-excited DC motors are the most common DC motors used in mobile machines. In these motors, the magnetic flux depends on the motor load. Since the magnetization curve of the electric motor is nonlinear, it is not possible to obtain an analytical expression for the mechanical characteristics of the motor. Therefore, the operation of the motor is considered in an unsaturated magnetic system and a saturated one. The purpose of the study is to analyze the influence of voltage deviation on the angular speed of working machines with a series-excited DC motor. As a result of the conducted research, the dependences of the angular speed of a series-excited DC motor on voltage for working machines with different types of mechanical characteristics in an unsaturated and saturated magnetic system were established. It was established that the law of change of the angular speed of the electric drive when the supply voltage deviates is determined by the mechanical characteristic of the working machine. For working machines in which the moment of static resistance does not depend or linearly depends on the angular speed, the angular speed changes linearly with the change in voltage. For working machines with nonlinear mechanical characteristics, the change in the angular speed of the electric drive when the voltage deviates occurs according to a complex algorithm. The influence of the thyristor voltage converter on the power supply network was also studied. The third, fifth and seventh harmonics were found in the harmonic spectrum. Key words: electric drive, series-excited DC motor, angular speed, voltage deviation, mechanical characteristic of the working machine, thyristor voltage converter, higher harmonics
Increasing the efficiency of heat utilization of exhaust air from combustion chambers by conversion into electrical energy
The article is devoted to solving the urgent problem of increasing the energy efficiency of thermal processes by implementing the latest technology using thermoelectric modules as an alternative source of electricity that uses waste heat. The purpose of the study is to develop and experimentally verify the operability of an autonomous system for recovering heat losses from the combustion chamber of hydrocarbon-water mixtures based on thermoelectric generators. The experimental setup included a commercial module TEC1-12715, which at a temperature gradient of ≈40°C (141°C / 101°C) generated a voltage of 1.56V and a current of ≈0.32A, which corresponds to a power of ≈0.49W. A DC-DC converter (2V → 24V) was used to increase the voltage. The practical suitability of the system was tested on the example of powering a low-power electrical load. The temperature field was assessed during the experimental study using thermal imaging measurements and a non-contact thermometer. A three-dimensional model of ten pairs of P/N-Type elements was developed, which takes into account thermal conductivity and thermoelectric effects. To assess the efficiency of the module, numerical simulation was performed in COMSOL Multiphysics, where a three-dimensional model of an element with 10 thermocouples was created. Under similar temperature conditions, it provided an output voltage of 0.144V. Extrapolation to a full module with 127 pairs gave a theoretical value of ≈1.83V, which is ≈14.7% higher than the experimental results. The discrepancy is explained by thermal losses and idealized modeling conditions. The results obtained confirm the potential of TEG for utilizing low-potential heat and powering auxiliary devices in autonomous power systems. Prospects for further development of the system include the use of materials with a higher Seebeck coefficient; improvement of the cooling system, in particular with the use of CFD analysis; implementation of buffer energy storage for pulsed power supply of loads. Key words: thermoelectric generators, heat recovery, heat loss utilization, water-hydrocarbon mixtures, boost converter, combustion chamber, COMSOL Multiphysics software environment, temperature gradient
Optimization of heat recovery system parameters with a glass furnace recuperator
The modern development of the energy sector is characterized by a significant increase in the cost of energy and natural resources, as well as growing requirements for environmental protection from the impact of waste produced by municipal and industrial enterprises. Currently, the problem of energy saving in the municipal heat-power engineering is to some extent solved by recovering the heat of fuel combustion materials. Increasing the efficiency of the relevant heat recovery equipment is important and urgent. The purpose of the study is to optimize the parameters of a heat recovery system with a regenerative-type industrial furnace recuperator based on a complex multi-level optimization, statistical theory of experiment planning, and functional analysis. To achieve this purpose, the following tasks were set: to develop a multi-level optimization scheme and a recursive bypass scheme of optimization levels for a heat recovery system with a glass melting furnace recuperator; to develop mathematical models for each optimization level and obtain functional dependencies of the system efficiency assessment criteria on the main parameters based on statistical methods of experiment planning and functional analysis methods; to determine the optimal values of the operating and constructive parameters of the heat recovery system. The basic principle of the multi-level optimization method is as follows. When constructing a mathematical model of each optimization level, the variable parameters are the parameters that vary for the objects of this level, and the constant parameters are the optimal parameters that are the results of solving local optimization problems of other levels. The main task when using the statistical methods of the experiment planning theory and functional analysis methods is to determine the functional dependencies of the criteria for assessing of the studied heat recovery system efficiency on its main parameters. The research results of the operating and constructive parameters of a heat recovery system that includes a waste heat recuperator of a regenerative type gas-consuming industrial furnace are presented. The recuperator is designed to heat the combustion air by heat recovering of the exhaust gases after the furnace regenerators. The recuperators are assembled of the required number of modules depending on the exhaust gas consumption. The heat exchange surface of the module is made up of steel panels formed by pipes with membranes. Exhaust gases move in the inter-panel space, and air moves in the pipe space. To intensify heat transfer from the air side, the pipes have with flow turbulators. A multi-level optimization scheme and a recursive bypass scheme of optimization levels for the studied heat recovery system were developed. The optimal values of the operating and constructive parameters of the heat recovery system using the specified complex methodology were calculated. The methodology allows you to determine the parameters that are as close to optimal as possible. This increases the heat recovery efficiency of exhaust gases by an average of 2.5% to 3% compared to the efficiency of systems optimized using other optimization methods. Key words: heat recovery; heat recovery of exhaust gases; complex research methods
Analysis of relay protection systems of regional distribution networks with distributed generation sources
The article presents a comparative review and analysis of modern methods of functioning of relay protection systems of medium-voltage distribution networks with distributed generation sources (DGR). The analysis touched upon the main technical challenges associated with the active introduction of DGR, primarily renewable sources, into regional networks, which leads to a change in the directions of flows and currents in the network, violation of the conditions for ensuring selectivity, sensitivity and technically perfect coordination between protective devices. Special attention is paid to the features of relay protection of micro-power systems during the transition from network to island mode. The purpose of the study is to review and analyze modern methods and systems of relay protection of distribution regional networks with DRG, taking into account the features of their operation. The article studies traditional and innovative (adaptive, combined, based on sequential components, using phasor measuring devices and artificial intelligence) protection methods, their efficiency and ability to operate in characteristic modes. The comparative analysis was carried out taking into account known modern platforms, their advantages, complexity of implementation, requirements for communication channels, settings and tests, possible risks due to the complexity of relay protection systems. The key advantages and limitations of modern approaches to implementing relay protection, as well as current trends in the development of protection systems for active networks with a high share of DRG, are identified. It is shown that to ensure the reliability and safety of power supply in modern conditions, it is necessary to implement adaptive, intelligent and hybrid protection systems with the possibility of operating regional microgrids in island mode. As a rule, in distribution regional networks, protection systems based on current measurement are used, less often - based on voltage measurement or combined protection systems (based on current and voltage measurement). However, the change in the structure of power supply from centralized (with one-way current flow) to decentralized (with different DRGs) creates a serious threat to network protection systems in terms of reliability of operation, sensitivity and coordination of various protection elements. It is established that innovative methods demonstrate higher flexibility, accuracy and ability to self-organize. At the same time, they require more complex technical and software implementation, communication setup and relevant implementation experience. The reliability of protection in the future will be determined by the system's ability to adapt to rapid changes in operating mode, dynamic connection and change of DRG parameters, requirements for power supply of critical consumers even in the event of a transition to islanding modes when disconnected from the main grid. Key words: distributed generation, transient stability, protection coordination, islanding, distribution networ.
To the 60-year anniversary of Viktor Volodymyrovych KAPLUNA
Kaplun Viktor Volodymyrovych is a well-known specialist and scientist in the field of energy, has scientific achievements recognized by the domestic and scientific community. He has solved a number of scientific problems that have significant theoretical and practical significance for managing the reliability of electrical complexes based on devices with the shape memory effect, power supply systems with polygeneration, their technological structuring and increasing efficiency through dynamic energy management. During 2010-2011 - Director of the Research Institute of Electric Power Systems of NUBiP of Ukraine, 2011-2019 - Vice-Rector for Scientific and Innovative Activities of KNUTD. Since 2020 - Director of the Educational and Scientific Institute of Power Engineering, Automation and Energy Saving of NUBiP of Ukraine. V. V. Kaplun is one of the founders of the scientific direction and developer of unique technologies for controlling temperature regimes in electrical installations based on shape memory alloys. For the first time, the technologies for producing smart alloys were theoretically substantiated and developed, the characteristics of which exceed world analogues. The products have been implemented in more than 300 enterprises of the energy complex of Ukraine (Kyiv Cable Networks, Zaporizhzhia NPP, Kyivoblenergo, Kharkiv City Electric Networks, Ukrhydronergo, Vinnytsiaoblenergo, Cherkasioblenergo, etc.), Canada (energy company Ontario Hydro). He proposed new theoretical approaches to creating autonomous electromechanical complexes (generator-motor) with compensated asynchronous machines, which provided a significant increase in the energy efficiency of electrical engineering complexes of this class and made it possible to create technological platforms for autonomous power supply systems, which have been implemented in over 140 projects, including 22 facilities of NPP Ukrenergo, Darnytsia, Mostobud PJSC, Eastern Coal Company LLC, the National Space Agency of Ukraine, Roshen PJSC, the State Emergency and Technical Center of the Ministry of Energy of Ukraine, Kyivvodokanal PJSC, etc. A significant contribution of V. V. Kaplun is the development of the theory of optimization of local micro-energy systems based on reliability and cost criteria, which created conditions for the development of principles for the formation of technological structures with polygeneration, balancing models, theoretical and methodological tools for the formation of dynamic energy management systems. Significant results of V.V. Kaplun as an organizer of science is the launch and conduct of the professional accelerator "Energy Security in Wartime" (from 2022), which has become a platform for exchanging experience of business mentors for discussing and solving applied tasks of improving the quality of electricity, reducing losses, managing the reliability of distribution networks, etc., cooperation with stakeholders in the energy sector, promising programs have been formed to increase operational efficiency, an adaptive customer-oriented energy consumption management system ("DTEK Kyiv Regional Networks", "VAP-BUD", Derzhenergonadzor, "Sejm-93", "DTEK Kyiv Electric Networks", "Svitlotek", "Biotestlab", "DTEK Odessa Electric Networks"), the creation of an educational and scientific Digital Energy Cluster with the participation of the National University of Bioresources and Environmental Management of Ukraine, LLC "DTEK Networks", PJSC "Cherkasioblenergo", the Institute of General Energy of the NAS of Ukraine, LLC "482 solutions", the Law Firm Association "Consilium", LLC "Kampov Technology", LLC "Atmosfera", LLC "e-NEXT-Ukraine", which allowed to combine the production and research potential of its participants. Scientific and organizational activities have a wide range of projects: national consultant in the field of energy of the United Nations Development Program in Ukraine in the project "Integration of the provisions of the RIO Conventions into the national policy of Ukraine" (2014-2016), member of the Scientific and Technical Council of the Ministry of Energy of Ukraine (since 2021), member of the working group on the implementation of the Concept of the introduction of "smart grids" in Ukraine by 2035 under the Ministry of Energy of Ukraine (since 2023), member of the Scientific and Methodological Council of the Ministry of Education and Science of Ukraine of the G3 Electrical Engineering subcommittee (since 2024), participant in the working group of the Secretariat of the Cabinet of Ministers on the preparation of Ukraine's negotiating positions on the conclusion of the Agreement on Ukraine's Accession to the EU on energy issues (since 2024), vice-president of the Ukrainian Union of Industrialists and Entrepreneurs (since 2020) on issues energy saving and energy efficiency management. He is the head of the international grant projects LIFE22-CET-NS4nZEBs (New Skills for Nearly Zero Energy Buildings), LIFE23-CET-BUSHROSs (Building Up Skills for Home Renovation One-Stop-Shops), ERASMUS-EDU-2022-CB-VET (Vocational Education and Training For Green and Smart Energy in Buildings). Kaplun V.V. is the author of 216 scientific works, including 12 monographs, 3 textbooks and teaching aids, 33 patents and copyright certificates. For his significant contribution to the development of science and education in Ukraine, V.V. Kaplun was awarded the title of "Honored Worker of Science and Technology of Ukraine" (2016), he is a laureate of the State Prize of Ukraine in the field of science and technology (2017), awards Awarded with the Certificate of Honor of the Verkhovna Rada of Ukraine (2020). The editorial board of the journal "Energy and Automation" sincerely congratulates Viktor Volodymyrovych on his anniversary, wishes him good health, and further creative success in his activities.
Identification of rodents locations in fields for organization of protective measures in agronomy
One of the main problems of the agricultural sector of Ukraine is the reduction of yields due to the impact of pests, in particular mouse-like rodents. According to experts, in Ukraine, annual crop losses from rodents can be up to 20% depending on the level of the pest population. Accordingly, damage to grain crops due to rodent activity in 2020 was estimated at over 1.2 million tons, which in financial terms is more than 400 million hryvnias (according to the Ministry of Agrarian Policy and Food of Ukraine). The results of the article are the preparation and analysis of data from monitoring the terrain relief to identify mounds created by rodents. Microrelief analysis and construction of its DBSCAN model using synthetic LiDAR data, clustering of anomalous elevations by the method and saving the results for further analysis using the R programming language. Key words: fields, rodents, burrow identification, terrain, UAV, LiDAR, data analysis, machine learning, R language
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Influence of the amount of loaded substrate on the energy efficiency of biogas production
Today, humanity's need for energy resources increases annually. The high cost of raw materials (oil, gas, fuel) leads to the need to search for alternative energy sources. Today, the fermentation of organic agricultural waste in biogas plants is one of the most environmentally friendly and economically advantageous solutions for obtaining energy from waste in the form of biogas. Along with this, a side effect of fermentation of organic waste is the production of valuable environmentally friendly fertilizers. However, the formation of biogas is a complex technological process, since in the process of methanogenesis it is necessary to maintain artificially created microclimate parameters. The influence of external factors such as temperature, acidity level pH, humidity, the presence of chemicals in the substrate can create negative consequences for the methane formation process, up to a possible complete loss of the loaded substrate in the biogas reactor. In order to avoid such negative situations, very strict requirements are established for the technological processes of biogas formation. Domestic and foreign scientists theoretically and experimentally establish optimal conditions for the methane formation process. Among them, the greatest attention is paid to maintaining the acidity level and maintaining the temperature according to the conditions of the technological process of biogas formation. According to the conditions of the technological process, biogas formation occurs in three temperature modes: psychrophilic, mesophilic and thermophilic, for which certain limits of temperature fluctuations are established. The greatest temperature differences occur during the loading of a new substrate. In order to avoid the occurrence of a critical temperature difference during loading and unloading processes, the condition of thermal equilibrium in the methane tank was considered. Based on theoretical calculations, the ratio between the mass of the substrate present in the reactor and the loaded fresh substrate was determined. Key words: methane tank, substrate temperature, biogas, thermal equilibrium, ratio, substrate heat capacity
Role of sustainable aviation biofuels in the decarbonisation of aviation sector
Renewable energy, in particular bioenergy, makes a significant contribution to replacing fossil fuels and reducing greenhouse gas emissions. This is in line with the current challenge at the global level – the decarbonization of all sectors of the economy, including energy and transport. Due to the widespread use of renewable energy sources, significant progress has already been made in the decarbonization of the heat and electricity production sectors. At the same time, transport lags significantly behind these two sectors in introducing renewable energy carriers. Among other things, this is on account of the objective difficulty of electrifying the transport sector, and this especially applies to aviation and water transport. This determines an increased role of biofuels in the decarbonization of transport. Today, the contribution of aviation to the global greenhouse gas emissions does not exceed 3%. However, given the rapid development of this sector and the growth in fuel consumption in it, this contribution can increase significantly. In view of this, the International Air Transport Association and the International Civil Aviation Organization have set a goal of achieving carbon neutrality in aviation by 2050. It is important that in the implementation of this ambitious goal, 65% is allocated to the consumption of sustainable aviation fuels. In a general sense, sustainable aviation fuels are biofuels and synthetic fuels that can provide a high level of reduction in carbon dioxide emissions compared to the use of fossil fuels. The European Union also pays considerable attention to the issue of decarbonization of aviation, as evidenced by the adoption of a special ReFuelEU Aviation Regulation in 2023. This Regulation sets mandatory targets for the share of sustainable aviation fuels at all the EU airports and provides a more detailed definition of sustainable aviation fuels. The aim of the work is to identify the most promising types of sustainable aviation biofuels and kinds of feedstock for their production for the conditions of Ukraine. To achieve the goal of the work, an analysis of several fundamental aspects related to the production of sustainable aviation biofuels was performed, followed by a synthesis of the results for Ukraine’s conditions. These aspects include the current level of development and commercialization of technologies for obtaining sustainable aviation biofuels; relevant types of feedstock (biomass) and the possibilities of increasing their use; the requirements of Directive (EU) 2018/2001 (RED III) regarding the sustainability of liquid biofuels. Key words: renewable energy sources, decarbonization, sustainable aviation fuels, aviation biofuels, biomass