POWER ENGINEERING: economics, technique, ecology http://energy.kpi.ua/ <p>The journal "POWER ENGINEERING: economics, technique, ecology" (Short title: Power Eng.: Econ., Tech., Ecol) is the scientific professional publication of Ukraine in the field of technical sciences. Scientific direction - energy and energy efficiency.</p> <p>Registration number of the certificate on the state registration of the printed mass media of КВ №22857-12775ПР dated 14.06.2017.</p> <p>Category of readers: scientists, specialists on the subject of the journal, postgraduate students, students.</p> <p>Frequency of release: 4 times a year.</p> <p>Year of foundation: 2000.</p> <p>ISSN: 1813-5420 (Print), 2308-7382 (Online).</p> <p>Founder National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute". It is published according to the decision of the Scientific Council of NTUU "KPI".</p> <p>Publisher National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute".</p> <p>Publication language: Ukrainian and English.</p> <p>Editor in chief Yu.I. Yakimenko</p> <p>The journal is included in the list of professional editions of Ukraine in which the results of dissertation papers for obtaining the scientific degrees of a doctor and a candidate of sciences may be published in accordance with the Resolution of the Presidium of the Higher Attestation Commission of Ukraine dated 24.09.2020. No. 1188.</p> <p>The journal is included in:</p> <p>- Databases "Scientific Periodicals of Ukraine" NBUV;</p> <p>- the Ukrainian abstract journal "Dzherelo" (IPRI NAS of Ukraine);</p> <p>- electronic archive of scientific and educational materials of NTUU "KPI" ELAKPI;</p> <p>- Scientific periodicals of Ukraine URAN (OJS);</p> <p>- Google Scholar Scientific Search Engine;</p> <p>- WorldCat, BASE, Polska Bibliografia Naukowa, Academic Keys.</p> en-US <p><span style="text-decoration: underline;">Автори, які публікуються у цьому журналі, погоджуються з наступними умовами:</span></p><ol type="a"><li>Автори залишають за собою право на авторство своєї роботи та передають журналу право першої публікації цієї роботи на умовах ліцензії <a href="http://creativecommons.org/licenses/by/3.0/" target="_new">Creative Commons Attribution License</a>, котра дозволяє іншим особам вільно розповсюджувати опубліковану роботу з обов'язковим посиланням на авторів оригінальної роботи та першу публікацію роботи у цьому журналі.</li></ol><ol type="a"><li>Автори мають право укладати самостійні додаткові угоди щодо неексклюзивного розповсюдження роботи у тому вигляді, в якому вона була опублікована цим журналом (наприклад, розміщувати роботу в електронному сховищі установи або публікувати у складі монографії), за умови збереження посилання на першу публікацію роботи у цьому журналі.</li></ol><ol type="a"><li>Політика журналу дозволяє і заохочує розміщення авторами в мережі Інтернет (наприклад, у сховищах установ або на особистих веб-сайтах) рукопису роботи, як до подання цього рукопису до редакції, так і під час його редакційного опрацювання, оскільки це сприяє виникненню продуктивної наукової дискусії та позитивно позначається на оперативності та динаміці цитування опублікованої роботи (див. <a href="http://opcit.eprints.org/oacitation-biblio.html" target="_new">The Effect of Open Access</a>).</li></ol> kravkpi@ukr.net (N.O. Kravchuk) zakladniy@gmail.com (Oleg Zakladnyi) Mon, 23 May 2022 11:53:10 +0300 OJS http://blogs.law.harvard.edu/tech/rss 60 ESTIMATED PARAMETERS IN THE SYSTEMS OF A SINGLE-AXIS ORIENTACIS OF A PHOTOELECTRIC MODULE http://energy.kpi.ua/article/view/257249 <p><em>The development of "green" energy in Ukraine involves an increasingof the amount of electricity generated by photovoltaic modules (PMs). However, PMs have disadvantages associated with the inconsistency of electric generation in time due to the diurnal and annual motion of the Sun and to the shading of the modules. In order to maintain steady generation during the day and the year, there are two ways to minimize the impact of these factors.First one is to install an excess capacity which means higher cost of the solar plant and using an additional area.Second one isto apply a system of orientation PMs perpendicular to the sun's rays. </em></p> <p><em>In the article three cases of solar panels installation are considered: usinga two-axistracking system, using aheight tracking system and anazimuth tracking system. There wasgiven the method and algorithms of calculation and analysis the parameters of theuniaxialand biaxial tracking system when installed in Kyiv.The algorithm involves calculation the coordinates of Sun in any moment of time for the considered location, pass-through and absorptive capacityof the protective glass, estimation the amount of the direct and diffuse solar radiation and their impact on the total radiation on the surface of the photoconverter. There was made an estimation of energy usage efficiency levels for the considered systemsusing the proposed algorithm.</em></p> V. Korovushkin, V. Dubovyk, А. Bosak Copyright (c) 2022 http://energy.kpi.ua/article/view/257249 Mon, 23 May 2022 00:00:00 +0300 DYNAMIC CHARACTERISTICS INVESTIGATION OF THE SYSTEM "SOFTSTARTER - INDUCTION MOTOR" IN THE MODE OF OPERATION WITH REDUSED SPEED http://energy.kpi.ua/article/view/257265 <p><em>In the article operation of the system "softstarter - induction motor" with reduced speed is carried out. The relative cheapness of thyristor starting devices for induction motors in comparison with frequency inverters leads to their increasing of industry installation. However, the implementation of some modes of operation, such as rotation at a reduced test speed, may not always be possible for particular processes. This is especially true of increasing the amplitude of speed fluctuations with increasing motor torque. The paper presents the settings of the serial starter SSW900 from WEG, which affect the operation of the induction motor at low speed. To study the impact in the work, a model was compiled in the MATLAB software environment using the Simulink application. The correspondence of the parameters of the functional models to the settings of the existing soft-start device is determined. The reduction of the motor speed is provided by reducing the frequency and, accordingly, the amplitude of the voltage applied to the motor windings. To reduce the carrier frequency relative to the supply frequency, the mode of passing certain voltage half-waves is used. In MATLAB, this is achieved through the use of Pulse_generator blocks, which pass control pulses only at permitted intervals. By changing the opening angle of the thyristors, graphs of transients in velocity were obtained and the amplitudes of oscillations at the fan nature of the load were determined. In addition, the results of the study of the system on a physical model were obtained and a comparative analysis of the results was performed. Thus, the formation of reduced frequency, proposed in the development of a mathematical model in MATLAB provides a reduction in engine speed to 1/7 of the nominal. The amplitude of speed fluctuations when setting the maximum torque reaches values ​​that significantly limit the possibility of using this mode for long-term operation of the equipment, which is also confirmed by experimental studies.</em></p> A. Toropov, L. Toropova Copyright (c) 2022 http://energy.kpi.ua/article/view/257265 Mon, 23 May 2022 00:00:00 +0300 RESEARCH OF PHYSICAL PROCESSES IN LAMINATED MAGNETIC CORES OF ELECTRIC MACHINES http://energy.kpi.ua/article/view/257267 <p><em>The aim of this work is to use fast-moving processes to detect defects in the inter-sheet insulation of </em><em>laminated </em><em>magnetic c</em><em>ore</em><em> of electric machines. Violation of the sheet insulation causes increased eddy currents as a result of increased losses and integrated local overheating in the body of the magnetic c</em><em>ore</em><em>. The article develops a mathematical field model of induction distribution in a toroidal toothed magnetic c</em><em>ore</em><em> of an asynchronous motor series 4AA63V4U3 0.37 kW when superimposed on the back of the core of the power winding powered by a high frequency voltage source in the range. An experimental study of losses in the magnetic </em><em>core</em><em>t and the distribution of losses on eddy currents and remagnetization (hysteresis).</em></p> <p><em>When designing an electric machine, its operating characteristics, optimal operating modes, thermal condition and many other factors are calculated using the nominal values ​​of steel parameters, windings and all materials used in the machine. However, these materials do not always have the stated characteristics and quality. For example, during the manufacture and stamping of electrical steel sheets, it is exposed to a significant level of influence, which in some way affects its characteristics. In addition, even if we assume that during the production of all stages of manufacturing the material came flawlessly, the condition and as a result the parameters of materials and EM in general change during operation as a result of accidents or even simple aging and wear.</em></p> <p><em>Therefore, given these facts, it becomes clear that during planned or unplanned repairs it makes sense to check the condition of materials, insulation, as their condition depends on the allowable loads, temperature, etc. In particular, the state of the magnetic circuit largely determines the temperature around the conductors in the grooves and as a result determines how long the winding will actually last in contrast to the specified service life and rated power at which to use this EM.</em></p> <p><em>The concept of the state of the magnetic circuit can be divided into the state of electrical steel and the state of its insulation. The first component changes quite poorly during operation and is generally caused by the "aging" of steel if you do not take into account any serious damage as a result of accidents, but it can be damaged during manufacture. But the second component is significantly affected during operation and significantly determines the quality of the magnetic circuit as a whole.</em></p> V.V Chumak, М.А Kovalenko, Y.O. Trotsenko, Y.S. Ihnatiuk, A.S. Stulishenko Copyright (c) 2022 http://energy.kpi.ua/article/view/257267 Mon, 23 May 2022 00:00:00 +0300 APPLICATION OF CONDENSATION ECONOMIZERS ON GAS ENERGY AND WATER HEATING BOILERS http://energy.kpi.ua/article/view/257271 <p><em>The provision of increasing the level of safety of the power plant in case of emergency shutdown, as well as increasing the efficiency of the boiler is considered. Disconnection of CHP from the grid entails, first of all, the threat of cessation of heat water supply to the city and, as a consequence, human and material losses. One of the options to prevent or minimize the consequences of such an accident at municipal CHPs, which is a system of rapid power recovery of the power plant regardless of external circumstances by installing a condensing heat exchanger and turbine on the organic cycle Rankin. Such a turbine can serve as a start-up power source for the station, and work together with a steam turbine, increasing the efficiency of the unit as a whole. This system is universal for units running on natural gas.</em></p> Evgeniy Novakivskiy, Andrii Nedilko Copyright (c) 2022 http://energy.kpi.ua/article/view/257271 Mon, 23 May 2022 00:00:00 +0300 HEAT TRANSFER IN COIL HEAT EXCHANGERS WITH VARYING GEOMETRIC CHARACTERISTICS http://energy.kpi.ua/article/view/257272 <p><em>Coil-type heat exchangers are widely used in power industry and medical and electronic technology due to the relatively simple design of their basic elements, low operating costs, reliability and long service life. The process of designing the devices with coil heat exchangers requires choosing the tube surface configuration and taking into consideration the specific operating conditions, as well as thermophysical properties and parameters of the working fluid. One of the important factors that hinder the wider use of coil heat exchangers is the lack of reliable engineering techniques for calculating the heat transfer and aerodynamic drag. </em></p> <p><em>This study aimed to improve the technique of calculating the heat transfer and aerodynamics of coil heat exchangers by modifying the dependences that take into consideration the specific operating conditions and allow determining the design characteristics of one-layer recuperative coil heat exchangers mounted in annular channels under the conditions of partially twisted working fluid flow. In order to do that, the authors conducted a physical experiment using a test setup, both of which are described in the article in detail.</em></p> <p><em>The analysis of the experimental results on heat transfer in a coil heat exchanger under forced gas convection and laminar flow of the working fluid helped to establish the dependence of the heat transfer coefficient on the main geometric parameters of the heat exchanger and to determine the allowances taking into consideration the extent to which the heat transfer intensity is impacted by the step characteristics of the tube bundle and the gap between the tube bundle and the heat exchanger housing, thus making it possible to optimize the geometric characteristics of the coil heat exchangers mounted in annular channels for specific operating conditions.</em></p> V. Tuz, N. Lebed, M. Lytvynenko Copyright (c) 2022 http://energy.kpi.ua/article/view/257272 Mon, 23 May 2022 00:00:00 +0300 WATER DESALINATION USING ICE FREEZING IN ICICLES http://energy.kpi.ua/article/view/257273 <p><em>The aim of the study is to investigate the effect of initial salinity and water flow rate on desalination processes in icicles formed on horizontal nozzles.</em></p> <p><em>Experimental installation, is a frame on which are </em><em>fixed</em><em>: a container with initial salt water, impact surface, horizontal nozzles. Initial saline water of 10-30 g/l flowed out through the hole, fell and crushed against the impact surface, and then froze on the nozzles in the form of icicles. To investigate the degree of salinity, the icicles were divided into equal parts and melted.</em></p> <p><em>The results of the investigation show that the obtained water contains the most salts in those parts that are closer to the bases of the borules. At a flow rate of 2 ml/sec, the borules grew to their full length. The level of the option was defined as the ratio of initial water solubility to the received solubility and was 1.5 to 4, higher values were obtained at the flow rate of 1 ml/sec, and at the first intervals.</em></p> <p><em>Conclusions: The results of experiments showed that it is impossible to refine brackish water in 1 cycle. To obtain drinking water with salt concentration less than 0.5 g/l it is necessary to use several cycles of freezing-melting or to combine with other methods of desalination. It is necessary to control the optimum water consumption to ensure a higher degree of (solidification)desalination.</em></p> І. Puhoviy, A. Petrechuk Copyright (c) 2022 http://energy.kpi.ua/article/view/257273 Mon, 23 May 2022 00:00:00 +0300 ADAPTATION OF TEMPERATURE WALL FUNCTION FOR CALCULATION THE HEAT TRANSFER AT SUPERCRITICAL COOLANT PARAMETERS http://energy.kpi.ua/article/view/257268 <p><em>To date, the engineering community pays special attention to the study, research and development of methods for predicting the behavior of the coolants at supercritical parameters. This paper discusses the problem of adaptation of the existing universal or specialized tools of thermohydraulic analysis for nonlinear heat transfer problems at supercritical coolant parameters with deterioration of heat transfer. Complexities of prediction the nonlinear heat transfer at supercritical parameters of the coolant by engineering methods of computational fluid dynamics are considered. A simple way to adapt the dual-zone Kader's temperature wall function on the basis of existing probe measurements for carbon dioxide is proposed. The problem of implementation into universal packages of computational fluid dynamics (CFD), which is based on the method of choosing the reference coordinate of the near-wall zone to determine the dynamic speed and dimensionless temperature, is discussed. The example on the ANSYS CFX using shows one of the ways to create a special user procedure, which has an improved tendency to predict the axial temperature profile with deteriorated heat transfer. Calibration and validation of the obtained results on the basis of experimental investigations for vertical pipes and rod assemblies of fuel simulators is carried out in the work. The paper also discusses the features of the proposed implementation, and formed recommendations for the application and further improvement of engineering approaches to predict the heat transfer deterioration at supercritical parameters of the coolant.</em></p> V. Filonov, E. Pis’mennyi, V. Razumovskiy Copyright (c) 2022 http://energy.kpi.ua/article/view/257268 Mon, 23 May 2022 00:00:00 +0300 COMBINED METHOD OF ELECTRIC ENERGY CONSUMPTION MANAGEMENT OF PRODUCTION FACILITIES http://energy.kpi.ua/article/view/257269 <p><em>The article investigates the methods of power consumption control. It is shown that the power shortage during peak hours makes it difficult to maintain a balance between generation and consumption capacity, which leads to the need to introduce restrictions on the electrical load of industrial consumers and the development of methods and tools to control power consumption. The need to manage energy consumption is due to a number of reasons, including: 1) the significant difference between peak load and night failure in power systems; 2) insufficient regulatory capacity of thermal power plants and nuclear power plants to cover the variable part of load schedules; 3) unfavorable tendency to reduce the share of shunting capacity in power systems caused by the consolidation of power units; 4) significant capital and energy costs associated with the construction and operation of peak units; 5) technical feasibility and economic feasibility of artificial alignment of load schedules. It is shown that the following methods of power consumption control are currently known: instantaneous rate; at the ideal norm; management on the forecast value; control with the use of average power on a moving time interval (moving window method) and combined methods that use different combinations, as well as the distribution of control influence between consumers - regulators (resource allocation method). It is better to consider such a control method that provides for a larger number of managed consumers random time distribution of possible short-term emissions, their minimum absolute value, as well as more complete use by the consumer of the declared capacity or allocated power and energy limits. According to these criteria, the listed management methods are compared. Moreover, the method of instantaneous rate is implemented in control or automatic control using a signal proportional to the average power for 1, 2 or 3 minutes, the method of the ideal norm involves measuring the average power of the consumer for short periods of time (up to three minutes) and comparing this value with the declared ( or limit) power, control with prediction is that the control signal is formed as the difference between the amount of possible power and predicted at the end of the control cycle. To increase the efficiency of power consumption management, a combined control method is proposed, which is a synthesis of two known methods - control at the ideal norm and control over the predicted value of power consumption, which combines the advantages of both methods. The condition of management is maintenance of such mode of power consumption at which the set capacity is not exceeded and its set value is used as much as possible. Fulfillment of this condition is provided by working off of the restrictions set to each step of management. Due to the fact that different control steps have different control reactions to the real process, appropriate control methods are used for different steps. In the first steps, when there is enough time to adopt the optimal control effect and it can be adjusted, the control is based on the forecast value of electricity consumption, in the last steps, which have special responsibility for the control process; control is carried out by the ideal norm. Thus, this method combines the advantages of forecast management (control effect is justified) and the method of management at the ideal norm (in the last step of management, which allows optimal use of the remaining power limit and not exceed the specified value) with a priori justified order of consumers-regulators.</em></p> V.P. Kalinchyk, V.A. Pobigaylo, O.V. Meita, V.V. Kalinchyk, V.G Skosyrev Copyright (c) 2022 http://energy.kpi.ua/article/view/257269 Mon, 23 May 2022 00:00:00 +0300 TECHNICAL AND ECONOMIC DEVELOPMENT MECHANISMS OF LOCAL ENERGY SUPPLY SYSTEMS (MICROGRID) http://energy.kpi.ua/article/view/257242 <p><em>The business model of energy as a service (Energy-as-a-service, EaaS) is considered as a direction of development of the concept of 3D (Decarbonization, Decentralization, Digitalization) and the conceptual model of the Internet of energy. At the same time, EaaS is formed in the form of a "package" service model, in which the customer is provided with hardware and software and energy services. EaaS solutions should include consumption management and energy efficiency services, promote the introduction of renewable energy sources (RES) and other decentralized energy sources, and optimize the balance between supply and demand in the electricity market. EaaS is shown to be a broad term for service-driven business models with innovative potential to transform the energy industry</em></p> <p><em>To assess the specifics of EaaS application to Microgrid, the construction and operation of Microgrid as a local power system or power supply system, which is a technological complex consisting of generation facilities (energy sources), energy flexibility sources and electricity consumers, which are collected under a single management ensuring the most efficient and consumer-friendly energy supply. It is determined that the technological guarantee of the efficiency of modern Microgrid is the ability to integrate and optimally combine different energy sources and flexibility, as well as the presence of a single control loop that allows the best use of these sources.</em></p> <p><em>Smart Grid as a Service (SGaaS) based on Service-Oriented Architecture is presented. The SGaaS hierarchical architecture provides a promising three-tier architecture that includes an intelligent network level for global optimization, such as minimizing global protection or global costs, a level of coordination to maintain reliability and security in the Smart Grid, and a Microgrid level to monitor end-user device status.</em></p> <p><em>The implementation of the EaaS and SGaaS mechanisms has stimulated the development of Microgrid as a Service (MaaS) - as a service that offers the deployment of Microgrid, reducing the initial cost of investment and complexity. MaaS has been identified as a new flagship funding mechanism that allows organizations to deploy Microgrid without any prior investment, as a solution that does not require advance capital for energy consumers and focuses on results such as on-site energy. MaaS mechanisms offer customers more control over their energy needs, enabling them to increase the sustainability and reliability of their energy supply, balance energy use, achieve clean energy goals and explore other innovative products and services.</em></p> S. Denysiuk, H. Melnychuk, І. Cherneshchuk, V. Lysyi Copyright (c) 2022 C.П. Денисюк, Мельничук Г.В. , Чернещук І.С. , В.В. Лисий http://energy.kpi.ua/article/view/257242 Mon, 23 May 2022 00:00:00 +0300 PURIFICATION OF LIQUID BY ELECTROMAGNETIC FOCUSING OF IMPURITIES http://energy.kpi.ua/article/view/257275 <p><em>The article discusses topical issues of increasing the efficiency of the filtrate purification system by physical methods developed at the Institute of Energy Saving and Energy Management «Igor Sikorsky Kyiv Polytechnic Institute»</em><em>. </em><em>The work is devoted to the urgent problem of introducing the latest resource-saving, energy-saving integrated technologies for the purification of contaminated liquid media. To date, not a single theoretical base has been developed, there are only hypotheses, and there are no practical methods for calculating the magnetic treatment of water. The article is devoted to the purification by physical methods of the filtrate of domestic and industrial wastewater of industrial and domestic waste. An electromagnetic control unit was used to clean the fluid flow. Reducing the aggressiveness of the filtrate involves multi-stage control of the trajectory of impurities when they are removed from the main stream. Taking into account the properties of the experiment planning matrix, the coefficients of the regression equation were calculated, which adequately reflect the processes of liquid purification during its magnetization. Pollutant ions are charged particles. To remove them from the general flow, it is necessary to place generators on the pipeline to create developed cavitation in the fluid flow and inductance. Cavitation bubbles are internal oscillators and, releasing energy upon impact, crush and purify impurities.</em></p> <p><em>In practical water purification, insufficient attention is paid to the control of the dynamics of charged impurities by the action of external and internal forces. Magnetic treatment of an aqueous medium has a number of advantages over other physical methods: it acts on all groups of impurities; influence on both chemical and physical processes in the aquatic environment; leads to the vivacity of the environment within the enterprise due to the destruction of electromagnetic bonds between the molecules of the indium and impurities, activates the aquatic environment. The main advantage in the purification of an aqueous medium from ions of impurities is the ability to control mobile ions in a magnetic field, and therefore direct vidions of impurities per stream. Magnetic treatment of aqueous media has found its application in many industries, which, in turn, confirms the effectiveness of such devices. </em></p> О. Terentiev, A. Kleshchov, A. Vorfolomeiev, M. Sergienko Copyright (c) 2022 http://energy.kpi.ua/article/view/257275 Mon, 23 May 2022 00:00:00 +0300 DETERIORATION OF THE HEALTH OF SCHOOL AND PRESCHOOL CHILDREN BY CHANGING THE TECHNOGENIC LOAD ON THE TERRITORY OF SCHOOLS AND KINDERGARTENS http://energy.kpi.ua/article/view/257276 <p><em>The paper analyzes the state of the car fleet of Ukraine and provides statistical numbers of cars in 2020. The aim of the work is to assess the contamination of heavy metals in soils located on the territory of children's educational institutions in Kyiv, near highways, and to calculate the health risk from exposure to heavy metals. The structure of the housing stock of Ukraine by years of construction is shown. The influence of heavy metals on human health is given. Soil samples taken on the territory of the city of Kyiv at playgrounds for the content of pollutants were studied. A study has been conducted on the health risks of school and preschool children from the effects of soil contamination with heavy metals in the surrounding areas near educational institutions, where children spend most of their lives. The hydrogen index of aqueous extracts was determined, the sulfate-chloride content was analyzed, and the presence of basic cations and anions was determined. The urgency of the work lies in the problem of soil contamination in schools and kindergartens, which requires constant review. It is important to constantly monitor the soil cover within the surrounding areas, to take samples from the surface layer and at depths.</em> <em>It is also important to consider this issue when designing and building new facilities. </em></p> A. Chepel, О. Kofanova, А. Pidgornyy Copyright (c) 2022 http://energy.kpi.ua/article/view/257276 Mon, 23 May 2022 00:00:00 +0300