Global Energy

RAR RUS 5-18 Filin A. Golubkov Valentin Optimization of computational algorithms for deter-mining the thermal state of turbine generators active parts This paper studies computational algorithms for the thermal state of turbine generators active parts. There are well-known algorithms, based on ventilation substitution schemes, which do not allow considering the nature of the flow of the cooling medium in detail, but form averaged initial data for the formulation of the heat transfer problem. Resource-intensive CFD calculations are also used to simulate a full ventilation path. Here, an applied hybrid model is proposed, combining advantages of the described approaches and taking into account the return coupling between equivalent resistance change and mass flow of the ventilation path elements in multivariate simulations. This model allows us to increase the calculation speed and the results accuracy. The proposed approach is verified by comparing the simulated results with the experimental data. 10.18721/JEST.27401 621.313.322-81 ventilation path CFD heat transfer turbine generator optimization https://engtech.spbstu.ru/article/2021.118.1/ Filin%2C-Golubkov%2C-Shishkina.pdf

RAR RUS 19-29 Bodrenkov Evgeniy B-7916-2013 6601971248 0000-0002-1173-8727 Peter the Great St. Petersburg Polytechnic University, Russia Korovkin Nikolay nikolay.korovkin@gmail.com

Russia, 195251, St.Petersburg, Polytechnicheskaya, 29

Selitrenikov Dmitriy Identification of the composition of multi-element non-linear load by measuring the current and voltage at its input The paper presents an approach for identifying the composition of a multicomponent non-linear load with the aim of identifying its typical nonlinear elements. The proposed approach allows us to separate the linear component of the load from the nonlinear and determine the num-ber of the non-linear elements of each type in the load given their types are known beforehand. The information obtained can be used in resolving disputes about damage caused to the equipment of the electricity supplier or the consumer in case of inappropriate power quality. The approach can be used to control the load of the consumer without interfering with their electrical facilities. Identification is based on measurements at the input of the load. The initial data are the harmonic composition of the input load current and information about the typical elements. The solution includes decomposing the harmonic composition of the input current based on the input current vectors of different types of nonlinear loads. We also estimated the method error for inaccurate measurement of the input current, as well as for the use of nonlinear elements with close current-voltage characteristics. We intend to find the possibilities of increasing the accuracy of the method. 10.18721/JEST.27402 537.311.6 power quality non-linear load Fourier transform spectral selectivity harmonica least-squares deviation method electric-power engineering liability https://engtech.spbstu.ru/article/2021.118.2/ Bodrenkov%2C-Korovkin%2C-Selitrenikov.pdf

RAR RUS 30-41 Ivanov Ivan Glivenko Dmitrii Hojamov Akhmet Randomization method application in numerical simulation of electrophysical processes in metallized film capacitors Numerical simulation of physical processes is an effective design method of new energy-intensive electric capacitor types. Polymer film capacitors are widely used in modern power equipment, because of their extremely high value of specific energy. As a rule, numerical simulation uses ideal geometric objects and physical conditions. This fact explains some difference between experimental and simulation results. This paper presents the application of randomization method in the study of electrophysical processes in metallized film capacitors’ electrodes. As an example of possible application, the numerical model of segmented capacitors electrodes’ electrothermal destruction during self-healing process is presented. The obtained results of numerical simulation have a statistical dispersion that correlates with the experimental data. Suggested randomization method is an addition to the research carried out in this scientific direction. 10.18721/JEST.27403 621.319.4 metallized film capacitor; segmented electrodes; self-healing; numerical simulation; randomization method https://engtech.spbstu.ru/article/2021.118.3/ Ivanov%2C-Glivenko%2C-Hadzhamov.pdf

REV RUS 42-67 Mannanov E. About dielectric materials with high thermal conductivity for electrical insulation systems of high-voltage electric machines: a review of domestic and foreign literature The article presents a review of domestic and foreign sources relating to problems of improving thermophysical parameters of polymer materials, impregnating varnishes, electrical insulating tapes and composite materials used as electrical insulation in high-voltage equipment, while retaining their electrophysical, mechanical and technological properties. The author reviewed publications for the past 20 years published by the authors from Russia, USA, Germany, France, Great Britain, Japan. The study used the Russian Patent Office database, Orbit database, European Patent Office database, Eurasian Patent Office, Patent Cooperation Treaty and the Internet. In the course of the engineering and technical analysis, the known data published in the open scientific and technical press were summarized, the level of technical development was assessed and highlighted. The results include a comparative analysis of the characteristics of polymer materials filled with highly heat-conducting dielectric particles and a list of the main trends in the development of the research object. 10.18721/JEST.27404 621.315 electrical insulating material stator winding mica tape high thermal conductivity dielectric tape composite material https://engtech.spbstu.ru/article/2021.118.4/ Mannanov.pdf

RAR RUS 68-84 Sakhno Ludmila lsahno2010@yandex.ru Sakhno Olga Olasahno@mail.ru Krylov Mikhail Method for calculating and measuring active powers and losses in flash-butt welding transformers The paper considers three-winding transformers with two parallel-connected sections of the primary winding and one secondary winding. This design is used in flash-butt welding transformers. The article provides a method for calculating currents, active power and losses in the windings, based on the equivalent circuit of a multi-winding transformer. The equivalent circuit of a three-winding transformer is based on its replacement with two two-winding transformers. All parameters of the equivalent circuit can be measured. The relationship between active power and winding losses has been established, which underlies the indirect method of measuring winding losses. The analysis of the accuracy of the technique was carried out on a model FEM transformer. To clarify the technique, vector diagrams have been constructed, showing, in particular, that the active power in one of the primary windings during a short circuit can be negative (the angle between the current and voltage vectors in the winding exceeds 90°). Relationships between the parameters of two-winding transformers in this case are obtained. The results of calculating the currents and active powers in the three-winding transformer of the KSS-04 welding complex for pipe welding are in good agreement with the measurement results. 10.18721/JEST.27405 621.314.225 three-winding transformer equivalent circuit active power magnetic leakage flux mutual inductance on leakage flux https://engtech.spbstu.ru/article/2021.118.5/ Sahno%2C-Sahno%2C-Krilov.pdf

RAR RUS 85-95 Kortikov Nikolay n-kortikov@yandex.ru Optimization of the cooling system of the nozzle blade of an energy gas turbine The system of convective-film cooling of the first stage nozzle blade of the gas turbine is optimized on the basis of a unified information environment with the inclusion of an effective optimization method using the response surface, an indirect optimization algorithm based on the principles of self-organization (IOSO). The paper proposes a mathematical model for calculating the wall temperature during convective film cooling based on empirical data to determine the heat transfer coefficient and the efficiency of film cooling. A single code has been developed that allows combining a FORTRAN program for calculating the cooling depth of a perforated plate and an IOSO optimizer. The calculation results indicate a decrease in the relative flow rate of the cooler (from 7% to 6%) due to the newly obtained distributions of the cooler flow rate, the diameter of the blow holes and the pitch of the perforation system (with an average cooling depth of 0.65). Thus, it is possible to increase the power of the gas turbine by 160 kW. 10.18721/JEST.27406 532.529:536.24 energy gas turbine; nozzle blade covective-film cooling system mathematical model optimization mass flow https://engtech.spbstu.ru/article/2021.118.6/ Kortikov.pdf

REV RUS 96-105 Patil Suraj Constrained groove pressing of aluminium alloys – a review Constrained groove pressing (CGP) is a modern process for the formation of ultrafine grain in metallic sheets with high mechanical properties. During CGP, the sheet metal are subjected to repetitive corrugating and straightening under the plane strain deformation condition by utilizing alternate pressing with the asymmetrically grooved dies and flat dies. This leads to an increase in the degree of plastic strain of the sheet metal without changing its original dimensions. CGP can effectively refine the grain structure to a sub-micron level. Materials processed by CGP have a very high strength, high hardness and many other required properties. This review focuses mainly on CGP process technology, especially the number of passes, as well as the study of microstructure changes. Most of the scientific results were obtained experimentally. 10.18721/JEST.27407 669 CGP Microstructural change mechanical properties https://engtech.spbstu.ru/article/2021.118.7/ Patil-(na-angl_).pdf

RAR RUS 106-116 Vishniakov Pavel Peng Shengjie Maximov Maxim maximspbstu@mail.ru Synthesis and electrochemical characteristics of nanocoatings of lithiated tantalum oxide solid electrolyte One of the most promising technologies for increasing the safety and durability of solid-state batteries (SSB) is nano-coating between electrodes and electrolytes. The paper presents the results of a detailed microscopic and electrochemical analysis of multilayer thin films. The investigated multilayer structures consist of a two-layer system of an amorphous Li-O layer and a Ta-O layer obtained by atomic-layer deposition on Si and steel substrate. The results show that the growth rate of the films is 0.21 nm/supercycle, which corresponds to the theoretical one under the given synthesis conditions. The X-ray diffraction pattern shows that the Li-O and Ta-O layers are X-ray amorphous with a small content of Ta2O5 nanocrystallites. The ratio of the Ta:O components in the films obtained was 1:4, which is close to the theoretical LiTaO3. However, no mixed oxides of the Li-Ta-O system were found, which indicates that the film is multilayered. Analysis of cyclic voltammograms showed no interaction with liquid electrolyte in the range of cathode potentials (4.3–3.0 V). In addition, the coatings do not significantly contribute to the electrochemical capacity so that they can be used as a functional layer between solid electrolytes and electrodes in SSB. 10.18721/JEST.27408 661.1 atomic layer deposition multilayered structure solid electrolyte functional layer solid-state batteries https://engtech.spbstu.ru/article/2021.118.8/ Vishnyakov%2C-Pen%2C-Maksimov.pdf

REV RUS 117-123 Sutar Praveen A short review of vibration isolation using various insulating materials As for the increasing dependability of man on the machine, it seems necessary to strive for improvement of the performance of machines given that the dependent inputs are not changed drastically. In mechanical engineering terms, we are accustomed to working towards increasing the efficiency of a prime mover or core machine setup by developing methods to reduce wastage of energy, and performance reducing factors can be eradicated. In machines vibration is the underlying factor that complies to carry out periodic maintenance, not working up to the full potential of the prime movers, limiting the working and output of the mechanical forces and thus resulting in reduced performances. This paper provides brief review of the effects vibration has on the performance and how isolating it can result in increased efficiency and performance. 10.18721/JEST.27409 620 Vibration Isolation Mounting material https://engtech.spbstu.ru/article/2021.118.9/ Sutar-(na-angl_).pdf

RAR RUS 124-131 Demidov Alexander ph-chem@ftim.spbstu.ru Markelov Iliya Thermodynamics of iron oxides reduction by carbon monoxide in the presence carbon The paper presents the results of a calculation of the standard Gibbs free energy of the reactions of iron oxides reduction by carbon monoxide in the presence of carbon in the temperature range of 900–1600°K. A comparative thermodynamic analysis is made for the following reactions: interaction of iron oxides with carbon monoxide with the formation of carbon dioxide; interaction of iron oxides with carbon to form carbon monoxide, carbon dioxide; interaction of iron oxides with carbon and carbon monoxide to form carbon dioxide. The calculations are based on the principle of independence of the reactions in the system. The calculations of the change of the standard Gibbs free energy of reactions are made per mole of atoms of the initial substances (per mole of the system). It is shown that at temperatures higher than 1000–1100°K the reduction of iron from iron oxide(III), iron oxide(II,III) and FeO1+x’ occurs due to interaction with carbon monoxide in the presence of carbon. In the temperature range of 400–800°K, iron can be reduced from oxides through the interaction with carbon monoxide only. 10.18721/JEST.27410 669.2 thermodynamics iron oxides carbon monoxide carbon reduction https://engtech.spbstu.ru/article/2021.118.10/ Demidov%2C-Markelov.pdf

RAR RUS 132-144 JSC "Atomproekt" Rogozhkin Vladimir Gorynin Vladimir z1dehy97@mail.wplus.net A-9655-2014 7007045735 0000-0001-7385-147X Peter the Great St. Petersburg Polytechnic University, Russia Kondrat'ev Sergey petroprom2013@yandex.ru

Russia, 195251, St.Petersburg, Polytechnicheskaya, 29

Mischin Evgeniy B. Kolenov Evgeniy V. Shevoldin A. Cooler against overheating of Australia The paper proposes a principle and presents an aerothermal system Land Coolers (cooler) for the correction of abnormal warming (climate) of the regions of Australia. The system generates high-altitude technogenic clouds over problem areas, using atmospheric moisture in the waters of the near seas, excessive thermal energy consumption of thermal and nuclear power plants, and the prevailing flow of high-altitude tropospheric winds. The cirrus-type umbrella cloud generated by the aerothermal cooler into the troposphere weakens the solar load and overheating of the problem areas of Australia. For the formation of high-altitude clouds over 6 km, the system employs a vertical steam-air jet from a coastal energy facility modified by an injector. It forms optically dense clouds of the upper and middle tier of the troposphere with an area of up to 100 thousand square kilometers, protecting the surface air from overheating and ensuring the availability of the territories of Australia to Pacific Ocean and Indian Ocean rains. 10.18721/JEST.27411 551.583 aerothermal system Land Coolers (cooler); regional correction of abnormal warming (climate); high-altitude technogenic cloud cover of the cirrus type; troposphere; thermal energy saving; heat-saving power plants; atmospheric moisture of the sea area https://engtech.spbstu.ru/article/2021.118.11/ Rogozhkin.pdf

RAR RUS 145-158 Al-Mashhadani Ali M. Pershin Vladimir Relationship between the shape of particles of initial graphite and graphene plates during liquid-phase shear exfoliation Graphene-based materials are very interesting due to their excellent chemical, physical and mechanical properties, which make them extremely useful as preferred materials in various industrial applications. Liquid-phase exfoliation of graphite makes it possible to obtain graphene with a low level of defects. Many researchers have determined the size of graphene plates obtained by liquid-phase exfoliation of graphite, but there are no studies that analyze the relationship between the shape of the particles of the original graphite and graphene plates. This article analyzes the results of studies of the shape and size of parts of the original graphite and graphene plates. It was found that the shape of the initial graphite particles can be represented as an ellipsoid with different values of the semiaxes in three mutually perpendicular directions (length, width, thickness). Approximate ratios of these dimensions have been found, which can be used in calculating the process of liquid-phase exfoliation of graphite. 10.18721/JEST.27412 620.3 particle shape; nanoplates; number of graphene layers exfoliation length of nanoplates https://engtech.spbstu.ru/article/2021.118.12/ Al-Mashhadani%2C-Pershin.pdf