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  Problemele energeticii regionale

E-Journal №1(36)2018



1 Investigation of a Boiler's Furnace Aerodynamics with a Vortex Solid Fuel Combustion Scheme on Physical and Mathematical Models
Authors: Prokhorov V.B., Chernov S.L, Kirichkov V.S., Kaverin A.A. Moscow Power Engineering Institute (MPEI, National Research University) Moscow, Russian Federation
  Abstract: The important problem of developing the low-cost technologies that will be able to provide a deep decrease in the concentration of nitrogen oxides while maintaining fuel burn-up efficiency is considered. This paper presents the results of the aerodynamics study of the furnace of boiler TPP-210A on the base of the physical and mathematical models in the case when boiler retrofitting from liquid to solid slag removal with two to three times reduction of nitrogen oxide emissions and replacing the vortex burners with direct-flow burners. The need for these studies is due to the fact that the direct-flow burners are "collective action" burners, and efficient fuel combustion can be provided only by the interaction of fuel jets, secondary and tertiary air jets in the furnace volume. The new scheme of air staged combustion in a system of vertical vortexes of opposite rotation with direct-flow burners and nozzles and direct injection of Kuznetsky lean coal dust was developed. In order to test the functional ability and efficiency of the proposed combustion scheme, studies on the physical model of the boiler furnace and the mathematical model of the experimental furnace bench for the case of an isothermal fluid flow were carried out. Comparison showed an acceptable degree of coincidence of these results. In all studied regimes, pronounced vortices remain in both the vertical and horizontal planes, that indicates a high degree of mass exchange between jets and combustion products and the furnace aerodynamics stability to changes in regime factors.
  Keywords: boiler, vortex combustion, nitrogen oxides emission, direct-flow burners and jets, physical and numerical modeling of furnace.
2 Monitoring the Precession of Gas Turbine Engines Rotor Systems and Evaluating the State of Inter-Rotor Bearings
Authors: Okhtilev M. Yu., Khimenko V.I., Koromyslichenko V.N., Klucharev A.A. Zubko A.I. St. Petersburg Institute of Informatics and Automation of the Russian Academy of Sciences, Saint-Petersburg State University of Aerospace Instrumentation Saint Petersburg, Russian Federation
  Abstract: . Evaluation of the technical condition of gas turbine units, widely used in power engineering, oil and gas industry and aviation, is an important and complex scientific and technical problem. One of the most important elements that has a significant impact on the quality and reliability of the gas turbine unit is its rotor system. Dynamic mechanical interaction between the rotors and inter-shaft bearing caused by counterphase motion of the mass centers of the rotors or the precession axes can lead to a sudden failures causing bearing breakage in the two-loop gas turbine engines. It has been assumed in the paper that sudden failures are caused by accumulated, total fatigue of the bearing material arising because of shock cyclic bearing loads due to the precession of the rotors. It has been shown that the technical condition could be evaluated using vibration monitoring the precessional motion of the rotors and constructing its trajectory in the normalized, using the fatigue curve of the material, phase plane. Using the new intellectual technology of automated estimation of control object state with use of concepts “programming without programming” and the level intersection theory, vibration curves and phase trajectories were analyzed to determine the characteristics of load cycles. This makes it possible to estimate the residual resource value of the inter-rotor bearing assembly. The proposed approach possesses essential scientific novelty to the estimation of the effect of vibrations on individual units and mechanisms of gas turbine systems and can be used for creating compact field-level devices.
  Keywords: : gas turbine engine, oscillations of rotors, vibration, damageability of structural parts, life.
3 Application of Ranque-Hilsh Vortex Tube and Leontiev Tube for Cooling System of Electrical Machines
Authors: Tsynaeva A.A., Tsynaeva E. A. Samara State Technical University Samara, Russian Federation
  Abstract: The study was devoted to the development of efficient cooling systems for energy-converting machinery with static energy separators by means of numerical and experimental studies. An experimental study was used for comprehensive analysis of operation regimes of the cooling systems. The experiments were conducted on the test bench. An analysis of operation regime was carried out for two configurations: with and without Ranque-Hilsch energy separators. The study revealed 18-25 % decrease in maximum temperatures of energy-converting machinery when using Ranque-Hilsch separators along with basic heat pipes. Furthermore, Ranque-Hilsch energy separators provided higher temperature drop in the heat pipe. The numerical model was based on the equation of state and conservation equations for mass, energy, and momentum. The numerical study was carried out using the RANS approach with k-omega SST model of turbulence. Free open-source software platform Code_Saturne was used for simulation. The developed numerical model was verified by comparison of the obtained results with adopted experimental data. Additional verification was carried out by comparison with a criterion-oriented calculation of heat exchange. Obtained simulation results showed heat transfer intensification up to 22 % (at a distance of 0-1.45 calibers from the throat of the nozzle) compared to a cylindrical channel. At a distance over 7 calibers, heat transfer efficiency decreases and appears to be up to 24 % lower compared to a cylindrical channel. Based on results of experimental and numerical studies, a potential of increase of energy efficiency of cooling systems for energy-converting machinery when using energy separators has been assessed.
  Keywords: cooling system, electrical machines, heat transfer, turbulence, simulation, energy separator, Ranque-Hilsh vortex tube, Leontiev supersonic tube.
4 Calculation Features of the Combined Schemes of Cooling of Refrigeration UnitsCondensers
Authors: Fot A. N. Omsk State Technical University Omsk, Russian Federation
  Abstract: Modern requirements for energy saving and decrease in environmental pollution demandrevisingclassical technical and technology solutions of refrigeration unit production. Composite cooling application of refrigeration units allows condensers to reduce pollution of fresh waters, to reduce consumption of electric energy, to reduce condensation pressure, to use natural cold of the environment. In this work approach to thermal and mass balance determination of the refrigeration units with the combined cooling of condensers with intermediate discharge of liquid coolant between condensers of waterand air cooling is offered. Definition of an enthalpy before a throttling expansion (mix of the sated and overcooled liquid after condensation knot) taking into account dryness degree is specified. For influence assessment of this feature the numerical analysis on the example of the refrigeration units of the freon refrigeration units is carried out. Made change of refrigerating coefficient for the refrigerator with the combined cooling of rather classical scheme of condensation to 2.5%. Change of loadingson knot of condensation made 2.2%, on the evaporator of 2.5%. For calculation and the choice of the capital equipment of the refrigeration unit these changes will not exert decisive impact, and for regulation of refrigeration unit operating modes will have significant effect, especially at the large enterprises of oil processing branch and large transport objects. The received specification of refrigeration unit calculation is used in program modules of refrigeration unit calculation with the combined cooling of condensers and allowed to carry out the qualitative parametrical analysis of its work.
  Keywords: combined cooling, condensing unit, water and air cooling, energy savings, mathematical model, chiller.
5 Modeling of Installations with a Rotary Kiln for Thermal Decontamination of Wastes
Authors: Krot O.P.,1 Rovenskyi O.I.2 1Kharkov National University of Civil Engineering and Architecture 2North–East Scientific Center of the National Academy of Sciences of Ukraine Kharkov, Ukraine
  Abstract: The object of the study is a plant for incineration of solid wastes in a rotary kiln with an afterburning chamber and thermal catalytic emission purification. The aim of the study was to determine the rational layout of the solid wastes loading system and the location of the burner during combustion in the system - a rotary kiln and an afterburning chamber. The results of simulation countercurrent and concurrent gas flow and wastes in the form of temperature gradients in the rotary kiln and afterburner chamber are presented. It is found that in the initial part of the rotary kiln, a temperature of more than 1000 °C is created on its lower surface, almost one-third of the length of the furnace (2.5-3 times more than in the concurrent mode). In a zone close to unloading, the temperature is minimal (less than 100 °C), therefore, the slag does not tolerate heat from the furnace, it has time to cool down. Criteria for the efficiency of the rotary kiln have been proposed: the length of the section where the maximum combustion temperature is reached, the length of the section before discharge of the slag, the temperature of the slag. A more efficient configuration for all the criteria is one that ensures the counter movement of debris and gas. To effectively use the volume of the afterburner chamber, the burners must be located at the maximum distance from each other. The outlet flue must also be as far from the burners as possible.
  Keywords: wastes incineration, rotary kiln, waste to energy, municipal wastes, modeling, combustion modeling, movement of gas flow
6 Microwave Energy as an Intensification Factor in the Heat-Mass Transfer and the Polyextract Formation
Authors: Burdo O.G.1, Syrotyuk I.V.1, Alhury U.2, Levtrinska J.O.1 1Odessa National Academy of Food Technologies Odessa, Ukraine 2 Aleppo, Syrian Arab Republic
  Abstract: The prospects of using the specifics of food raw materials structure for organizing mass transfer in the processes of extraction and dehydration has been shown. Authors studied in depth, in comparison with existing studies, selective effect of microwave energy on moisture in food raw materials. It has been shown that targeted energy supply to nanoscale elements in food raw materials is the basis for the creation of innovative technologies. The instrument for controlling such processes can be an electromagnetic field. A successful combination of the structure of food raw materials and field parameters can initiate a powerful flow of target components from product volume. Authors have analyzed driving forces of the effect of "barodiffusion". Mechanisms and stages of the processes of components transfer from plant raw materials were proposed for the gradientless supply of electromagnetic energy. The technique, stand and results of visualization of the effect of "barodiffusion" were presented. Created stand includes an electromagnetic energy generator equipped with a digitized endoscopic camera shielded from the field, which allowed the authors to get a visualization of the phenomenon for the first time. The results of experimental studies of extraction and evaporation processes in the microwave field during the processing of food systems of different structure were considered: alcohol-water-containing, dispersed and homogeneous. Obtained results testify to the prospects of introduction of equipment using the effect of "barodiffusion" in the technology of cognac spirits, oils, polyextracts, essences, food concentrates, phytopreparations.
  Keywords: microwave assisted extraction, vacuum evaporation, nanotechnology, the effect of "barodiffusion", technology of targeted energy delivery, modeling.
7 Management of Energy Flows in Low-temperature Separation Units
Authors: Trishyn F.A., Trach O. R., Orlovskaya Yu. V. Odessa national academy of food technologies Odessa,Ukraine
  Abstract: The aim of this work is to study the effect of medium and low power ultrasound on the crystallization and separation processes. A thesis about the importance of using thermal energy converters in separation units has been suggested. The prospects of desalination freezing units and ways of their improvement have been justified. Based on the system analysis, the energy flows in an ice recycling facility have been considered. For the first time, the overall energy efficiency estimation technique based on the hypothesis of direct and reverse energy flows has been proposed. The new results on the effect of ultrasonic fields on the separation and crystallization process have been obtained. It has been proved that the use of ultrasonic field is effective in controlling the energy flows during block freezing. It has been established that the salt content in the ice block is reduced by 2-3 times. The relationship between the ice block separation kinetics and the power and frequency has been determined. The similarity theory methods have been used to summarize the experimental data obtained. The criterion models have been presented to calculate the block porosity and the filtration rate. It has been established that the Euler wavenumber modified by the authors successfully generalizes the databases of the experimental findings. Using the numerical simulation methods, the thermal field in the block which depends on its porosity has been established. The results of the simulation have been presented in the form of a nomogram.
  Keywords: modeling, crystallization, porosity, concentration, temperature, heat transfer
9 Method for Determining the Operating Characteristics of Frequency Converter Using Interphase Power Controller Technology
Authors: Kaloshin D.N. Institute of Power Engineering Chisinau, Republic of Moldova
  Abstract: The object of the study is a frequency converter based on IPC technology. The purpose of the study is to determine the device's performance characteristics by means of a mathematical apparatus describing the area of existence of operating modes for active and reactive power. On the basis of combinatorial laws, variants of non-repeating states of thyristor keys were obtained. The initial phases of active and reactive power components are determined by varying in accordance with the cosine law with two non-repeating combinations of key switching on each pair of conjugate reactive elements. The input of two constants made it possible to simplify the arguments influencing the magnitude and direction of the transmitted power by the device. A comparative analysis of the regime parameters and the characteristics obtained with the help of the simulation model and calculated by the proposed method confirms the identity of the results. The error of the method fluctuates between 0.5% and 1.5%. The developed method made it possible to determine a number of unique variants of the transmitted power level when adjusting the angle in the range . This allows to adjust the magnitude and direction of the transmitted power when "sliding" or slow and arbitrary frequency changes. Thus, the proposed method made it possible to determine with a high degree of accuracy the domain of existence of the regime parameters with the construction of switching diagrams of keys to maintain an ordered unidirectional power flow with frequency matching by the device under study.
  Keywords: multimodular frequency converter, interphase power controllers (IPC), power flow.
10 Investigation of Technological Operations Affecting the Determination of Concentration of Ionol Additive in Insulating Oil in High-Voltage Equipment
Authors: Korobeynikov S.M.1, Lyutikova M.N.2 1Novosibirsk State Technical University Novosibirsk, Russian Federation 2Federal Grid Company of Unified Energy System, Noyabrsk, Russian Federation
  Abstract: Ionol oxidation inhibitor level control is included into normative indicators list for diagnostics of internal insulation condition of any oil-filled high voltage device. Concentration of oxidation inhibitor in dielectric liquid should be from 0,08 % to 0,40 % mass. Power supply network chemistry laboratories use such methods as spectroscopy, spectrometry, chromatography and many others. Russian insulation service specialists use the method of ionol concentration measurement in oils based on gas-liquid chromatography. In the first place it is related to the fact that gas chromatographs are installed for several tasks, including definition of inhibitor’s mass concentration. However, as practice shows, the use of this method for additive analysis, especially in old acidified mineral oils is linked to some difficulties. The aim of this work is identify technologic faults that may occur during definition of ionol inhibitive additive in dielectric liquid with gas-liquid chromatography method, and, as a consequence, may lead to incorrect calculation of ionol additional concentration to oil, necessary for its antioxygenic properties maintenance and high insulation quality provision during high voltage device functioning. The object of the research is insulating oil with more than 35 years’ operating cycle, presenting a complex multiplex matrix of hydrocarbons and oxygenates preventing reliable determination of ionol additive with gas-liquid chromatography method. Executed researches show that the main input into “correct” final result obtention during calculation of additional additive concentration was made by such technological operations as water content in extractant and technology of sample introduction into chromatograph’s evaporation tank.
  Keywords: internal insulation, liquid dielectric, mineral oil, oxidation inhibitor, additive, ionol.
11 Transformer-Based Power Conversion System with Synchronous Adjustment of Modulated Inverters
Authors: Oleschuk V. Institute of Power Engineering Kishinau, Republic of Moldova
  Abstract: . Purpose of this work – dissemination of specialized schemes of space-vector modulation for synchronous adjustment of multi-inverter system with power transformer. Multi-winding power transformer systems are between perspective topologies of power conversion systems. Parameters and characteristics of transformer-based ac drives depend largely on the used methods and techniques of control and modulation. These medium-power and high-power systems are characterized by relatively low switching frequency of inverters. Modification of algorithms of space-vector modulation for transformer-based system with several converters allows providing an improvement of spectral composition of winding voltages of the system. Set of control functions includes in this case special correlations for continuous determination of parameters of control signals for this triple-inverter system. Simulation of modulation processes in this structure of system has been executed for different modes of its operation. Analysis of harmonic composition of basic voltage waveforms has been executed. Areas of the rational use of continuous and discontinuous versions of modified algorithms of modulation have been established. It has been found that for the analyzed transformer-based system it is reasonable to use algorithms of continuous modulation at lower and medium output frequencies of the system, and at higher output frequencies, the use of algorithms of discontinuous modulation makes it possible to provide the better spectral composition of the winding voltage. Advanced harmonic composition of spectra of the corresponding voltages allows providing increase of efficiency of operation of this topology of power conversion systems.
  Keywords: inverter, ac drive, pulse-width modulation, voltage waveform, voltage harmonic composition.
13 Pulsed Nonlinear Automatic Control System for Guidance of a Caterpillar Tractor Unit in Vineyards
Authors: Sit M.L. Institute of Power Engineering Kishinau, Republic of Moldova
  Abstract: The automatic guidance systems of tractors for soil cultivation in vineyards have attracted the attention of researchers since the second half of the twentieth century. The purpose of this paper is to investigate the driving quality of an automatic guidance system (AGS) for a caterpillar tractor unit (CTU) consisting of a crawler tractor and a vineyard plow and having the orientation system by grapes stamps. Compared with the known works (in which GPS, LIDAR, and video cameras are used for orientation), the proposed system is the least expensive. For this, the existence of stability of the AGS as a whole in the range of operating speeds of the unit was proved. The dynamic model of the vineyard plow was verified on a three-point hitching system of the tractor, field tests of the AGS were carried out, which confirmed the results of theoretical studies, and suggested directions for further research. The shape and parameters of the modulation characteristic (MC) of the pulse-width modulator (PWM) of the AGS control system, the rational values of the hydraulic drive speeds of the sequential control mechanism of the clutch of the turn and the crawler tractor belt brake, were established, depending on the slope angle and the speed of the unit, ensuring agrotechnical requirements for driving. New solutions, in comparison with the known ones, are the ways of forming the MC of PWM using a new design probe and the associated driver MC of PWM.
  Keywords: automatic guidance, caterpillar tractor, pulse-width modulation, control, mechanical probe, field tests.
14 Mobile Autonomous Reconfigurable System
Authors: Pavliuk N.A., Krestovnikov K.D., Pykhov D.E. St. Petersburg Institute for Informatics and Automation of Russian Academy of Sciences SPIIRAS St. Petersburg, Russian Federation
  Abstract: The object of this study is a multifunctional modular robot able to assemble independently in a given configuration and responsively change it in the process of operation depending on the current task. In this work we aim at developing and examining unified modules for a modular robot, which can both perform autonomous movement and form a complex structure by connecting to other modules. The existing solutions in the field of modular robotics were reviewed and classified by power supply, the ways of interconnection, the ways of movement and the possibility of independent movement of separate modules. Basing on the analysis of the shortcomings of existing analogues, we have developed a module of mobile autonomous reconfigurable system, including a base unit, a set of magneto-mechanical connectors and two motor wheels. The basic kinematic scheme of the modular robot, the features of a single module, as well as the modular structure formed by an array of similar modules were described. Two schemes for placing sets of magneto-mechanical connectors in the basic module have been proposed. We described the principle of operation of a magneto-mechanical connector based on redirection of the magnetic flux of a permanent magnet. This solution simplifies the system for controlling a mechanism of connection with other modules, increases energy efficiency and a battery life of the module. Since the energy is required only at the moment of switching the operating modes of the connector, there is no need to power constantly the connector mechanism to maintain the coupling mode.
  Keywords: modular robotics; servo drives; connector; magnetic circuit; magneto-mechanical connector.
16 Forecast Model of Russia’s Gross Domestic Product Depending on Financial Instruments of Trade in Energy and Commodities
Authors: Samkov T.L. Novosibirsk state technical university Novosibirsk, Russian Federation
  Abstract: Methodology of forecasting the gross domestic product (GDP) growth for complex socio-economic systems is projected on economic conditions of the Russian Federation. The most important factors affecting GDP change, development of a GDP forecast econometric model for the Russian economy and the methodology of the model use are identified. The model is used as a source of information necessary for the analysis of territorial multi-sectoral objects (ATMO) model which we developed. ATMO model is the model of planning regional sectoral production systems of independent corporate participants and can predict their behavior utilizing game approach. Non-systemic "signal" information (GDP growth rate) is necessary to change the strategies. The factors for predicting are the primary and secondary financial instruments of trade in energy and raw commodities. The principle of behavioral imitation is introduced for the first time in relation to a class of such tasks. Technology of decisions making corresponds to the knowledge of managers and officials rather than to that of analysts. The forecast model reflects the "ordinary" view of mentioned decision makers on the nature of GDP dependence on trade in specific goods (oil, gas, grain, gold, silver, copper, etc.). Almost any company leader will be able to use this set to forecast GDP as guidelines for further development of the enterprise. The ATMO model makes it possible to influence the economy to achieve macroeconomic goals and gives the opportunity to increase the available volumes of energy resources for export, e.g., for functioning of the emerging gas hub in EU.
  Keywords: gross domestic product, econometric model, energy, commodity, derivative, behavioral simulation.
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