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  Problemele energeticii regionale

E-Journal N2(43) 2019



1 Microturbine Wave Compressor Optimal Regimes
Authors: Levihin A.A.1, Volobuev I.A.2 1 -Baltic State Technical University VOENMEH, Saint-Petersburg, Russian Federation 2 - Saint-Petersburg National Research University of Information Technologies, Mechanics and Optics (ITMO University), Saint-Petersburg, Russian Federation
  Abstract: The work is devoted to the problem of improving the efficiency of air compression in the compressor of the microturbine installation. The wave compressor in which compression occurs as in a supersonic air intake is investigated. The purpose of the study is to find the region of existence of optimal shock-wave structures at which the stagnation pressure loss in a wave compressor will be minimal. Two cases were studied: compression in a system of two shock waves of the same direction; compression in a centered isentropic wave. The research method combines a numerical experiment with an analytical study of shock-wave structures. Calculations showed that the wave compressor is more efficient than traditional blade machines, if the Mach number at the intake to it is more than 2.2. The regions of existence of shock-wave structures with a reflected discontinuity: a rarefaction wave, a shock wave, and a weak discontinuity are analyzed analytically. The weak reflected discontinuity corresponds to the highest compression efficiency. The study obtained the following most important results. A shock-wave compressor with two shock waves of the same direction can operate at the optimum mode in the range of intake Mach numbers from 2.089 to 2.46. A compression ratio of 5.76 can be obtained in this case. A centered compression wave can provide a compression ratio in one stage up to 10-12 with Mach number from 3.2 to 3.48. At higher degrees of compression, irregular shock-wave structures are formed. Keywords: microturbine, wave compressor, shock wave, isentropic compression wave, overtaking shock waves, shock waves of one direction.
  Keywords: Keywords: microturbine, wave compressor, shock wave, isentropic compression wave, overtaking shock waves, shock waves of one direction.
DOI: 10.5281/zenodo.3367056
2 Numerical Simulation of Heat Transfer in Channel with a Longitudinal Pressure Gradient
Authors: Tsynaeva A.A. Samara State Technical University Samara, Russian Federation
  Abstract: The work is devoted to the study of heat transfer in channels with a longitudinal pressure gradient. The aim of the work is to develop methods for increasing the heat transfer intensity in channels with a longitudinal pressure gradient. The goal was achieved by developing the original design of the surface intensifier, made in the form of a horseshoe-shaped dimples, as well as by conducting heat transfer studies in the channel with a longitudinal pressure gradient and dimples of various geometries and locations. It was found that a numerical solution using the k-epsilon turbulence model shows not sufficiently stable results, including the values of local heat transfer coefficients can exceed 2 ... 2.5 times their actual values for a single dimple. Moreover, the use of the k-w-sst turbulence model shows more stable results. The most significant results obtained in the work are as follows: it was revealed that the use of holes, their geometry and location have a significant effect on the heat transfer intensity in a channel with a longitudinal pressure gradient; the design of the original horseshoe-shaped dimples has been developed, the use of which allows to intensify heat transfer by 13 ... 47% depending on the Reynolds number when they are arranged in three rows in the corridor order compared to staggered hemispherical dimples; when comparing the efficiency of using the developed dimples with hemispherical holes installed in three rows in the corridor order, the heat transfer increased by 21 ... 51% when the Reynolds number changed from 3000 to 15000.
  Keywords: cooling system, turbine blades, heat transfer, pressure gradient, simulation, channel, dimples.
DOI: 10.5281/zenodo.3367076
3 Energy Monitoring of Innovative Energy Technologies of Plant Raw Material Processing
Authors: Burdo O.G.1, Gavrilov A.V.2, Kashkano M.V. 1, Levtrynskaya Y.O. 1, Sirotyuk I.V. 1, Pylypenko E.A. 1, Terziev S.G. 3 1 Odessa National Academy of Food Technologies, Odessa, Ukraine 2 Academy of bioresources and nature management «Vladimir Vernadskiy CFU» Crimea, Ukraine, 3 PAC “Enni Foods”, Odessa, Ukraine
  Abstract: The analysis of scientific works shows that the development of technology is ahead of the level of development of energy management. There are no clear comparisons of the energy efficiency of electrical technologies and heat technologies. Objective indicators of energy efficiency in various technologies of dehydration of raw materials not developed yet. In that article assumed that objective results for comparing energy efficiency in the processing of raw materials is ob-tained by the basis of system analysis of the entire energy conversion chain from fuel to fin-ished product. The purpose of the work is experimentally proving the objectivity of this hypoth-esis. To achieve this goal, it is proposing to use the indicator of the energy share of fuel in the finished product and the amount of moisture removed when burning 1 kg of fuel, which does not depend on fluctuations in energy prices, which can vary and differ for different countries. The most important result of the work is the comparison of these parameters with the data for innovative equipment samples developed by the authors. The significance of the results ob-tained is that the evaporating devices developed by the authors are not inferior in efficiency to traditional ones, and make it possible to obtain concentrates up to 90 ° brix. Thus, for fuels with an oil equivalent of 40 MJ per 1 kg, traditional dryers can remove no more than 3 kg of mois-ture, cryoconcentrators – 20 kg.
  Keywords: energy management, food production, energy efficiency, drying, cryoconcentration, microwave field, dehydration, food concentrates.
DOI: 10.5281/zenodo.3367058
4 Computational and Experimental Studies into Concentration Limits of Associated Petroleum Gas Combustion
Authors: Bachev N.L., Matyunin O.O., Bulbovich R.V., Betinskaya O.A., Shilova A.A. Perm National Research Polytechnic University Perm, Russian Federation
  Abstract: The issue of utilizing associated petroleum gas from low-yield fields in gas turbine power plants has become relevant recently. To develop universal power plants ensuring steady combustion of dissimilar in composition and highly ballast gases from different fields, reliable information on their combustion limits under real operating conditions is required. Composition analysis of as-sociated petroleum gases from various fields of the Russian Federation shows that the volume fraction of ballast components can be as high as 90 %, heavy hydrocarbons up to 10 %, hydro-gen sulfide-up to 6 %. This work is aimed to theoretical determination and experimental confir-mation of combustion concentration limits of associated petroleum gas. Another purpose is to work out recommendations for selection of the excess air ratio in the primary zone of the cham-ber at the design stage. This is achieved by theoretical determination of the air access coefficient on the upper and lower combustion limits using phlegmatization methods and experimental sub-stantiation of the computational results. The first experimental results were obtained in the pro-cess of burning petroleum gases collected directly in the fields with the volume fraction of bal-last components 26 % and 40 %. To clearly determine the presence of combustion in the cham-ber, a synchronous video recording of the process was conducted. Computational and experi-mental studies into concentration limits of associated alternated composition petroleum gas combustion resulted in some recommendations on organizing stable diffusion and homogeneous combustion in one-, two- or three-zone combustion chambers.
  Keywords: associated petroleum gases, flammability limits, excess air ratio, ballasting components, experimental setup.
DOI: 10.5281/zenodo.3367068
5 Impact of centralized and individual heating systems in residential buildings from Environmental Considerations. Case study for Chisinau
Authors: Tirsu M.S., Lupu M.L., Postoronca Sv.A. Institute of Power Engineering Chisinau, Republic of Moldova
  Abstract: The paper aims to provide argumentation of centralized district heating system use from the consideration of harmlessness for both public health and environment, in comparison with the use of individual heating units, installed in residential areas of the Chisinau municipality. Proposed goal have been reached performing the comparison on quantitative harmful emissions resulting from the operation of these two types of heating, using emissions factors, deducted from the specific consumption of thermal energy. The issue's relevance is proved by the existence of considerable number of disconnected users from the centralized heating, though last years, this trend is decreasing. As regard to new buildings, they continue to give priority to the individual heating. Statistical data provided by specialized institutions of the municipality underlines the increased share of incidents of intoxication with combustion products, namely carbon oxide, followed by poisoning from gas leaks, shingles caused by explosions in violation of the operating rules of such equipment, also registering lethal cases. New results are the determination of the difference in emission values for both cases. The importance of the obtained results is that for the generation of thermal energy in a centralized heating system using cogeneration technology, harmful emissions into the environment are 28% less than when using individual heat supply systems. This received ascertainment could serve as an important argumentation for the obvious priority of the centralized heating system in the municipality versus the use of individual units.
  Keywords: heating, centralized system, natural gas, public health, pollutant emissions, CHP.
DOI: 10.5281/zenodo.3367070
6 Influence of Cooling Tower Efficiency on Turbine Plant Economic Operation
Authors: Galatsan M.P., Kravchenko V.P., Kirov V.S. Odessa National Polytechnic University Odessa, Ukraine
  Abstract: The analysis of the world electric-energy balance revealed the advantage of steam turbine plants. An increase in their efficiency through the improvement of the initial parameters runs into difficulties associated with creation of new materials. The efficiency increase that results from the final pressure reduction requires an improvement of the circulating water supply system. The aim of this work is to determine the effect of the water-cooling tower on the electric power station profitability. This goal was reached by the creation of a mathematical model of the water-cooling tower and turbine plant with a condenser connected to each other. The calculations were made for two types of cooling tower fill packing: asbestos cement sheets and mesh elements made of polyethylene. Further, according to it, the vapor condensation temperature was determined. The latter affects the vapor discharge in the condenser, the capacity of the turbine plant and the temperature of the cooling water at the condenser output, i.e. at the cooling tower input. The novelty of this work consisted of consideration of the interaction between the cooling tower and turbine plant. Significance of the obtained results lies in the fact that, taking into account the reciprocal influence of the turbine plant and cooling tower, the efficiency of the fill packing replacement turns out to be major comparatively to the case without considering this influence. The replacement of the fill packings the half-a-year average temperature of condensation will become lower by 2.34 °С, electricity production increases by 41.72 GWh.
  Keywords: water-recycling system, mathematical model, cooling tower, turbine installation, condenser.
DOI: 10.5281/zenodo.3367064
8 Effect of Technical Parameters of Electric Low Voltage Devices of the Shop Power Supply Systems on their Reliability Characteristics
Authors: Gracheva E.I.1, Ivshin I.V.1, Gorlov A.N. 2, Alimova A.N.1 1Kazan State Power Engineering University Kazan, Russia 2South-Western State University Kursk, Russia
  Abstract: The article deals with an integrated approach to the study of the functioning efficiency of low-voltage switching devices as elements of shop networks during their operation. Based on the results of experimental studies of the contact connections of devices using a thermal imaging equipment, a new criterion is offered for the estimation of the technical condition of devices, namely, the coefficient of actual multiplicity exceeding the contact resistance under operating conditions. Its calculated numerical values for circuit breakers, contactors, magnetic starters, knife switches and batch switches are determined that allow evaluating their technical condition and operation. They also prevent the development of defects in the switching equipment and failures and make it possible to use the developed criterium for the supplemental regulation pe-riods of investigations of switching devices. An algorithm and a method have been elaborated for a comprehensive assessment of the functioning efficiency of the switching low-voltage de-vices, which allows establishing a relationship between the probability of uptime and the contact resistance of devices considering the number of switching cycles. The contact resistance is con-sidered as a random function of the number of switching cycles. The studies carried out accord-ing to the developed algorithm with the identification of the functional relationship between the contact resistance parameters and the probability of failure-free operation of the devices in-stalled on the lines of the networks allow us to evaluate the technical condition of the equip-ment. The amount of the electricity losses and characteristics reliability of the internal power supply systems can also be specified.
  Keywords: electrical apparatus, failure-free operation, reliability, electricity, power circuits, resistance of contact connections.
DOI: 10.5281/zenodo.3367062
9 Machine Training of the System of Functional Diagnostics of the Shaft Lifting Machine
Authors: Dovbysh A. S., Zimovets V. I., Zuban Y. A., , Prikhodchenko A. S. Sumy State University Sumy, Ukraine
  Abstract: The aim of the work is to increase the accuracy of functional diagnostics of a mine hoist by us-ing the method of information-extreme machine teaching with a hierarchical data structure. The tasks set forth in the work were to develop a categorical model; to carry out synthesis based on its hierarchical machine teaching algorithm for a functional diagnosis system; and to optimize the system of acceptance tolerance. Functional diagnostics necessitates the analysis of a large number of diagnostic features and recognition classes that characterize not only possible mal-functions, but also intermediate technical conditions of nodes and assemblies of a complex ma-chine. The proposed algorithm is developed in the framework of the so-called information-extreme intellectual data analysis technology based on maximizing the information ability of the system in the process of machine teaching. The main idea of the proposed method is to adapt the input mathematical description of the functional diagnostics system to the maximum reliabil-ity of diagnostic solutions in the process of machine teaching. The implementation of the pro-posed method of the information-extremal machine teaching is carried out by the example of functional diagnostics of a multi-rope mine hoist. The most significant result is the increase in the reliability of diagnostic solutions when using the hierarchical machine teaching algorithm of the functional diagnostics system as compared with the linear classifier. In addition, the crucial rules based on the optimal geometrical parameters of hyperspherical containers of recognition classes make it possible to take highly reliable diagnostic decisions in real time.
  Keywords: information-extreme intellectual technology, machine learning, information criterion, functional diagnostics, shaft lifting machine.
DOI: 10.5281/zenodo.3367060
11 Synthesis of Roller Press Rational Design for Composite Solid Fuel Production
Authors: Baiul K.V. Z. I. Nekrasov Iron & Steel Institute of National Academy of Sciences of Ukraine Dnipro, Ukraine
  Abstract: The purpose of this work is a synthesis of roller press construction for alternative fuel produc-tion from small-fraction energetic valuable raw materials. Achievement of the goal set in the work is carried out by forming a systematic approach to the search for rational design solutions for roller presses. Studies conducted on analysis basis of open information sources in the field of theoretical research, development, and implementation of press equipment for small fraction-al raw materials briquetting that used as alternative energy sources. Established, that a promising direction for the development of alternative energy is composite solid fuels production by bri-quetting method from a mixture of small fraction energetic valuable materials. Shown that roller presses use is promising for composite fuel briquettes production. Revealed the problem that currently there is no software, independent or integrated into the well-known CAD-system, that allows, taking into account briquetting process technological features, develop and simulate the life cycle of roller briquette presses. The novelty of the work lies in the fact that for the first time a systematic approach based on the use of structural-parametric synthesis and analysis has been applied for creating a rational design of a roller briquette press for the production of com-posite solid fuel. Using the proposed system approach, a new improved roller press model for the production of fuel briquettes, including composite ones, from energetically valuable small fractional raw materials having a low bulk density (0.2...0.6 g/cm3) developed.
  Keywords: alternative energy, composite solid fuel, briquettes, roller press design, structural-parametric syn-thesis.
DOI: 10.5281/zenodo.3367048
12 Estimation of Biogas Yield and Electricity Output during Cattle Manure Fermentation and Adding Vegetable Oil Sediment as a Co-substrate
Authors: Polischuk V. N., Titova L. L., Shvorov S. A. National University of Life and Environmental Sciences of Ukraine Kyiv, Ukraine Gunchenko Y. A. Odessa I. I. Mechnikov National University Odessa, Ukraine
  Abstract: The aim of this work is to increase the output of biogas and electricity power generation in biogas plants through the use of stimulating supplements in the form of vegetable oil sediment in the transition from periodic to quasi-continuous loading of the methane tank. To achieve this goal, the following tasks were solved: the biogas yield from cattle manure was defined at various temperature conditions with periodic loading of the methane tank; biogas yield was estimated during the cattle manure fermentation with the added vegetable oil sediment, using a mathematical, biogas yield was predicted for permanent loading of the methane tank. The research was carried out at the laboratory plant consisting of a methane tank useful volume of 30 liters and the gasholder of the wet type. The biogas yield was recorded for lifting of the cylinder-gauge is a wet gasholder with attached to it a scale, calibrated in centimeters. The biogas is burned on a gas stove. Calorific value of biogas was determined by its elemental composition, which was recorded by the gas analyzer. The most important results are according to the experimental researches of biogas in periodic mode, boot using this model provided prediction of biogas yield for quasi-continuous loading of the methane tank. As a result of experimental studies, it was established that during manure milling, the maximum yield of biogas was observed at 3-8 days of fermentation, and then it gradually decreased. When adding to the substrate 1.3% vegetable oil sediment the biogas yield increases and reaches a maximum value for 20 days and then it gradually decreased. The significance of the research results is that the use of vegetable oil sediment as co-substrate will allow almost three times increasing the yield of biogas and electricity generation, to reduce the payback period of a biogas plant with a capacity of 4 MW when using a green tariff to 5.1 years.
  Keywords: biogas, substrate, cattle manure, vegetable oil sediment, dry matter, methane tank, biogas plant, methane fermentation.
DOI: 10.5281/zenodo.3367054
13 Research of Lightning Protection Systems of Wind Power Plant
Authors: 1Potapenko A.N., 2Kumar Udaya, 3Shtifanov A.I., 1Soldatenkov A.S. 1Belgorod State Technology University n.a. V.G. Shukhov, Belgorod, Russia 2Indian Institute of Science (IISc), Bangalore, India 3Belgorod National Research University, Belgorod, Russia
  Abstract: The work is dedicated to the study of the influence of the wind turbine lightning protection system on the possibility of a lightning strike to the lightning rod, to the protected object and to the surface of the earth. The aim of the work is to study atmospheric electric fields for a complex object: a wind turbine, a thundercloud and a surface of the earth, in two versions - with and without a lightning protection system. This goal is achieved by constructing a mathematical model based on the Laplace equation of elliptic type and boundary conditions for calculating the electric flow function. Computational experiments over a wind turbine carried out in two basic configurations: using a rod-type lightning protection system and without it. The most significant result of the work is a mathematical model with boundary conditions that determines the rigid boundaries of the object of study and constant values at the free and symmetric boundaries for calculating the electric flow function, the method of finding the specific distribution of the lines of the flow function along the boundaries of the studied wind power installation, and the results of computational experiments. As a result, it was found that the applied numerical calculation method allows analyzing the features of the atmospheric electrostatic field near the pointed peaks. The proposed mathematical model makes it possible increasing of the efficiency of lightning protection of a power plant and can be used to simulate other objects using a rod type of lightning protection.
  Keywords: mathematical modeling, lightning protection; wind turbine; computational experiment; lines of electric force, electrostatic field.
DOI: 10.5281/zenodo.3367052
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