Energy and automation

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EISSN : 2223-0858
Total articles ≅ 282
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A. Kushnirenko, SEPARATE DIVISION OF THE NATIONAL UNIVERSITY OF BIORESOURCES AND NATURE MANAGEMENT OF UKRAINE ", V. Pryadko, O. Sinyavsky, NIZHYN AGRICULTURAL INSTITUTE", Zhytomyr National Agroecological University, National University of Life and Environmental Sciences of Ukraine
Energy and automation pp 97-106; https://doi.org/10.31548/energiya2021.02.097

Abstract:
The research is devoted to the study of the behavior of the generalizing magnetization vector in the seeds of agricultural crops under the action of longitudinal constant and transverse alternating magnetic fields by the method of nuclear magnetic resonance. Based on the theoretical studies, the value of the average magnetic susceptibility per unit volume of seed χ and the value of the magnetization vector were determined. For the system of microparticles of cells of plant origin, the average magnetic susceptibility per unit volume of seed is χ = 2.1 · 10-5, and the magnetization vector M=13.125 mA/m at a longitudinal constant magnetic field strength H = 625 A/m. When a weak transverse alternating magnetic field is superimposed on the frequency, the oscillation frequencies of the magnetization vectors M coincide with the field frequency, which is a condition for the occurrence of magnetic resonance. The longitudinal magnetization vector during the transition from the ground state to the excited state (resonant) describes a trajectory in the form of a spiral on the surface of the sphere. A mathematical model for a biological system taking into account the Earth's magnetic field is built. It is established that for the technology of pre-sowing treatment of seeds of agricultural crops, the inductor, which creates a constant magnetic field, must be located so that the vector of the constant magnetic field of the inductor coincides with the vector of the Earth's magnetic field. Keywords: bioenergetic resonance, pre-sowing treatment of crop seeds, direct magnetic field, alternating magnetic field, longitudinal and transverse relaxation
M. Prokopov, Sumy State University, S. Sharapov, Yu. Merzlyakov, D. Gusev
Energy and automation pp 39-51; https://doi.org/10.31548/energiya2021.02.039

Abstract:
The expediency of the implementation of the principle of steam thermal compression to improve the energy efficiency of sources of electricity and heat supply of small heat power engineering is substantiated. The results of thermodynamic analysis and numerical optimization of the parameters of the compressor steam-turbine cycle of a small cogeneration power plant are presented. A jet step-down thermotransformer has been tested - as an alternative to traditional boiler heating. On the basis of the conducted thermodynamic analysis, a new combined cycle of a step-down thermotransformer has been developed, which ensures efficient conversion of the supplied energy (mainly in the form of fuel heat) into the heat carrier flow of the heat supply system with the required temperature level 50 ... 90 °C). The fundamental difference between the considered thermal transformer and steam compressor heat pumps is the replacement of a mechanical compressor with a steam thermocompressor module (STC-unit). The working process in the STK-module is realized by using the liquid phase of the refrigerant, which boils up during expiration, subcooled to saturation, as an active medium of a jet compressor. Injection of steam from the evaporator is provided due to the fine-dispersed vapor-droplet structure formed in the outlet section of the active flow nozzle. A program for the numerical study of the working process of a step-down thermal transformer was prepared and tested, on the basis of which multivariate calculations were carried out. On the basis of computational studies, the area of achievable indicators of the proposed heat supply system has been established; the area of initial operating parameters corresponding to the maximum values of the conversion coefficient and exergy efficiency was determined; comparative indicators of the main parameters of the investigated thermal transformer on various working substances in the range of operating modes as a heat pump or a refrigerating machine were obtained. Key words: workflow, steam thermocompressor, step-down thermotransformer, energy efficiency, heat pump mode
N. Fialko, Institute of Engineering Thermophysics of NAS of Ukraine, A. Stepanova, R. Navrodskaya, S. Shevchuk, G. Sbrodova
Energy and automation pp 5-16; https://doi.org/10.31548/energiya2021.02.005

Abstract:
The results of operating parameters optimization of the air-heating heat-recovery exchanger of complex heat recovery system of a gas-fired boiler designed for heating water and blown air are presented. Air heating in this heat-recovery exchanger is realized by deep cooling of the waste exhaust gases, that is, with a change in their moisture content during the heat recovery process. The possibilities of using a complex technique based on the structural-variant method and exergy analysis methods for the optimization of the heat-recovery exchanger are analyzed. The developed structural scheme of the boiler plant with identification of input and output exergy streams for all elements of the installation is presented. The change of exergy losses in this heat-recovery exchanger has a rather strong effect on the change of the whole heat recovery system efficiency is established. Thus, the optimization of heat-recovery exchanger operating parameters of is a necessary condition for increasing the efficiency of heat recovery in general. The choice of multiplicative exergy efficiency criteria used as target functions of operating parameters optimization of the investigated air-heating heat exchanger is substantiated. The obtained dependences of exergy efficiency criteria on the operating parameters of the heat-recovery exchanger, such as the ratio of the Reynolds numbers of exhaust gases and air and the ratio of the initial and final moisture content of exhaust gases, are analyzed. It is established that the minimum values of the efficiency criteria, which corresponds to the maximum exergy efficiency, is observed in the range of values of the ratio of the initial and final moisture content of exhaust gases in the range from 2.4 to 3.0. It is shown that at a value of the specified ratio of 2.7, the exergy efficiency of the investigated heat-recovery exchanger does not depend on the ratio of the Reynolds numbers of exhaust gases and air. It is established that of initial and final moisture content ratio of exhaust gases, equal to 2.7, and the Reynolds numbers ratio of exhaust gases and air, equal to 0.8 and 1.2, depending on the values of initial and final moisture content ratio of exhaust gases, can be taken as the optimal values of the operating parameters. Key words: heat-recovery exchangers, exergy efficiency, complex techniques
V. Deshko, National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, I. Bilous, М. Osadcha
Energy and automation pp 26-38; https://doi.org/10.31548/energiya2021.02.026

Abstract:
The issue of energy efficiency of buildings is now relevant for Ukraine, as the vast majority of them belong to the mass construction of the twentieth century. Efficient use of thermal energy presupposes the expediency of taking into account, in addition to heat loss, also additional heat inputs, among which - solar heat inputs to the building area. In some methods, this component is not taken into account, or is taken into account quite large. A dynamic approach to the analysis of energy performance of buildings is given in the European standard EN ISO 13790, which was introduced in Ukraine in 2013, using the model 5R1C. But this method has not been widely used in Ukraine. The aim of the study was to increase the efficiency of energy management of buildings by taking into account solar heat in their area in different methods and models. The paper presents suggestions to amend the appliance of the heat load graph and math modeling for measuring energy consumption of the buildings. Amendments include forecasting that considers solar heat impact on the building. Work done based on the example of 5 floored apartment building. Authors of the paper made an analysis of the variability of climatic data using international hourly weather data for Kyiv. Comparative analysis of the three different methods of calculations of solar heat impact showed promising results: using heat load graph with consideration of solar heat impact allows to reduce the energy consumption allotted for heating by 37 % for North-South window orientation and by 28 % for West-East window orientation; using DSTU B A.2.2-12:2015 standard allows to achieve reduction by 11 % for North-South window orientation and by 9 % for West-East window orientation; using grid model 5R1C – 10 % for North-South window orientation, 8.5 % for West-East window orientation. Key words: heat energy consumption, heat load graph, dynamic model, solar heat impact
B. Kotov, STATE AGRARIAN AND ENGINEERING UNIVERSITY IN PODILIA, V. Hryshchenko, Yu. Pantsyr, I. Herasymchuk, The National University of Life and Environmental Sciences of Ukraine
Energy and automation pp 118-126; https://doi.org/10.31548/energiya2021.02.118

Abstract:
Currently, to create a microclimate in the production facilities of agro-industrial production are widely used utilizers of waste heat of ventilation emissions. But the air of such premises is clogged with dust impurities and has a high moisture content, as a result of which condensate falls on the heat-transfer surfaces, and dust sticks to the moistened surface. As a result, the efficiency of heat exchangers is significantly reduced, and the hydraulic resistance increases, which can cause a decrease in air supply. Therefore, there is a need to combat dust in the air supplied to heat recovery units. The most common method of purification of gas streams from solid dust impurities is the deposition of the latter in electrostatic precipitators, to increase the efficiency of which use gravitational moving water film. Currently, there are no mathematical descriptions and calculated dependences for horizontal electrostatic precipitators and electrohydrocyclones. The aim of the study is to formulate a mathematical description of the processes of movement of solid particles in the chambers of the horizontal electrostatic precipitator and electrohydrocyclone. The analysis of the existing systems of heat utilization of exhaust air and influence of dustiness on efficiency of their use is resulted. The possibility of using various systems for dust cleaning of exhaust air in agro-industrial facilities is considered. The technological and constructive scheme of the electrotechnological complex of utilization of heat of ventilating emissions which includes the electrohydrocyclone for clearing of dust of exhaust air is offered. The effect of determining forces, including electric, on the motion of a dust particle in the rotating flow of an electrohydrocyclone is analyzed. Equations describing the motion of a particle in an air rotating flow under the action of an electric field are determined, and mathematical models are compiled to calculate the trajectory of the dust particle. Simplified analytical expressions for particle motion trajectories are presented. Keywords: dust, separation, electric field, cyclone, airflow
Yu. Romasevych, National University of Life and Environmental Sciences of Ukraine, V. Loveikin, V. Krushelnitsky, V. Makarets
Energy and automation pp 69-80; https://doi.org/10.31548/energiya2021.02.069

Abstract:
In this work, experimental studies were conducted to evaluate the adequacy of the model of the „crane-load” system movement. For research, a laboratory installation (trolley with a load on a flexible suspension), a frequency converter, and encoders were used to measure the position of the trolley and the angle of deviation of the rope with the load from the vertical. Six experiments were performed by varying the duration of the increase and decrease of the frequency of the supply voltage of the trolley drive from 0.5 to 3 s. The increase and decrease of frequency voltage occurred according to a linear law. The data obtained during the experiments were compared with those that correspond to the mathematical model of the „crane-load” system. The mathematical model uses the Kloss equation, and also takes into account the change of frequency of the supply voltage of the drive from the condition of ensuring the overload capacity of the drive. Estimation of deviation of experimental data with results of numerical integration of mathematical model of the movement of the „crane-load” system was carried out based on the coefficient of variation (quantitative analysis) and graphic dependences (qualitative analysis). The obtained results showed the adequacy of the mathematical model of the motion of the „crane-load” system in the form of a system of nonlinear differential equations. Key words: mathematical model, dynamic system, frequency-controlled drive
V. Ramsh, Separated Subdivision of National University of Life and Environmental Sciences of Ukraine
Energy and automation pp 127-134; https://doi.org/10.31548/energiya2021.02.127

Abstract:
The question of research of dependence of efficiency on loading of the drilling machine is considered. To achieve this goal in the work were set and solved the following tasks: - to analyze the design and technological features of the drilling machine part; - to develop a new design of a drilling machine with a network analyzer; - to investigate the new design of a drilling machine with a network analyzer. About 80 % of drilling machines at Ukrainian enterprises are operated in excess of the established shelf life, which leads to their low quality of operation, high accident rate and failure of electromechanical equipment. The average shelf life of the electric drive in the industry does not exceed 6 years. Up to 10–18 % of electric motors and up to 30 % of auxiliary equipment fail and are repaired annually. The vast majority of engines can be repaired 4-5 times and after repair often do not work even for one year. The operation of drilling machines with an induction motor (short-circuited rotor), which are in poor technical condition, leads to an increase in financial costs due to increased power consumption. The cost of electricity consumed by the electric drive of drilling machines during the service life is significantly higher than the cost of equipment and maintenance costs and more than 4 times higher than its own. The electricity bill includes a system of surcharges for additional reactive power consumption. Reactive power charges at enterprises account for up to 10% of total electricity costs, and these costs tend to increase. Today, there is a need to apply the latest technical solutions and scientific approaches to solving the problem of improving the quality of operation of asynchronous electric drives of drilling machines. A research stand has been developed to determine the asynchronous motor of a drilling machine, which allows to identify the dependence of efficiency on the magnitude of the load, calculate the parameters of the substitution scheme and energy characteristics for the nominal mode of operation of the electric drive. Key words: drilling machine, network analyzer, research stand
A. V. Nesvidomin, The National University of Life and Environmental Sciences of Ukraine
Energy and automation pp 146-153; https://doi.org/10.31548/energiya2021.02.146

Abstract:
The article reveals an analytical description of the formation of families of orthogonal flat curved lines in the implicit form based on the analysis of the parametric equation of a flat isometric grid constructed by separating the real and imaginary parts of the function of a complex variable. This problem is due to the fact that flat isometric grids, as two families of orthogonal coordinate lines with square cells, are used in conformal mappings, for example, when drawing images on curved surfaces with the least distortion. At the same time, families of flat parallel lines are widely used in geometric modeling of heat transfer, electric fields, fluid flow, etc. There is a connection between these geometric images, which is explained by specific examples. Analytical calculations of deriving the parametric equation of an isometric grid are quite time-consuming, so they are performed in the environment of symbolic algebra Maple. For this purpose, the corresponding software of the interactive model of derivation of parametric equations of isometric grids for any initial function of a complex variable with the subsequent separation of its real and imaginary parts was created. It was found that the values of the abscissa and ordinates of the parametric equation of a flat isometric grid can be represented as explicit surface equations. For integer values of the power of the exponential function of the complex variable, the values of the abscissa and the ordinate will be represented by algebraic surfaces in the explicit form. The projections of the cross sections of the abscissa and ordinate surfaces by horizontal cutting planes on the horizontal plane form two families of curved lines, the equations of which can be obtained only implicitly. By the example of the quadratic function of a complex variable, it is proved that these families of lines are mutually perpendicular. The practical application of building a family of lines for geometric modeling of fluid flow lines that flow around the barrier in the form of a semicircle is shown. Key words: isometric grids, functions of a complex variable, families of orthogonal lines, geometric flow modeling
P. Klendiy, Separated Subdivision of National University of Life and Environmental Sciences of Ukraine BEREZHANY AGROTECHNICAL INSTITUTE, L. Kolodiychuk, O. Dudar, SEPARATED SUBDIVISION OF NATIONAL UNIVERSITY OF LIFE AND ENVIRONMENTAL SCIENCES OF UKRAINE BEREZHANY PROFESSIONAL COLLEGE
Energy and automation pp 81-96; https://doi.org/10.31548/energiya2021.02.081

Abstract:
Electric pumping units are not characterized by optimal operating modes and today are energy-intensive technologies. Water consumption is determined by unevenness and is formed under the influence of many, often uncontrollable factors. The inconsistency of the planned water supply regime with the actual water consumption leads to excessive pressures, which causes not only direct overconsumption of electricity at pumping stations, but also increases the likelihood of accidents in the network, contributes to greater water losses due to leaks in the water supply network. additional overconsumption of electricity consumed by pumping units to compensate for pressure loss. With the right choice of electric pump unit, its mechanical characteristics and power of the motor are designed to provide the required pressure in the system at maximum water consumption (morning and evening). At other times of the day, due to the decrease in water consumption, the pressure in the system increases and it is necessary to cover the throttle valve, and this requires constant rotation near it and is accompanied by electricity losses. In electric pumps, which are equipped with an unregulated electric drive, the flow control is carried out in almost the only traditional way - throttle on the discharge side. The paper reveals the need for transition from throttle control systems of pump units to automatic control systems by automatically maintaining the required technological parameter, in particular, the pressure at the flow rate of changing water due to the use of frequency-regulated asynchronous electric drives. Keywords: water pumping unit, energy consuming technologies, throttling, frequency-regulated electric drive
V. Savchenko, The National University of Life and Environmental Sciences of Ukraine, О. Sinyavsky, I. Bolbot
Energy and automation pp 17-25; https://doi.org/10.31548/energiya2021.02.017

Abstract:
Pre-sowing treatment of sunflower seeds in a magnetic field makes it possible to improve the sowing quality of seeds and increase the yield of sunflower without the use of mineral fertilizers and chemical plant protection products. Compared to other electrophysical methods, pre-sowing treatment of seeds in a magnetic field is a highly productive, energy-consuming, safe method for operating personnel and the environment. It has now been established that the yield and biometric indicators of agricultural crops depend on the dose of magnetic treatment. Therefore, the aim of the study was to determine the optimal energy dose for processing sunflower seeds in a magnetic field. An analytical expression has been obtained for determining the energy dose of sunflower seed treatment in a magnetic field. It contains all the operating parameters of seed treatment in a magnetic field. It has been established that the energy dose of sunflower seeds treatment in a magnetic field depends in direct proportion to the square of the magnetic induction and pole division and inversely to the speed of the seeds in the magnetic field. The carried out multifactorial experiment made it possible to determine the sunflower seeds germination energy and germination at various energy doses of treatment. This made it possible to determine the optimal mode of sunflower seeds treatment in a magnetic field. It was found that the optimal mode of pre-sowing treatment of sunflower seeds in a magnetic field is a magnetic induction of 0.065 T, four-fold re-magnetization, pole division 0.23 m, a seed velocity of 0.4 m/s, providing an energy treatment of 3.8 J‧s/kg. With the optimal treatment of sunflower seeds in a magnetic field, the germination energy increased by 28 %, the germination – by 24 %, and the yield – by 26 %. Key words: sunflower, pre-sowing treatment, magnetic field, magnetic induction, pole division, velocity of seed movement, energy dose of treatment
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