Polityka Energetyczna - Energy Policy Journal

The relevance of the subject of research is determined by the need to develop and subsequently implement a mathematical model and the corresponding structural scheme of the convective heating surfaces of the TP-92 steam boiler. The purpose of this research work is to directly model the heat- -transfer system of the convective heating surfaces of this boiler, designed for effective use in real conditions. The basis of the methodological approach in the research work is a combination of methods of the system analysis of the key principles of constructing mathematical models of heat-transfer systems of modern steam boilers with an experimental study of the prospects for creating a mathematical model of a heat-transfer system of the convective heating surfaces of a TP-92 steam boiler. In the course of the study, the results were obtained and presented in the form of a mathematical model of a convective heat-transfer system. It allows for making effective mathematical calculations of the main operating modes of the TP-92 steam boiler and calculating the dependences of the temperature and thermal modes of its operation on the change of incoming parameters of the used heat carriers, changes in the heating surface area and the relative flow rate of the heat carriers over the time of their use. The results obtained in the study, including the conclusions formulated on their basis, are of significant practical importance for the designers of steam boilers. The results also are useful for maintenance personnel, whose immediate responsibilities include determining the real possibilities of improving the convective heat-transfer system, based on the known parameters of the temperature of the coolant at the entrance to the system and at the exit from it.

The economical combustion of gas fuel implies that it takes place with a minimum coefficient of excess air and minimal losses. Constructive, aerodynamic and physical factors have a determining influence on the completeness of combustion and the conditions of ignition. Using the ANSYS software program, the main characteristics of the combustion process in the cylindrical mixing section of a flat flame injection burner are investigated through computer simulation. A geometric model was created on which it is possible to study both straight and rotating jets. The possibility of numerically investigating the combustion of gaseous fuel (C ₃H ₈) in a confined air flow produced by injection is considered. A k-ε model of turbulence was used, which is based on the equation for turbulent kinetic energy and its dissipation rate. The purpose of the work is to study and analyze the changes and distribution of temperature and speed as well as the concentration of nitrogen oxides and carbon monoxide along the axis of the combustion chamber. The results are presented for the angles of inclination of the nozzles of 45° and 0°. Based on these, an analysis was made, where it was found that with the increase in the degree of rotation, the absolute values of the temperature increase and the change in the mass concentration of the fuel along the length of the mixing section can be used to regulate the combustion process. The created numerical model can be successfully used to determine the main parameters of the burner under the same initial conditions, changing the angle of inclination of the nozzles. The obtained results can be considered as a basis for further research related to increasing the efficiency of the combustion process and lowering the harmful emissions produced by it.

The relevance of this research work is due to the fact that farms and other farms are located at a considerable distance from sources of centralized power supply. Therefore, it is necessary to introduce autonomous generators as the main units that ensure the uninterrupted functioning of energy systems. The purpose of this research work is to analyze the features of the functioning of an autonomous constant voltage generator, as well as to determine the basic physical laws that are of fundamental importance in its operation. The basis of the methodological approach in this scientific study is a combination of methods of system analysis with an analytical study of the general principles of operation of such devices, which are of fundamental importance from the point of view of ensuring the proper level of operational reliability. The main results obtained in this research work should be considered the definition of equations for calculating the instantaneous values of the three-phase excitation current, as well as the peak value of the three-phase excitation current of an autonomous constant voltage generator. The results obtained in the course of this scientific research and the conclusions formulated on their basis are of fundamental importance for developers of modern technological systems, including autonomous constant voltage generators, as well as for employees of technological services of modern industrial enterprises, whose professional responsibility includes the practical operation of such devices to solve a complex of technical tasks facing these enterprises.

The purpose of this research work is to study the issues of the protection of 6–10 kV lines and access ways overvoltage in the electrical networks of modern enterprises of high-energy intensity, as well as the search for real technical opportunities to improve the protection of power lines directly in conditions of their operation. The methodology of this scientific research is based on a combination of methods of system analysis of the principles of the functioning of electric networks of energy-intensive enterprises with an analytical study of the fundamental aspects of ensuring the protection of 6 to 10 kV lines and access ways from overvoltage. The results of the conducted scientific research indicate the relevance of the issues of ensuring the protection of lines and electrical networks of energy-intensive enterprises from overvoltage and the need to develop special technical devices to ensure the proper level of such protection in real conditions. The results and conclusions of this research work are of significant importance for developers and designers of electric networks of enterprises with increased energy capacity, as well as for employees of various power supply systems who, by their occupation, face the tasks of servicing electric networks, which include lines and access ways with specified operating voltage parameters and ensuring the proper level of safety and practical use of these electric networks of energy-intensive enterprises.

Solar photovoltaic (PV) and concentrated solar power (CSP) systems are the present worldwide trends in utilizing solar energy for electricity generation. Solar energy produced from photovoltaic cells (PV) is considered the main common technology used due to its low capital cost; however, the relatively low efficiency of PV cells has spotlighted development and research on thermal engine applications using concentrated solar power. The efficiency of concentrated solar power is greater than that of PV and considering the solar potential for Sudan. Therefore, this study has been performed in an attempt to draw attention to the utilization of CSP in Sudan since the share of CSP is insignificant in comparison with PV, besides the suitability of CSP applications to Sudan’s hot climate and the high solar energy resource, the study presents a design model of 1 MW parabolic trough collectors (PTC) using the Rankine cycle with thermal energy storage (TES) in Sudan, by adopting reference values of the Gurgaon PTC power plant in India. The design of a 1 MW Concentrated Solar thermal power plant using parabolic trough collectors (PTC) and thermal energy storage is proposed. The simulation was performed for a site receiving an annual direct normal irradiance (DNI) of 1915 kWh/m2, near Khartoum. The results showed that the plant can produce between nearly 0.6 to 1 MWh during the year, and around 0.9 MWh when it encompasses thermal energy storage with an average thermal efficiency of 24%. These results of the PTC Power plant encourage further investigation and the development of CSP technologies for electricity generation in Sudan.

The potential of wind energy in Ukraine is examined in this article. Possibilities of its use are analyzed, an analytical assessment of the potential for its use is performed, and prospects for the use of energy resources for the development of the wind energy market is substantiated. Reasons are provided for the advantages and disadvantages of wind energy, which should be combined into the following components.
The natural resource potential of Ukraine for the development of wind energy is analyzed. It has been confirmed that the wind energy potential of different territories of Ukraine is characterized by average annual wind speeds at the level of 7.0–8.5 m/s (on the continent – at heights of about 100 m, in water areas – about 50 m), which allows using megawatt-class wind turbines with annual coefficients of capacity utilization at the level of 0.3–0.4, which is quite efficient. The specific energy potential of wind energy in Ukraine is established, according to which, the territories of the country were grouped. It has been specified that the best places for locating wind power plants are areas with strong and constant winds, which can be found on the coast of the seas and in mountainous areas.
The situation with the production of energy resources in Ukraine is analyzed based on wind sources and means before the war. The advantages of wind energy development based on the improvement of legislative framework and promoting production of equipment for the operation of wind power plants in Ukraine are proven. The reasons for the potential of the wind energy market are stated and the main consumers of wind energy in Ukraine are outlined. The development of wind energy is considered as a method for energy independence of the national economy of Ukraine.

The generalization of the European experience in waste management in the context of the directives, decisions and regulations adopted in the last decade in the European Union, as well as the state of the organizational, economic and regulatory framework for solving the waste problem in Ukraine, reveals a systemic lag in the implementation of new conceptual, methodological and practical approaches to the formation of an appropriate state policy.
The dynamics of handling certain types of waste in Ukraine have been analyzed. Features of disposal and waste management in Ukraine have been identified. A comparative assessment of the dynamics of waste generation in European countries and Ukraine per capita has been carried out, a block model of the financing system for the waste management sector in Ukraine has been formed and the directions of effective waste management in Ukraine have been determined. Furthermore, priority policy measures for waste management and secondary resource use in Ukraine have been formulated.
A set of obstacles on the method of efficient waste management in Ukraine has been prioritized. In the context of the formation of an efficient waste-management strategy, it has been advised to structure its three components of the subsystem: receipts (sources of formation) of funds, their accumulation and costs (expenses). This structuring indicates the presence of a number of flows of funds, each of which is largely autonomous but together they create a complementary system. Improvements to the legislative framework have been suggested. In particular, it is recommended to devote more resources to reorienting the existing economic model, which will create new business projects and will increase the flow of investment into the country.

The introduction of increasingly strict rules related to the processing and storage of animal waste, the growing demand for energy and the creation of sustainable animal husbandry have led to an increased interest in the production of clean energy from animal waste. The production of biogas and its subsequent burning on the farm is among the most promising technologies. One of the possibilities for the utilization of biogas is through the use of small aggregates for the combined production of electricity and heat energy based on an internal combustion engine. Analysis of such facilities that have been put into operation show that alternative technologies using biogas as fuel are better than conventional options, both from an economic and an environmental point of view. In this sense, however, the introduction of such a technology into operation is always associated with a number of risks, since investments in new technologies are influenced by technical and economic uncertainty. When planning and preparing the plan for the construction of such a biogas facility, the investment costs, technical support and profitability of the project are essential. Introducing critical economic and technical parameters to inform the farmer of all possible investments, operational and unforeseen risks will allow him to accept the challenges and choose the best solution for his farm. In this publication, an analysis and assessment of the risk has been carried out based on the characteristics of the technology – the possible consequences of the risk are also presented. A risk matrix related to the specifics of the object and the technology is proposed, with the help of which, the type of risk is identified. Based on an analysis of the obtained results, a motivated proposal for reducing the risk is made.

This article presents some results of work on the selection of the most promising types of lamps for various objects in industry, in commercial and residential buildings. It is shown that the use of a particular type of lamp depends on the conditions of a particular country (the cost of credit resources, the availability of different types of lamps on the market, and government incentives or restrictions), as well as on the conditions of the specific object (cost of lamps, duration of operation during the day, tariffs for energy resources, the cost of equipment and its installation (dismantling, utilization), the cost of replacing the equipment after leaving it, the term of service of various types of lamps). It is also necessary to consider the possible risks of changes in tariffs and the cost of money.