Centralized Heat Supply Research Articles

About expediency of changing the connection diagram of hot water supply units

PURPOSE. The article is devoted to an urgent problem for domestic district heating. A widespread situation is considered when consumers from heat supply systems with a closed connection scheme for hot water supply plants are switched to an open heat supply system from a thermal power plant. METHODS. Study of operating modes of operating heat supply systems was performed. Data collection was carried out using an online system for monitoring and commercial accounting of energy resources. Methodology for calculation of compared mode parameters is proposed. RESULTS. Using the example of the existing heat supply system, it is shown that the effect of the measure to switch subscribers of uneconomical boiler houses to heat sources with combined heat and power generation is leveled by legislative restrictions on the development of open heat supply systems, as well as by the regulatory method for determining heat consumption in hot water supply systems. The main technical and economic indicators were selected for comparative analysis of the operation of the centralized heat supply system in conditions of complete switching of hot water supply plants according to an open circuit and in the presence of a certain number of hot water supply plants with a closed connection scheme. CONCLUSION. The period of inefficient operation of the centralized heat supply system was determined and the amount of annual economic damage was calculated, which made it possible to prove the need to bring all schemes for connecting hot water supply plants in one heat supply system to a single type.

Flow and heat transfer characteristics and comprehensive evaluation of asymmetric plate heat exchangers for centralized heat supply

The structure of flow channel on both sides of the conventional plate heat exchanger(CPHE) is symmetrical. CPHEs are struggle to perform efficiently when subjected to asymmetric working conditions in district heating system. In order to improve the performance of plate heat exchangers under asymmetric conditions, asymmetric plate heat exchangers(APHEs) was designed. In this paper, APHEs were parameterized by asymmetric factor a. An evaluation index η for APHE is introduced to quantitatively analyze APHE’s suitability in district heating system. Numerical simulations were performed to investigate the heat transfer characteristics and resistance characteristics of the APHEs with 11 asymmetric factors a. Through using η, APHEs with the best comprehensive performance were found, when the flow ratio is 1.50, 1.75, 2.00, 2.25, 2.50 and 2.75. In flow ratio, APHEs provide the comprehensive performances with an improvements of 28 %, 39 %, 54 %, 65 %, 72 % and 83 % compared with CPHEs. Correlations equation for the average Nu and f on both hot and cold sides of the APHEs were established. There exists a correlation between Nu and f for the APHEs with respect to asymmetry factor a and flow ratio.

Dynamic model of integrated electricity and district heating for remote communities

District heating networks offer promising solutions for remote communities, providing centralized heat supply, improved efficiency, and diverse energy sources, especially with existing diesel generation. Hence, this paper bridges gaps in the existing literature by developing comprehensive dynamic models of combined district heating networks within existing electric power networks in remote communities, which allows identifying challenges and benefits of district heating networks for these communities. It is shown that district heating networks allow utilizing waste energy to enable energy exchanges between the electricity and heating systems, enabling the provision of necessary ancillary services for remote microgrids with renewable energy sources. The presented dynamic district heating network model incorporates particular considerations in remote, northern communities such as soil limitations, extreme cold conditions, and piping insulation to minimize heat loss. It also addresses accurate sizing of heat pumps based on realistic thermal load requirements, weather conditions, and consumer profiles, proposing demand management controls to enhance frequency regulation for the integration of variable renewable energy sources. The main contributions of the paper include detailed dynamic modeling for district heating network operation, heat pump demand response control system design, and a comparative analysis between centralized district heating networks and decentralized electric thermal storage units that have been deployed for thermal supply in remote areas. The presented dynamic models are applied, tested, and validated in an existing electric microgrid at Kasabonika Lake First Nation in Northern Ontario, showcasing the role of a potential district heating network in facilitating renewable energy sources integration in isolated microgrids.

Повышение энергетической эффективности работы тепловых сетей за счет утилизации тепловых потерь

The efficiency of thermal energy transfer, which is inevitably accompanied by heat losses through the insulation of pipelines, directly characterizes heating networks and centralized heat supply systems in general. The most important task in terms of current approaches to energy efficiency is to improve the efficiency of thermal energy transfer in modern heat supply systems. Currently known technical solutions to reduce heat losses through insulation of pipelines reduce heat losses, but not significantly. So, the purpose of this study is to develop a technical solution to reduce (even eliminate) standardized linear heat losses in heat supply networks of industrial enterprises. The authors have used methods of experimental research of heat transfer processes and mathematical modeling of heat and power equipment. A device for recycling heat losses is proposed. It is designed to reduce (even eliminate) normalized linear heat losses in heat supply networks of industrial enterprises. The permissible heat absorption of the device collector is determined, and a method for its regulation is described. An engineering method for calculation of the proposed device has been developed. The effectiveness of application of heat-reflecting screens in heating networks has been determined. A number of problems have been solved to improve the efficiency of heat supply systems of industrial enterprises using a device for recycling heat losses in the heating system channel.

Policy implications of challenges and opportunities for district heating – The case for a Nordic heating system

District heating (DH) is an efficient urban heating solution. Numerous external factors (energy efficiency, fuel-price increases, heat -pump competition and policy changes) are challenging. It is relevant to explore long-term cost-competitiveness of DH. A model has been developed testing three, future DH pathways: (i) phase out of biomass (aligned to the cascading principle of the EU Taxonomy), (ii) including waste heat in the fuel supply mix (aligned to the updated Energy Efficiency Directive) and (iii) lower system temperatures (aligned to the idea of more renewables and waste heat).The model considers the long-term development of the supply and demand sides together and simultaneously. This allows the model to determine the most cost-efficient heating solution for different building types in different points in time.The results confirm that a phaseout of biomass would erode -but that developments rendering lower system temperatures and increased waste heat utilization would strengthen-the DH business case. Additionally, it is confirmed that heat pumps constitute the main competition to DH. Hence, to remain a cost-efficient heating alternative in the future, DH systems need to revisit the tradition of centralized heat supply resorting to combustion for decentralized heat supply resorting to heat supply on demand.

System for monitoring building heat consumption

Relevance. Energy consumption and efficient use of district heating networks affect the environment, society and the economy. Solutions are needed that can significantly reduce specific thermal energy losses. Using a technically and economically feasible way to assess energy efficiency allows these decisions to be made. Currently, assessing the energy efficiency of buildings raises significant questions among specialists. There is not much modern specialized literature in this area. The problem of energy efficiency requires more rigorous attention to urban planning issues. Thus, refined methods for assessing the energy efficiency of buildings make it possible to simultaneously save capital investments and ensure efficient consumption of thermal energy. Aim. To develop a system for assessing the real heat consumption of buildings to ensure optimization of dispatching of centralized heat supply systems in real time. Methods. Computer modeling of the state of heat consumption of buildings with various characteristics and schemes for their connection to centralized heat supply networks; methods of geographic information analysis. Results. The authors have proposed the system for monitoring the heat consumption of buildings. This system allows assessing the energy efficiency of buildings through the maximum use of computer and software technologies. It is shown that the calculated heat flows of buildings used to predict savings when modernizing buildings do not always correspond to the actual heat loads, which can lead to an incorrect assessment of investment projects. The authors obtained graphical dependences of the quantities influencing specific heat losses on various primary independent factors. Conclusions. The constructed system for monitoring the heat consumption of buildings allows, together with the use of geoinformation analysis methods, obtaining a fairly complete picture of the state of heat consumption for city areas and an assessment of the energy characteristics of buildings.

THERMODYNAMIC IMPERATIVES THE MODERNIZATION OF THE ELECTRIC DRIVE OF PUMP UNITS OF THE CENTRALIZED HEAT SUPPLY NETWORK IN THE CONTEXT OF INCREASEING ENERGY EFFICIENCY

The relationship between thermodynamic and hydraulic parameters of the heat supply network has been established. The dependence of the electric power consumed by the electric drive of the pump unit on the pressure and supply of the coolant was determined. It is proved that the regulated electric drive system has advantages over the non-regulated electric drive system in the context of energy efficiency of the pumping unit and the district heating network in general. Approaches and criteria for the synthesis of a regulated electric drive system, including its automatic control system, were determined, regulation methods were analyzed, and the most acceptable version of the electric drive was chosen: a controlled frequency converter - an asynchronous motor with a short-circuited rotor, taking into account the above, an energy-saving mechanical system of a centralized heat supply network was synthesized. The peculiarity of this system is that the protection of parameters of hydraulic and temperature regimes in the network of centralized heat supply is ensured with the help of extreme automatic control systems. At the same time, the assignment of mode parameters is provided by the temperature controller of the heat exchange point of the network. Regulation of the pressure and productivity of the pumping unit is carried out by changing, according to a certain law, the frequency and power supply of the asynchronous motor.

ENERGY POTENTIAL OF DISTRIBUTED GENERATION AT POWERFUL BOILER HOUSES OF UKRAINE IN CONDITIONS OF MILITARY AGGRESSION

The Integrated Power System of Ukraine (IPS) is purposefully destroyed by the russian aggressor and suffers significant damage, which has caused long-term emergency interruptions in the power supply of critical infrastructure facilities, enterprises and the population. One of the ways to increase the stability of the IPS of Ukraine is to increase the share of distributed generation in its composition. The conceptual idea of solving this problem is the transformation of existing critical infrastructure objects from electricity consumers into electricity producers/suppliers who will provide their own electricity needs and the needs of other electricity consumers. Boiler houses of centralized heat supply systems (DHS) of Ukrainian cities with their existing electric power and fuel infrastructure can become such objects in wartime conditions. The author proposes the widespread introduction of energy-efficient cogeneration gas-piston units (CGPUs) at boiler houses of the DHS. The container-type CGPU is a typical mass-produced equipment that is manufactured in Ukraine and abroad and has a short implementation period (up to 5 days from the date of delivery to the industrial site of the boiler house). The high maneuverability of the CGPUs allows for an increase the flexibility of the IPS of Ukraine. The article presents the main technical and economic indicators of distributed generation with the use of CGPU at existing boiler houses for further national planning of the development of distributed generation during the martial law and post-war reconstruction of Ukraine. The application of CGPU at boiler houses of the DHS of Ukrainian cities has the potential to provide additional distributed generation with a total capacity of up to 2365.7 MW, in particular, 1224.8 MW at 158 boiler houses with a thermal capacity of 100 Gcal/h and more (612 CGPUs with an average unit electric power of 2.0 MW each); 561.9 MW at 409 boiler houses from 20 to 100 Gcal/h (803 CGPUs of 0.7 MW each); 561.9 MW in 2101 boiler houses from 3 to 20 Gcal/h (4136 CGPUs of 0.14 MW each). Under the conditions of 8 hours a day of use of the installed capacity of CGPUs, 567.8 thousand MWh of electricity will be produced every month at the boiler houses of the DHS (taking into account the consumption of the boiler houses for their own needs and release to the network to other consumers) and 136–142 million cubic meters of natural gas will be consumed. According to the average specific cost of modular CGPU (turnkey supply) from 800 to 950 USD/kW of installed electric capacity, capital costs for implementing the CGPUs with a total capacity of 2,365.7 MW will amount to USD 1.89–2.25 billion. Bibl. 31, Fig. 3.

PROBLEMS OF RELIABLE HEAT SUPPLY PROVIDING IN THE CONDITIONS OF NON-GUARANTEED ELECTRICITY SUPPLY TO HEAT-GENERATING ENTERPRISES

The paper analyzes the current state of centralized heat supply systems. Considered problems that arise when the power supply is turned off for a longer period of time. For example, due to natural disasters or the destruction of power stations, substations and networks. An analysis of the consequences of long-term shutdowns of centralized heat supply sources in the winter period at extremely low temperatures, which leads to the failure of the main and auxiliary equipment, heat networks and domestic heating systems, was carried out. Considered several real options for reservation or full self-sufficiency of boiler room heat supply needs in power supply for the most common types of boiler room. Namely, with water heating boilers and direct connection to the heating network and with steam boilers and steam water boilers. It is proposed to introduce elements of own power generation on a permanent basis, as part of the technological process of the heat supply system or a separate boiler house of medium and large capacity, which, with their rational combination, can lead to a significant economic effect. It is shown that the most promising is the redundancy due to the built-in heat generation scheme, the electricity generation system, i.e. full or partial cogeneration. It was found that when gas turbines are used in the cogeneration system of heat and electricity, it is advisable to use units with a low temperature of up to 800°C and a gas pressure before the turbine of up to 0.8 MPa, which are characterized by high reliability, low cost and provide the greatest release of utilized heat. Keywords: centralized heat supply systems, reliability of power equipment, power supply of boiler houses

Анализ сценариев организации теплоснабжения горных территорий на основе комплексных решений по их устойчивому развитию

Introduction. In the modern world, planning for the sustainable development of countries at the state level should take into account the economic-geographical position (abbr. – EGP) of the territories, which determines the nature of the organization of their heat supply, which is of particular relevance for mountainous areas. Materials and methods. The starting point of the study was an analysis of the structure of the sustainable development goals (abbr. SDGs), among which five SDGs were selected, interconnected with each other and with the EGP (SDGs 7, 3, 9, 11, 13). To compile the materials, statistics on the countries of the post-Soviet space of the World Energy portal were used. Two main types of energy economy of countries were identified, meeting the needs for heat supply, which are largely determined by the EPG of the territories. Results. It is shown that the organization of heat supply to territories needs to be improved in the context of SDG 7 “Affordable and clean energy”, so the question arises about strategic planning of its scenarios. Based on the results of the study, five scenarios were proposed for selection aimed at the sustainable development of territories: centralized heat supply, the use of traditional decentralized sources, the transition to the use of electricity, the development of renewable energy sources and the transition to nuclear energy. Discussion. In the mountainous areas of the countries studied, the use of one of the proposed scenarios is not possible; a combined scenario for organizing heat supply is required. The authors propose to use an approach based on the method of hierarchy analysis, on the basis of which provisions are formulated for its application in order to plan the sustainable development of mountain areas. Conclusion. Based on the results of the work, conclusions were drawn that reflect the stages of the research, which are based on a scientific and practical approach to the formation and selection of scenarios for organizing heat supply to mountainous areas. Areas of promising practice-oriented research include studying the possibilities of using renewable energy sources (including solar and wind power plants), which are currently little used in heat supply to mountainous areas.

A comprehensive planning study on the thermal potential of various biomass conversion technologies: Case study of 47 cities in China

Biomass energy, as a new type of clean energy, accounts for less than 3% of the energy use structure, far lower than that of traditional fossil fuels. Therefore, the use of different biomass conversion technologies in areas with rich biomass resources can provide electric energy, heat energy, natural gas, biomass liquid fuel, and other energy to a large extent; in insufficient biomass resources, appropriate biomass conversion methods should be selected to effectively improve the energy utilization efficiency, or continue the use of traditional energy to a certain extent to meet the energy needs of different cities. Consequently, appropriate biomass conversion modes should be selected to improve energy utilization efficiency and to meet the energy demands of different cities. This study calculates the biomass potential heating value, bioenergy demanded heating value, biomass technology potential, and bioenergy supply and demand surplus relationship coefficients of 47 prefecture-level cities in three provinces of China. The calorific value, as the combustion value index to measure biomass and traditional energy, gives the spatial planning scheme for the biomass conversion technology of 47 prefecture-level cities from the perspective of energy conservation. The results of the analysis show that 11 winter cities in Heilongjiang Province are suitable for the development of biomass solid direct combustion conversion technology and biomass liquid fuel conversion technology, enabling the energy supply and demand surplus coefficients of two such biomass conversion technologies to be greater than or equal to 6.37. The exception is Da Hinggan Ling Prefecture. The results further reveal that 15 prefecture-level cities with central heating supply in Henan Province are suitable for the development of biomass solid direct combustion power generation technology and biomass liquid conversion technology, enabling the energy supply and demand surplus coefficients of two such biomass conversion technologies to be greater than or equal to 0.75. In this province, the exception is Zhengzhou. Lastly, the results also indicate that 15 prefecture-level cities without central heating supply in Anhui Province are suitable for the development of biomass liquid fuel conversion technology, enabling the energy supply and demand surplus coefficient of such technology to be greater than or equal to 22.92.

Особливості забезпечення якості та тарифного регулювання послуг теплопостачання

The article deals with studying the state of providing heat supply services. The quality indica-tors of centralized heat supply services have been categorized. The evaluation of the quality of cen-tralized heat supply services hinges on principal benchmarks such as punctuality in starting and fin-ishing the heating season, uninterrupted service provision, and adherence to current regulations. Having analysed the heat energy supply, its pricing was divided into two components – condi-tionally permanent and conditionally variable. Such division allows us to mitigate the adverse effects of the seasonality of this housing and communal services category. It's noteworthy that this tariff formation developed with the 'cost plus' method (which also includes heat energy losses), is assumed imperfect according to European standards. It provides only a minimal level of profitability, which neither fosters equipment development nor encourages cost savings nor motivates employees. The study on the quality of heat supply services revealed that the assessment was primarily based on the minimum technical requirements and consumer relations. The article states that the principal challenge in providing high-quality heat supply services is the lack of competition in this sector. Heat supply enterprises do not have enough incentives to enhance their efficiency and seek opportunities for implementing investment programmes to ensure a more cost-effective service sup-ply. To improve quality and resolve current issues the authors propose to adopt non-conventional measures, to investigate changes in the quality of heat supply services and how they are evaluated by consumers, to inform the regulatory housing and communal services authorities and local self-government bodies about the existing problems of heat supply services and their quality so that they can make effective management decisions. For the purpose of enhancing the quality of heat supply services, it has been recommended to use monitoring based on the integrated quality index calculation. This index comprises elements such as commercial service quality, service reliability, service accessibility, and technical quality.

On the Feasibility of Building Mini-Thermal Power Plant Using Local Fuels in the Conditions of the Republic of Belarus. Part 2. Role of Mini-Thermal Power Plant in Heat Supply Systems of Cities and Settlements in Belarus

. Within the framework of ensuring the country's energy security and pursuing a policy of decarbonization of the economy in the Republic of Belarus, it is assumed to maximize the use of its own fuel and energy resources (TER). However, the question of choosing the type of heat source in centralized heat supply systems when using local fuels (LF) remains open. The commissioning of the Belarusian Nuclear Power Plant and the relatively high unit cost of power generation capacities running on LF inclines the scales to use boiler houses as heat sources. Based on the world experience in the development and application of heating as the most energy-efficient solution in the field of heat supply, this problem has been studied in the conditions of Belarus. It is shown that the electric capacity of mini-thermal power plants using traditional LF connected to the unified system of the country is less than 100 MW, and the main technologies implemented at mini-thermal power plants using LF in the Republic of Belarus are traditional steam power plants with water steam as the working fluid (11 power plants) and steam power plant with organic Rankine cycle (ORC) (3 power plants). Geographically, mini- thermal power plants operating on LF are located evenly throughout the entire territory of the Republic of Belarus. The number of hours of use of the installed capacity of renewable energy sources (RES) of the Republic of Belarus has been determined. Energy sources based on organic waste and biomass (over 4,000 hours per year) and on hydro resources (about 3,500 hours per year) have a clear advantage, for which indicator of the number of hours of installed capacity use is much higher than for solar and wind power installations. In addition, biomass generating capacities have the lowest coefficient of electricity supply to the combined energy system. Based on the analysis of modern trends in the development of energy, technical and economic “attractiveness factors” for the construction of heating systems for heat supply on LF in the conditions of Belarus have been formulated, which, in addition to traditional factors (substitution of imported fuel – natural gas and oil), include improvement of the quality and reliability of energy supply to consumers in remote locations, development of polygeneration, reduction of losses of electric energy for its transport, participation in covering the electric load schedule of the unified power system, and also indicated the possibility of creating an energy hub on the basis of a mini-thermal power plant, structured for the integration of energy sub-sectors, distributed generation sources and the option of generating “green” energy carriers.

MODERNIZATION OF THE ELECTRIC DRIVE OF PUMPING UNITS OF THE DISTRICT HEATING NETWORK IN THE CONTEXT OF INCREASING THEIR ENERGY EFFICIENCY

Quantitative and qualitative indicators of the modernization of the electric drive of a pumping unit of a network with throttle control of the coolant supply of a centralized heat supply system are determined. The possibility of modernizing the electric drive by replacing outdated electric motors of energy efficiency class IE1, which are still used in electric drives of pumping units, with electric motors of energy efficiency classes IE2 and IE3 from different manufacturers, has been substantiated. The energy consumption was calculated based on the technical data of the pump and electric motors provided by the manufacturers and includes the calculation of the energy consumption of pumping units in a typical operating cycle typical for district heating networks, which involves operation at reduced load for a long time. Comparative calculated data on the daily and annual energy consumption of the considered electric motors in a typical operating cycle of a pumping unit, with respect to the least energy-efficient electric motor among those considered, were obtained. The practical significance of the results obtained is to understand that the selection of an electric motor by efficiency at variable load, i.e., actually on the basis of the IE energy efficiency class assigned in accordance with the IEC 60034-30-1 standard, is incorrect, It is substantiated that the choice should be made using the efficiency interpolated by the method of polynomial interpolation of the motor loss curve, while taking into account the economic feasibility of choosing an electric motor between energy efficiency classes, in this case IE2 and IE3, and different manufacturers.

Increasing the Efficiency and Security of Integrated Power System Operation Through Heat Supply Electrification in Ukraine

Introduction. The paradigm of global energy development is the priority of renewable energy sources (RES), namely, wind (WPP) and solar (SPP) power plants. This process has been evolving despite the fact that these renewable energy sources, by their physical nature, are unable to provide either a stable frequency of generated energy or a guaranteed power.Problem Statement. The current threatening situation in the Integrated Power System (IPS) and in the energy market of Ukraine is caused by the hypertrophied development of SPP and WPP in the structure of Ukraine’s IPS and excessive preferences given to RES by the “green” laws.Purpose. The purpose of this research is to create a fundamentally new structure and basis of the electric-heat system operation, which unite the IPS of Ukraine and the system of centralized heat supply (CHS), by electrifying the CHS through the use of autonomous RES energy and the capacities of nuclear power plants (NPP), in order to ensure the profitability ofUkraine’s energy market and the guaranteed profitability of RES.Material and Methods. Information of NEC Ukrenergo for 2021 and periodic energy publications; system analysis for established electrical, hydraulic, and temperature modes of joint operation of IPS, CHS, WPP, and SPP for a fundamentally new organization of their interaction.Results. Management based on the “green” tariff laws has led to a significant unprofitability of the Ukraine’s energy market. The greenhouse gas emissions during the use of RES in the IPS have increased several times, as compared with such emissions, in the case of the structure of the IPS without RES. The new principle of interrelationships between IPS, CHS, WPP, and SPP ensures high manufacturability, cost-effectiveness, reliability, and environmental friendliness of each component.Conclusions. The combination of IPS and CHS structures solves several problems of the national importance: the problem of frequency and power stabilization in the IPS automatically solves; the energy market of Ukraine gets rid of USD 15 billion loss anually; it allows saving 7.28 billion m3 natural gas and reducing the carbon dioxide emissions by 98 million tons in CO2 equivalent.

On the Feasibility of Building Mini-Thermal Power Plant Using Local Fuels in the Conditions of the Republic of Belarus. Part 1. State of Use of Local Fuels in Heat Supply Systems

As part of ensuring the country's energy security and pursuing a policy of decarbonization of the economy in the Republic of Belarus, the maximum use of its own fuel and energy resources (FER) is expected. However, the question of choosing the type of heat source in centralized heat supply systems when using local fuels (LF) remains open. The commissioning of the Belarusian Nuclear Power Plant and the relatively high specific cost of electricity generating capacities using local fuels tip the scales to the use of boiler houses as heat sources. However, world experience in the development and application of heating, as the most energy-efficient solution in the field of heat supply, requires a more thorough study of this problem. The paper presents an overview of the use of local fuels in Belarus and a number of European countries with developed centralized heat supply. Based on the analysis of open source data, the paper provides information on the state of use of local fuels in district heating systems of the Republic of Belarus and a number of European countries that have experience in the widespread use of solid biomass and where it constitutes a significant share in the structure of thermal and electrical energy production in relation to other fuel and energy resources. The main aspects of the energy programs of a number of European countries with the largest share of thermal and electrical energy generation using local fuels are presented. It has been revealed that the energy program of Finland is of the greatest interest for Belarus, where the share of nuclear energy in the structure of electrical energy production, just like in the Republic of Belarus, is approaching to 40 % and the energy strategy assumes an increase in the share of thermal power plants using local fuels in the structure of heat and electricity generation.

The impact of the heat supply industry on the level of energy efficiency of industrial territories and regions of Russia

One of the most important areas for improving Russian economy under the influence of sanctions pressure is to increase the level of energy efficiency in the consumption of fuel and energy resources. The aim of the study is to study the place and role of the Russian economy in the process of forming the world fuel and energy balance. An analysis of the data on the production and consumption of fuel and energy resources by Russia emphasized that the country occupies a leading position in terms of reserves, production volumes, consumption and exports of global fuel and energy resources, while the efficiency of energy consumption in the country is significantly behind the world average, which negatively affects the internal economic processes taking place in the country and requires the search for solutions to increase the level of energy efficiency. Research analyzes analyzes the volume of thermal energy consumption in Russia in comparison with the global scale, as a result it was revealed that the annual volume of thermal energy consumption in Russia is 11 times more than, for example, in Germany, 12.5 times more than in the USA, 12.7 times more than in Kazakhstan, which underlines the significant contribution of the heat supply industry to the lag in the level of energy efficiency of the Russian economy from the indicators of most countries. Analysis of the statistical data of average temperatures in various countries of the world, as well as the federal districts of the country, revealed the influence of the climatic factor on the volume of thermal energy consumption in Russia, which determines the impossibility of excluding the consumption of thermal energy to maintain the functioning of the Russian economy. The main result of the study is the revealed high role of the Russian economy in shaping the global fuel and energy balance, as well as the need to increase the level of energy efficiency of fuel and energy consumption. The materials suggest the improvement of alternative replacement models for consumed primary and secondary fuel and energy resources. As an energy replacement resource, it is proposed to use electric energy in the system of combined district heating of industrial areas. The use of electric boilers makes it possible to increase the energy efficiency of integrated energy supply, enhance the environmental friendliness of heat supply, and reduce the cost of the economy for centralized heat supply of individual territories.

USE OF SECONDARY ENERGY RESOURCES TO PROVIDE HOT WATER SUPPLY TO BUILDINGS AND CONSTRUCTIONS

The paper assesses the possibility of using secondary energy resources to provide hot water supply to buildings and constructions. The introduction of recovery systems by using previously unused cheap waste heat energy helps to reduce the amount of energy produced and consumed, increase energy efficiency, and reduce greenhouse gas emissions, which correspond to the development strategy of the construction industry and housing and communal services in the field of environmental protection and energy saving. A method for using the waste heat energy of refrigeration plants to provide hot water supply to an apartment building is proposed. This method makes it possible to ensure uninterrupted supply of hot water to consumers with minimal dependence on the operation of centralized heat supply systems. The minimum power of waste thermal energy sources necessary for the organization of such systems is calculated, and possible sources of secondary energy resources are proposed.

FREQUENCY REGULATION OF THE ELECTRIC DRIVE OF PUMP UNITS OF THE CENTRALIZED HEAT SUPPLY NETWORK BASED ON ASYNCHRONOUS MOTORS WITH A SHORT-CIRCUITED ROTOR

The quantitative and qualitative parameters of the frequency regulation of the electric drive of the pumping units of the centralized heat supply network were determined. The necessity and possibility of using the frequency-regulated electric drive of pumping units in the networks of centralized heat supply, in the mode of their operation of quantitative and qualitative regulation of the coolant supply, is well-founded. The frequency control parameters were calculated on the basis of technical data related to the operating mode, where the flow rate of the coolant changes according to the hydraulic load typical for HVAC applications defined by the European Union Regulation, as well as the technical data of the pump, frequency converter and electric motors provided by the manufacturers. The definition of parameters concerns the operation of pumping units in a typical operating cycle characteristic of district heating networks, which involves operation with a reduced load for a long time. The results were obtained that correspond to the range of the speed of rotation of the electric drive, its power, torque, coolant supply and hydraulic pressure of the pump in a real typical network of centralized heat supply. The practical significance of the obtained results is that they can be used for the modernization of the electric drive of pumping units of the centralized heat supply network, which until now are operated with non-regulated electric drives based on an asynchronous motor with a short-circuited rotor and throttle regulation of the coolant supply.

АКУМУЛЯТОРИ ТЕПЛОВОЇ ЕНЕРГІЇ

The article provides an analytical review of thermal energy storage. The reasons determining their demand are shown. It has been established that the market of thermal accumulators is developing quite dynamically. According to the forecast of the International Renewable Energy Agency, the global market for thermal accumulators may triple by 2030 from 234 GWh of installed capacity in 2019 to about 800 GWh in 2030. Investments in the development of thermal accumulators are expected to reach 13–28 billion US dollars. Their capacity for power generation can be 491–631 GWh, for heat supply – 143–199 GWh, for cooling – 23–26 GWh. Bloomberg NEF considers the main drivers of such a sharp increase in energy storage capacity are the US Inflation Reduction Act, which provides for more than $369 billion in financing for clean technologies, as well as the European Union's RE Power EU plan to reduce dependence on gas from Russia. The significant additional storage capacity expected from 2025 in the utility sector is in line with the very ambitious renewable energy targets set out in the REPowerEU plan. The purpose of this review is the search and analysis of thermal energy storage technologies for their possible use in the centralized heat supply of Ukraine. The conducted review showed that the most advanced technology for the accumulation of thermal energy is heat capacity of the material storage. It is the cheapest and most common in centralized heat supply. For short-term storage of heat energy, it is advisable to use storage tanks and main heat networks. Special insulated concrete underground storages of both natural and artificial origin are used for seasonal accumulation of thermal energy. A promising technology for seasonal thermal energy storage is an ice battery developed by the Viessmann company, which requires much less space than the heat capacity of the material storage technology. Thermochemical batteries are in the early stages of development, their demonstration samples may be manufactured by 2050. Keywords: battery, thermal energy, heat capacity, phase transition.