Heat Supply Systems Research Articles

Analysis of Thermal Characteristics of a Solar Heat Supply System With Thermosiphon Circulation

In this paper, the characteristics of the vertical distribution of the thermosiphon in the conditions of the southern region of Kazakhstan are experimentally studied. The design was equipped with several thermocouples for measuring and collecting the provided data using a data logger. The collector temperature has reached 75 °C, and the time to reach the highest temperature is approximately 1.5 hours after the point of limiting the flow of solar radiation. During the sunny period, the temperature of the upper layer of water in the storage tank was 60 °C. This system was demonstrated during the winter days. The measured thermal characteristics of the alignment are in good agreement. At the maximum values of the temperature systems, the average daily efficiency of the system was 52% with the difference between the collector temperature and the ambient temperature. While on other days, the average daily performance of the system is about 50%. The initial temperature in the tank has an impressive effect on the daily return of the system. An increase in the temperature difference between the water temperature and the collector temperature will lead to an increase in the thermal power of the collectors. Compared to other days, the daily efficiency of the system can reach 60% at an initial temperature of 7°.

Improving the reactor for thickening organic plant-based polycomponent semi-finished products with high degree of readiness

The object of this study is the process of thickening organic polycomponent compositions based on Jerusalem artichoke, apples, pumpkin, cranberry, and dogwood to produce high-level semi-finished products employing the proposed equipment and technological solutions implemented in a unified reactor. Conventional thickening devices have a steam heat supply system, which leads to overheating of certain layers of raw materials and prevents the mobile properties of the apparatus under the conditions of significant execution of organic properties of raw materials. The introduction of apratur-technological solutions could provide the competitive advantage of the reactors by heating the film-like emitting electric heater using a mixing device with a heating surface. Increasing the total area of heat exchange to 1.24 m2 (prototype – 0.98 m2). There is a decrease in specific heat consumption by 20 %, specific metal capacity by 47 %, and the duration of the process by 30 %. We have determined rheological properties in the thickening of the organic polycomponent composition of the paste at a temperature of 55 °C and a shift rate within 3.0…4.5 s-1, effective viscosity is in the range of 22...3.5 Pa·s. In this case, the kinetics of boiling in an improved reactor are by 27 % smaller than that in the basic structure R-P-150m. According to organoleptic indicators, the composition "B" has a pleasant harmonious taste of all components. The results of the studies are relevant for practical implementation in the temperature range from 35 °C to 55 °C. The hardware and technological solutions form the competitiveness of mobile reactors for the thickening of plant semi-finished products under conditions of elimination of the steam component and an increase in the surface of the heat exchange of the mixing device. Providing preference in operating duration with the simultaneous use of Peltier elements to convert secondary heat to the autonomous work of exhaust fans in the motor compartment

PERFORMANCE OF HEAT PUMP BASED ON COMPOSITE ADSORBENT ‘SILICA GEL – CRYSTALLINE HYDRATE’

Performance of an adsorptive heat pump has been studied. The factors affecting the efficiency of its work have been analyzed. Operating parameters and efficiency of adsorptive heat pumps and adsorptive heat storage devices have been compared. An algorithm of calculating the basic operating characteristics of an adsorption heat pump in heat supply systems has been proposed. It involves calculating the mass transfer coefficient, final absolute humidity of the air flow passed though adsorbent layer, the water uptake or adsorption and the useful heat of adsorption and heat of condensation, determination of heat inputs for the operation of the device such as heating the adsorbent, case of the device, hydraulic circuit, the water in the tank and adsorbed water, heat of desorption and heat of evaporation, estimation the coefficient of energy performance. The evaluation criteria of the efficiency of adsorptive heat pumps and heat storage devices have been compared. It is shown that the operating parameters of the adsorptive heat pump and the adsorptive thermal energy storage device based on composite adsorbents ‘silica gel – sodium sulfate’ and ‘silica gel – sodium acetate’ are the same, i.e. airflow rate 0.08 - 0.1 m3/s and initial absolute humidity of airflow 0.03 – 0.04 kg/m3, which are corresponded with maximal efficiency of the device. The temperature of the humid air flow directed to the adsorbent layer is suggested to be set at 20 – 40 °C. The measures to increase the efficiency of the adsorptive heat pump are proposed. It is shown that ultrasonic air humidification allows to increase the coefficient of energy performance by almost 2 times compared to steam humidification. The obtained results can be used for developing energy-efficient heating systems of residential premises.

Study on the operational feasibility domain of combined heat and power generation system based on compressed carbon dioxide energy storage

Compressed carbon dioxide energy storage (CCES), as one of the compressed gas energy storage (CGES) technologies, can make the system capable of combined heat and power supply by storing and releasing electrical energy in the form of heat and potential energy, which is of positive significance for realizing efficient and comprehensive energy utilization and promoting the development of energy storage technology. A combined heat and power supply system based on compressed carbon dioxide energy storage (CCES-CHP) and its mathematical model are constructed. In order to construct a visualized operational feasibility domain, the dimensionless factors γ1 and γ2 and the ratio parameters α1 and α2 are defined to reflect the coupling relationship between the system storage/release energy power, mass flow rate and cooling/heat release power. A dual state of charge (SOC) model of heat and gas storage is also constructed. Further research is conducted on the shape and characteristics of the operational feasibility domain under the combined heat and power mode. The change of the ratio of themoelectric distribution ratio dispatch and wide operating conditions are analyzed. Thus provide an idea for evaluating the flexibility of the system operation combined heat and power capacity and response tracking. Finally, the analysis process and application potential of the proposed operational feasibility domain analysis method were validated for a typical integrated energy system.

ДИСТАНЦИОННОЕ ОБНАРУЖЕНИЕ УТЕЧЕК В ТЕПЛОЭНЕРГЕТИЧЕСКИХ ТРУБОПРОВОДНЫХ СИСТЕМАХ

The features of the development of technical diagnostic methods for remote control of the parameters of the operation of thermal power pipeline systems are considered, with a main focus on heat supply systems, including leak detection, as well as in the creation of software for automated control systems. Mathematical models for remote leak detection are proposed, implemented using software for regular monitoring and maintenance to ensure reliable operation of the systems under consideration. It is shown that the creation of algorithms and a system is required to detect leaks, including determining their location and scale. The created software can be used for automated control and monitoring of a thermal power system based on the results of the study. Based on the collected data related to the parameters of the heat supply system, such as pressure, gas flow and others, it is possible to build a statistical model that may include the probability distribution, expected values and variances of the parameters. The solution to the problem of specific leak detection may vary depending on the type of heat supply and the technologies used. It is shown that the study will contribute to improving the reliability and safety of heat supply systems by providing more effective detection and control of leaks and other anomalies in the operation of pipeline systems.

МЕТОДИКА МНОГОКРИТЕРИАЛЬНОЙ СРАВНИТЕЛЬНОЙ ОЦЕНКИ ЭФФЕКТИВНОСТИ ЗАМЕНЫ СРЕДСТВ ИЗМЕРЕНИЙ И АВТОМАТИКИ

Ensuring technological sovereignty requires large-scale and massive replacement of foreign technical means in the control and automation systems of many industrial enterprises. This problem is especially relevant for critical infrastructure facilities, in particular energy supply systems and enterprises. The article presents a methodology that allows for a comparative multi-criteria assessment and selection of control and measuring instruments (measuring-and-recording apparatus) for the comprehensive re-equipment of control and management systems of energy enterprises, heat, electricity and water supply systems, industrial and household consumers. The methodology implements an integrated approach to solving the optimal choice problem based on the Data Envelopment Analysis (DEA) methodology. The global efficiency criterion is formed as a result of the convolution of heterogeneous local efficiency criteria of measuring devices, which makes it possible to take into account specific technological requirements for measuring instruments and methods, the specifics of installation and operating conditions of devices. The method of multi-criteria assessment of the effectiveness of the use of measuring instruments significantly speeds up and simplifies the process of objective selection of optimal technical means and reduces qualification requirements for users. The database and algorithm for calculating global criteria can be used to create a decision support system within the framework of automatic design systems.

BUILDING HEAT SUPPLY SYSTEM BASED ON HYBRID SOLAR COLLECTORS

Increasing the efficiency of solar heat supply systems is one of the important problems of solar energy. The research presented in this article is aimed at improving the efficiency of hybrid solar collectors without a transparent coating for building heating systems. One of the key challenges in the field of solar energy is the development of new technologies to ensure high collection of solar energy and to integrate it into traditional heating and hot water systems. The study shows that hybrid solar collectors with the placement of heat carrier circulation circuit tubes above the heat absorber can increase the thermal efficiency factor with a certain change in the angle of inclination and the density of solar radiation. A nomogram was also developed that determines the dependence of this coefficient on the angles of arrival of solar radiation and its density.

Modeling of thermal processes in vertical heat exchangers of ground-source heat pump

The basic directions for perfection heat supply systems are the tendency of transition to the low-temperature heating systems based at application heat pump installations. We consider heat supply systems with ground-source heat pump. The paper considers modeling the efficiency of ground-source heat pumps with the account of Ukrainian climate conditions. The paper presents the energy performance criteria which show the way to rational implementation of ground-source heat pumps for heating. A computational model based at non-stationary heat exchange processes in elements of ground-source heat pumps is developed. Generalization and analysis of theoretical and experimental dates allow establishing nature of dependence thermophysical properties on temperature insoil around ground heat exchangers during long term operation of the system. Numerical simulation of thermal processes in vertical ground pipes for ground-source heat pump working with low-temperature heating systems has been worked out. The results of numerical modeling demonstrated perfection and technical adaption of ground-source heat pump for low-temperature heating systems with rational using ground energy potential. The novelty of our method is complex usage theoretical and experimental results which enable to prevent freezing in the ground during long term exploitation This provides insights at effects of different resource mixes and may serve as a new approach to analysis of future heat pump systems using ground source energy development.The proposed method contributes to the field of creation and implementation the sustainable heating technologies using renewable energy sources. The ground heat exchange pipes quantities that are necessary for effective operation heat pump installation, capacity and coefficient of performance with the account of climate conditions are calculated.

Theoretical analysis and economic evaluation of wind power consumption by electric boiler and heat storage tank for distributed heat supply system

The intermittency and volatility of wind power and the characteristics of the operating mode of cogeneration units pose certain challenges to the wind power consumption of the power grid. To optimize the performance of the power and heat combined operation system and maximize the wind power consumption, this paper establishes a mathematical model for each component of the cogeneration system, including the thermal dynamic characteristics of the heat network, buildings, cogeneration units, electric boiler, and heat storage tank. At the same time, a scheduling optimization model is proposed, which considers the power load demand, and wind power output of the regional heating system. The research results provide insights and optimal dispatching strategies for ensuring the reliable operation of the power system and heating system and realizing the efficient utilization of wind power. This paper verifies the effectiveness and feasibility of optimizing the cogeneration system and provides a practical solution to the challenge of cogeneration economics.

Математическое моделирование потокораспределения возмущенного состояния теплоэнергетической системы

The results of the development of a model for the analysis of the disturbed state of a thermal power hydraulic system on the example of a heat supply system are presented. The parameters of the operating mode of the thermal power hydraulic system after the influence of disturbing factors on it were evaluated. It is shown that the classification of stationary states of the studied fragment of the system with steady flow distribution is oriented to boundary conditions. The boundary conditions classified into four types are considered. It is noted that the choice of boundary conditions must be carried out taking into account the use of energy equivalence in the analysis of the perturbed state of the studied fragment of the hydraulic system. The developed model of steady-state flow distribution with a non-isothermal flow of a viscous medium is presented. It is concluded that the developed mathematical model represents a qualitatively new approach to formalizing the problems of flow distribution analysis in systems with adjustable parameters. The model can be considered as a generalized form of representation of particular flow distribution models when describing the object under study, which can be considered as a hydraulic circuit with adjustable parameters with a non-isothermal flow of a viscous medium. It is shown that this model can be used to analyze and describe the flows and properties of a viscous medium in such systems where it is possible to regulate the parameters, and non-isothermal flow is taken into account.

INTEGRATION OF HEATING SYSTEM OPERATION

Ukraine has a huge asset in the form of existing district heating (DH) networks and demand for related services. DH is transforming the European energy sector, attracting efficient, local and renewable energy resources where this was not possible. However, due to the old material base of spare parts, insufficient level of investment and low level of management, Ukrainian DH systems are ineffective and do not meet the needs of consumers. The experience of European Union member states in central Europe shows that deep and sustained reforms can address the current challenges of the heating sector, including improving energy efficiency and economic competitiveness, strengthening environmental sustainability and enhancing energy security. The DH sector in Ukraine has not yet undergone the structural reform that other sectors of the economy have already gone through: over the past 30 years, the quality of services has decreased; subsidies have increased; the old material base is falling apart; The question arises whether it is worth continuing to support DH. As a result, Ukraine's DH sector is in dire straits, with financial, operational and technical problems compounding each other. Comprehensive and well-planned efforts must be made to create the conditions for exiting this state. Such structural reforms are essential to attracting the investment needed to improve the quality, efficiency and long-term potential of the district heating sector.
 The article examines the possibility of using modern technological solutions to modernize heat supply systems in order to improve their efficiency, which can lead to improved district heating services, transparency and financial stability.
 Keywords: energy resources, renewable energy sources, fossil fuels, automated heat and power plant, electricity, hot water, hot air, heating, private households, electric water heater, geothermal heat pump, wind power generator, low-power boiler house.

Energy Efficiency of Using Hybrid Heating Points in Conditions of Integration of Electrical and Thermal Networks of Urban Neighborhoods. Part 1. Justification of the Feasibility of Using Hybrid Thermal Points

The paper discusses the circumstances and technical solutions that contribute to the integration of electrical and thermal networks of urban neighborhoods within the framework of a surplus of electricity generating capacities arising from the imbalance in the development of energy generation and consumption, stochastic processes of market economy development, the transfer of energy-intensive industrial production to other countries, the desire to diversify fuel energy resources, passion for the construction of energy sources for alternative energy resources in counterbalance to traditional energy facilities without taking into account all aspects of the interaction of the former with the environment, etc. With regard to district heating systems of electrical and thermal networks of urban neighborhoods, the use of hybrid heating points is achieved, which, unlike standard solutions, are equipped with electric boilers, thermal accumulators and heat pumps. According to the time of use of generating capacities, preference should be given to options for covering the hot-water load. Based on the average daily load, the power usage time in this case lies in the range of 6000–6500 hours / year. When choosing the capacity of the equipment, it should be borne in mind that the daily load of hot water supply is extremely uneven and also depends on the day of the week, while the maximum load exceeds the average daily by 2.5 – 3.0 times. When integrating electricity and heat supply systems, it is advisable to consider options for only night-time electricity consumption or night-time consumption plus consumption during the hours of daytime failures of the electricity consumption schedule. If during the new construction the power of the electrical network may vary depending on the selected option, then during the modernization of the heat supply system, the problem is solved if there is a limitation on the available electrical power. Therefore, the definition of these restrictions is a separate issue. In comparison with the direct consumption of electricity for the needs of heat supply, which is a priori energetically and economically inefficient, the use of hybrid systems in heat supply allows us to solve the multifunctional task of increasing the reliability of energy supply and the stability of the functioning of the power system, which is primarily achieved by solving the problem of balancing the capacity of production and energy consumption from the position of aligning schedules of energy generation and consumption.

Technical and economic analysis of a multicarrier building energy hub concept with heating loads at different temperature levels

Integration of renewable and waste energy sources, decentralisation, electrification and energy storage, are key pillars of energy transition in the district heating sector. Such a strategy can be implemented at the building level using the multi-carrier energy hub concept, which has recently gained popularity. This paper presents a technical and financial feasibility study of a building-integrated multi-carrier energy hub concept. The case study is performed for an existing large medical centre, where demand occurs simultaneously for electricity, cold, and heat at different temperature levels, including hot process water and steam. The central idea is to replace the high-exergy steam with heat from the municipal district heating network. The concept also includes the integration of heating and cooling loads, heat storage and implementation of an on-site photovoltaic (PV) power plant. The key components of the proposed hub technological structure are high-temperature heat pumps. Five alternative structures of the system configuration are examined using an hour-by-hour annual simulation. The results reveal that the proposed multi-carrier energy hub is fully operational. The project is also profitable, which results mainly from significant energy savings compared to the existing heat supply system using high-pressure steam. However, the profitability strongly depends on the system configuration, and the choice of the best option is ambiguous. The system with heat storage reaches the highest net present value (NPV) while the one without the storage results in the highest internal rate of return (IRR) due to significantly lower capital expenditures (CAPEX). In all cases, the project leads to a considerable cumulative CO2 emissions reduction, which is at the level of 1351 up to 2961 tons annually depending on system configuration.

НАПРАВЛЕНИЯ ПОВЫШЕНИЯ ЭНЕРГОЭФФЕКТИВНОСТИ СИСТЕМ ГЕНЕРАЦИИ ТЕПЛОВОЙ ЭНЕРГИИ В РАМКАХ ТЕПЛОЭНЕРГЕТИКИ РОССИИ

The article discusses the directions of improving the energy efficiency of heat generation systems involved in solving heat supply problems in the Russian Federation. The thermal energy generation system is considered as a set of subsystems of heat generating equipment, movement of gaseous media, preparation and transfer of coolant, reduction and disposal of emissions. Each subsystem consists of corresponding elements. The energy efficiency measures under consideration are analyzed in accordance with the impact on the impact element, other elements of the subsystem, the heat supply system as a whole, as well as other energy supply systems. Due to the importance of environmental problems, as well as the need to optimize the generation of thermal energy by reducing losses at the stages of production, transportation and consumption, elements related to the reduction and disposal of emissions, including thermal pollution of the environment, are allocated to a separate subsystem of the heat generation system. The necessity of a comprehensive consideration of the heat generation system, along with related power supply and energy consumption systems, is shown. Inventory of energy flows, comparison of the actual with the necessary and sufficient amount of energy allows you to determine the possible and necessary ranges of regulation of elements of subsystems of the thermal energy generation system. Due to the large technical wear of heat generation equipment and significant changes in the connected heat load, the need for the development of energy-efficient tasks for the design of reconstruction and new construction of heat generating facilities by start-up complexes is increasing. This makes it possible to achieve the objectives of improving energy efficiency after each stage of reconstruction or construction, as well as to carry out long-term and high-quality planning.

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.

Modeling and economic evaluation of deep geothermal heat supply systems using the example of the Wealden near Hannover, Germany

Germany desires to become climate-neutral in its heat supply by 2045. From 2024 onward communities are legally required to develop a plan documenting how the objective will be achieved. Geothermal resources can be a major building block to reach the aspirational target if they can be developed at competitive costs. To evaluate the economic potential of geothermal resources is time and money consuming. Questions which need to be addressed in the context of such evaluations are: how can an economic recovery of geothermal heat be achieved, how can subsurface risks associated with an exploration be managed, and how competitive is a deep geothermal energy recovery compared to other options of heat supply? These questions are key to a development of deep geothermal heat, especially if the geothermal conditions are not as prominent as in already realized projects, but less favorable as in the deep clastic sediments of the North German Basin. With this contribution a procedure is presented and used to determine net present values and the associated levelized costs for deep hydrothermal heat recovery systems. It consists of modelling the geothermal cycle, sizing all necessary components, costing them, and calculating net present value and levelized cost. The thermal model is verified by comparing the modelled state variables pressure and temperature at relevant state points of the thermal cycle with actual data of a geothermal project. The cost model is validated with biding results and cost information from actual projects and modified as appropriate. In applying the model to a setting in the Hannover–Celle area with temperatures of around 70 °C, conditions are determined, which lead to positive net present values. The degree of their influence is determined in sensitivity analyses allowing a systemic optimization. The results show that for a coupled heat plant with geothermal heat supplied at baseload conditions, levelized costs of approx. 8 cents/kWh are achievable. The presented thermodynamic and cost models are considered helpful instruments for developing preliminary conceptual estimates, strategies for optimization, and portfolio management.

Аналіз сонячного промислового теплопостачання

The future of Ukraine is only impossible without integration into the European community, including in the fight against climate change. It is possible to make the production of thermal energy more environmentally friendly thanks to the introduction of solar technologies. Solar thermal technologies are necessary for the decarbonization of the industrial sector. Information from open sources on the state and prospects for the development of solar industrial heat supply systems in the world has been analyzed. Analysis of the development of solar heat and steam production for industry in the world has shown that the solar thermal energy market is currently in an early stage of development, but it is actively developing and many projects will be commissioned in the near future. Specific investment costs and economy of solar industrial heat supply systems of various capacities are determined. The average weighted cost of thermal energy for the life cycle is used as a criterion of economy in world practice. Specific investment costs for installing solar systems are significantly reduced when their thermal power is increased. Approximate dependences of average specific investment costs on thermal power were obtained. The specific investment costs of installation and the number of hours of operation significant impact on the average cost of solar heat and steam production for industry. Approximate dependences of the average cost of heat on thermal power at different discount rates and at different power on discount rates were obtained. In Ukraine, it is possible to organize the supply of industry with heat and hot water from the use of solar technologies in a short period of time. A promising direction is the use of solar heat supply systems in combination with other thermal energy sources. Keywords: thermal energy; industrial heat supply, powerful solar systems, investment costs, cost of thermal energy.

ON THE ISSUE OF ENSURING THE MICROCLIMATE CONDITIONS AND OPERATIONAL SAFETY OF HEAT SUPPLY SYSTEMS DURING EMERGENCY HEAT SUPPLY SHUTDOWNS

The issue of ensuring the microclimate conditions of the premises in the buildings and structures during cold season are of exceptional importance, as it is the basis for ensuring the safety of human life and health. Emergencies and significant violations of the thermal regime in premises and buildings worsen microclimate conditions for an indefinite period of time, until its parameters reach extreme values dangerous for human life. These issues are particularly relevant in the context of the growing number of emergency situations in heat supply systems in Ukraine, both due to the high level of wear and tear of their infrastructure in general, and wartime emergencies. Therefore, conducting research to ensure the safety of heat supply systems operation during emergency shutdowns by determining the regularities of temperature changes in rooms, reaching the critical temperature and operating time of heat supply systems, taking into acount the spatial location of rooms in buildings and their design features, is an urgent task. The purpose of the article. Study of the risk of reaching critical modes of heat supply systems operation in emergency situations, taking into acount the structural features of buildings and ensuring the necessary microclimate conditions. Conclusion. On the basis of the conducted research, the regularities of the structural features of buildings and structures in emergency situations in heat supply systems to ensure microclimate conditions in the premises have been determined. The limit conditions for achieving critical indoor microclimate conditions due to accidents in heat supply systems are determined, which allows predicting the limit conditions for eliminating the consequences of emergency situations and optimizing the activities of repair and rescue services, which is especially important in connection with the failure of outdated heat supply systems and combat operations on the territory of the country.

Моdern heat and steam supply systems of industrial enterprises using deep utilization of the technological steam energy potential

Steam supply systems of industrial enterprises, as a type of heat supply system, are a large consumer of primary energy in national energy balances. In turn, due to the specificity of thermodynamic steam processes, steam supply systems of industrial enterprises in practice have significant unused potential of secondary energy resources (SEP). Modern steam supply systems should be built exclusively when evaluating their exergetic efficiency, which will make it possible to evaluate the effectiveness of such systems grossly in all elements of the life cycle of the project: energy, economic, ecological and even social. The article shows modernized thermal schemes of steam supply systems, for which it is possible to achieve additional electrical power at the level of 135-250 kW/(kg/s) when devices with a relative internal efficiency of up to 60-70 % are operating. In combination with an increase in the percentage of condensate return and the utilization of secondary energy resources (SRP), the increase in energy efficiency of the system is 2-4 %, and the absolute value of exergetic efficiency is 16-22 %, taking into account the exergetic efficiency of the boiler unit. Low-potential "tail" consumers: the heating system, the hot water supply system - increase the exergy efficiency of the steam supply system of an industrial enterprise by 0.2-0.6 % in the case of joining on the steam side of secondary boiling. Any processes of generating electrical energy are associated with obtaining a significant amount of thermal energy, and must be accompanied by its utilization; enterprises that use steam as an energy carrier (the same applies to energy enterprises such as thermal power plants and nuclear power plants) for the deep utilization of hydroelectric power plants must have thermal energy consumers in their composition, which can act as communal household consumers (if they exist), as well as new technological consumers of thermal energy.