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Currently, a lot of attention is paid to the issue of using renewable energy sources. This is primarily due to the fact that they can become a solution to emerging problems that cause global climate change and depletion of fossil natural resources. The purpose of the work is to analyze the technical solutions of solar power plants and the issue of their use in Russia. To solve this problem, various materials of domestic and foreign scientific articles on the subject of solar energy were systematized: the main types of solar power plants, the features of their operation were considered, the advantages and disadvantages of various systems were identified. It has been established that of all types of renewable energy sources, solar energy is the fastest growing. The use of solar energy follows the path of two main directions: the production of thermal and electrical energy. At the same time, the solar electric power industry is the most active and promising area of numerous scientific research on the scale of already implemented projects. It has been established that the territory of Russia has certain geographical zones with great potential for the development of solar power plants, which will allow converting incident radiation directly into electrical energy. This fact is confirmed by the already implemented unique projects that are located in these zones.

Objectives The aim of the study is to generalise the results of the application of technologies and means for organising pulse coolant flow within a district heating system in order to increase its energy efficiency based on the organisation of local hydraulic shocks and the subsequent use of their energy to ensure the purification of heat energy equipment, intensify the heat transfer process and realise the possibility of transforming the available head from one hydraulic circuit to another. Methods Substations connecting the thermal power installations of consumers with heat networks via dependent and independent schemes are analytically generalised. The use of pulse coolant circulation is proposed as a means of overcoming identified shortcomings. Results Principal schemes of substations with pulse coolant circulation for dependent and independent connection of thermal power installations are detailed. A detailed description of their operation is given. The advantages of using pulse coolant circulation in substations are shown. The materials reflecting the results of the technical implementation and practical introduction of this technology are presented. Conclusion Theoretical analysis of the operation of the basic schemes of substations with pulse coolant circulation and the results of their practical application, as well as the materials of scientific works devoted to the use of the energy of a hydraulic impact and the study of the effect of pulse coolant flow on thermal and hydrodynamic processes, have yielded a combination of factors reflecting technical and economic rationality of application of pulse coolant circulation.

The aim is to justify the expediency of a transition en masse to independent connection of heat consumption systems under the conditions of pulse circulation of the coolant through the equipment of a heat supply unit in order to increase the overall energy efficiency of district heat supply systems. Methods. The research is based on methodologies for the effective use of technologies providing a means of effecting a pulsed motion of the coolant in the heat supply system. The advantages and disadvantages of known technical solutions are identified and summarised. Hydraulic accumulators or any other devices for damping a hydraulic shock can be used as devices for preventing the propagation of a wave of hydraulic shock into the transport mainline. Results. An analysis of approaches to heat consumption system connection is carried out in order to assess power efficiency; the most effective ways for improving the efficiency of heat and power devices are identified; a synthesis of the technical solution for the implementation of a technological connection of heat consumption systems is performed. The expediency of transition to independent connection of heat consumption systems under the conditions of pulse circulation of coolant in heat supply units is demonstrated. The independent scheme of connection of subscribers to the heat network is indicated as the most appropriate. The factors constraining the en masse transition to independent connection of the heat load are determined. Based on the analysis and scientific research in the field of increasing the energy efficiency of heat and power systems, the transition to pulse circulation of the coolant in the heat supply unit of the independent heat consumption system is selected. The presented technical solutions are confirmed by Russian Federation patents of inventions and utility models. Conclusion. It is shown that the use of pulse coolant circulation in the equipment of heat supply units for independent connection of heat consumption systems will increase the reliability and long-term operation of the recuperative heat exchanger, as well as increase the overall energy efficiency of the heat supply system.

Objective. The aim of the work is to study the use of nanofluids as heat carriers to increase the efficiency of heat removal in energy facilities. To solve this problem, materials of domestic and foreign scientific articles, conferences and dissertations on the subject of nanofluids were analyzed. Numerous scientific publications, including those cited in the international databases Web of Science and Scopus, indicate that the topic of nanofluids is in the focus of modern science. However, despite a rather long period of fluid research, not all issues of this topic are sufficiently well covered and systematized, which opens up great opportunities for further research in this direction.Method. When achieving this goal, the areas of possible application of fluids, the mechanism of their synthesis, the features of their operation are considered, the advantages as a liquid coolant are indicated, and the disadvantages that prevent their widespread use are identified. Particular attention is paid to such issues as: synthesis of standardized nanofluids; ensuring their stable properties; the use of surfactants; increasing the pressure drop inside heat exchangers during operation of this coolant.Result. To eliminate the main drawback in the form of agglomeration of nanoparticles in the base fluid, it is proposed to use the oscillatory circulation of the coolant, which will also further intensify heat exchange from forced turbulence of the fluid.Conclusion. The results obtained can be used to improve the efficiency of heat and mass transfer devices with liquid coolant and systems based on them, as well as to reduce the weight and size parameters of such devices.