A brief analysis of the state, problems and external conditions of operation of combined heat and power plants in Ukraine, as well as their changes during hostilities. Issues and proposals for the choice of rational modes of operation of CHP in the conditions of primary fuel shortage, reduction of electrical loads of the energy system, the risk of possible damage to energy equipment during hostilities and in the postwar recovery. It is proposed to develop and implement in the practice of planning the development of survivability criteria of stations with connected district heating systems. References 7, figures 4.

The main features of energy and exergy methods of analysis the energy transformations efficiency in typical heating systems (boilers, electric heating, heat pumps with electric drive) are presented. The equations of energy and exergy balances of systems and their elements are made. Based on them, expressions for calculating efficiency indicators are obtained. The results of calculations and comparison of energy conversion coefficients (COP - Coefficient of Performance) and exergy efficiencies (Exergy Efficiency or Second Low Efficiency) are presented. It is shown that heating systems based on fuel boilers and electric heaters are characterized by high COP values, which does not focus on taking measures to improve them. At the same time, such systems have rather low values of exergetic efficiency. It is shown that exergy efficiency of a typical electric heating system reaches about 3%, and heating based on fuel boilers - about 6,5 %. The analysis of the main reasons of thermodynamic irreversibility in the specified systems is executed. The diagram of changes exergetic efficiency in consecutive elements of a typical heating system on the example of a fuel boiler room is given. It is shown that in a fuel boiler the main irreversibilities occur at the stages of combustion and heat transfer at a large temperature difference. In electric heating systems, the main exergy losses occur during the production of electricity at thermal power plants and during the conversion of electricity into heat in electric heaters. Possibilities and main ways to reduce the thermodynamic irreversibility of the heating system from the steam boiler house during its conversion into a mini - CHP are considered. The analysis of thermodynamic losses in heat pump heating systems is performed. The conditions under which such systems become more energy efficient than systems based on fuel boilers are defined. The reasons for the wide practical application of boilers and electric heating are revealed, despite their low thermodynamic perfection.

Background. Currently, in the cycles of steam-ejector refrigeration machines (SERM) are used monoagent jet compressors, the working body in which is water. Despite their low efficiency, SERM have a number of advantages over refrigeration machines that usemechanical compressors: low cost, ease of manufacture and reliability. The use of SERM is largely limited by the inability of these installations to reach temperatures below 0 °C. This limitation can be overcome by applying a fundamentally new steam compressioncycle using a bioagent (water-freon) jet compressor (BAJC).Objective. The purpose of the paper is experimentally confirm the operability of a refrigeration machine operating on a steam compression cycle using a bioagent (water-freon) jet compressor. Determine the efficiency of the experimental refrigeration machine andfind the optimal geometric characteristics of the jet compressor.Methods. An experimental stand was created to study the refrigeration plant using BAJC. The refrigeration machine efficiency e was determined according to the developed method.Results. Experimental values of the cooling machine coefficient e were obtained depending on the change in the ejection coefficient q of BAJC. The maximum machine coefficient values emax = 1,3 ÷ 1, 4 correspond to those of the ejection coefficient q opt ≈опт 0, 25q 0,25, which also achieves the maximum efficiency h ≈max 0,35 ÷ 0, 45 of the BAJC.Conclusions. The efficiency of a refrigeration unit operating on a steam compression cycle using a bioagent (water-freon) jet compressor has been experimentally confirmed. To expand the temperature spectrum of the cycle in the direction of lowering the boilingpoints in the evaporator (tboilt −≤кип 20 °C), it is planned to modernise the laboratory bench by using aqueous salt solutions as a coolant.