Optimization of technical and economic parameters of electric power storage devices is a necessary condition for their widespread use. The article develops a general approach and proposes a methodology for assessing the economic efficiency of hybridization of electrochemical energy storage systems (ESSs). From the point of view of evaluating the effectiveness of storage hybridization, a number of model systems operating under different load conditions using different block functional interaction schemes are being investigated. Lead-acid batteries supplemented with lithium-ion batteries; lead-acid batteries supplemented with supercapacitors and lithium-ion batteries supplemented with supercapacitors are considered as the basic types of hybrid storage devices. An electric forklift, a 30-apartment residential building, as well as a 300-apartment residential complex are considered as the load of the ESS. A quantitative and qualitative model for evaluating the effectiveness of hybridization is used, based on comparing the cost of buffering electricity by each type of battery and the hybrid drive as a whole. For all cases, economic indicators characterizing the cost of buffering electricity by hybrid ESSs are calculated and the advantages of a particular scheme of interaction of hybrid ESS blocks are analyzed. It is shown that the hybridization efficiency demonstrates a complex nonlinear dependence on the degree of hybridization, the type of which depends both on the type of batteries used and on the nature of the load schedule, as well as on the type of functional interaction of the blocks. A specific feature of this dependence is a sharp increase in economic efficiency at small values of a £ 0.01 and a further slowdown in the growth or fall of the graph. The obtained results make it possible to quantitatively compare the efficiency of the hybridization of the ESS for specific conditions of its operation. The considered models and methods can be used in the design of ESSs and “generator – storage – consumer” systems, assessment of the economic feasibility of hybridization of ESSs.

The purpose of the study was to test the hypothesis of the existence of an optimal ratio of the installed capacity of solar and wind power plants, which allows, with a large installed capacity of renewable energy sources with a variable nature of operation, to minimize the impact of their generation on the operation of the power system and reduce the capacity of energy storage devices when they are used in the system. The following tasks were set: on the basis of meteorological data, to calculate hourly energy generation by complexes of solar and wind power plants of various combinations of capacities for several years, analyze the generation and, if the hypothesis is confirmed, find the optimal ratio of capacities. In the course of the study, modeling methods and numerical methods for solving optimization problems were used, viz. the iteration method and the nonlinear least squares method. The optimal range of the ratio of solar and wind power plants installed capacities in a separate complex and in the whole power system for the conditions of the Republic of Belarus was determined, which was 0.4:1–0.6:1 (sun:wind). Complexes of energy sources with a power ratio in the specified range can reduce the required capacity of energy storage systems compared to the capacity for only solar or only wind power plants by 2.6–4.0 times, which leads to a reduction in capital costs and the payback period of the project. Going beyond the recommended range leads to a pronounced surplus or shortage of electricity generation in different periods of the day of different periods of the year, depending on the ratio of installed capacities. Also, the optimal specific capacity of energy storage systems for complexes consisting of solar and wind power plants in the installed capacities recommended ratios was determined, which amounted to 0.4–0.8 kW×h/kW of total installed capacity.

An autonomous system of passive removal of residual heat (PRRHS) of a reactor installation with VVER designed to ensure the safety of nuclear power plants in an accident with complete long-term blackout is considered. The system provides for the removal of heat directly from the first circuit of the reactor plant (PRRHS R). In order to increase the reliability and safety of the emergency heat sink, heat exchange equipment based on closed-type evaporation and condensation devices – two-phase thermosyphons – has been used in the system. The main feature of such heat exchangers is that their thermosiphon assemblies structurally separate the primary circuit and the auxiliary circuit of the PRRHS, which is removed outside the reactor compartment, and provide safe and efficient heat removal, reduce the risk of radioactive contamination spreading beyond safety barriers. Such autonomous passive systems will provide effective heat removal directly from the primary circuit by changing the chain of successive heat transfer sites from nuclear fuel to the final absorber and excluding from it such elements, as for example steam generators, the condition and operability of which in the emergency process of heat removal have a major impact on the safety of the reactor core. The article presents a diagram of an autonomous heat sink system; also, a description of its operation is given. The main characteristics of the course of the emergency process of removal of residual heat by the autonomous thermosiphon PRRHS R obtained by computational modeling have been considered. The advantages of an autonomous thermosiphon passive system in comparison with a passive heat removal system of a reactor installation with VVER through the second circuit are analyzed. The obtained results are proposed to solve the problems of diversification of passive safety systems of evolutionary reactor plants of nuclear power plants with VVER type reactors.

One of the most important aspects of a “smart home” is its heating system, which should provide comfortable living conditions for residents while also being energy-efficient. This article discusses an innovative approach to heating systems in “smart homes” based on centralized heating with the utilization of secondary energy resources using a heat pump. The proposed heating system combines the advantages of traditional centralized heating and the efficiency of heat pumps. The article presents a calculated scheme, for which a temperature chart was developed. A methodology for calculating heat loads for both the traditional heating scheme and combined heat and power (CHP) with heat pumps is also proposed, and the necessary calculations were carried out. For clarity of the obtained data, a graph depicting the total steam load required for heating as a function of ambient temperature is constructed, as well as a graph showing the steam load as a function of the duration of the ambient temperature. The analysis of the data revealed that the use of heat pumps in CHP schemes reduces electricity generation by eliminating its production in the steam flow in the condenser. This facilitates the coverage of the electricity consumption schedule during periods of low demand for the integrated energy system. Additionally, integrating a heat pump into the heating system of the centralized heating system helps reduce energy dissipation and greenhouse gas emissions into the atmosphere, making heating more sustainable and environmentally friendly. Moreover, the proposed heating system for a “smart home” demonstrates high technical and economic performance, ensuring the investment attractiveness of such a project.

The results of the study of heat treatment in the drying processes of thin thermal insulation materials based on the most general laws of convective drying of wet bodies with the establishment of the equation of the drying curve are presented. The numerical values of heat and mass transfer Biot numbers for the period of decreasing drying rate are established, too. Based on the study and analysis of numerous sources, the ranges of changes in the Lykov, Posnov, and phase transformation criteria for the processes of heat treatment of ceramics, asbestos, felt, and clay plates have been approximately determined. It is demonstrated that for values of Biot numbers less than one, for Lykov criteria value of 0.05–0.13 and for Posnov criteria value of 0.03–0.08 for drying modes with a temperature of 90–120 ° C, the task of drying, as a heat and mass transfer process, is external, and internal transfer does not affect the conditions of interaction of the material surface with the environment. It is also shown that the drying of thin materials takes place when the Biot number is less than one and, under the conditions of an external problem, the similarity criteria do not affect convective drying. The intensity of moisture evaporation from the body surface is determined by the value of the heat transfer coefficient in the Biot number and the regime parameters of the process. It has been established that the processes of drying materials are low-intensity processes. Based on the elements of the theory of thermal regular regime, the rate of heating of a wet body and the rate of decrease in moisture content are determined. The problem of constructing drying curves without conducting experiments to determine the duration of drying of thermal insulation materials based on approximate equations is considered; this problem is of interest for the practice of drying. The constructed drying curves do not coincide with the actual curve with an error of 4–5 %.

When designing power plants of a new type or equipping them with new generation equipment, the problem of estimating capital investments is solved with the uncertainty of information on its cost. The lack of reliable methods suitable for use in engineering setting complicates decision-making on the technical development of power units and thermal power plants. When evaluating investments in the equipment of power plant units, it is convenient to use continuous functions. Their use makes it possible to carry out the analysis without cost restrictions. The article proposes a method for estimating capital investments in the boiler island of power units of power plants based on a power parametric function. The method includes an assessment of the cost of a boiler unit with fuel preparation systems within the boiler shop, draught and blast. A specific feature of the method is that the cost of the boiler includes the cost of flue gas purification systems from harmful combustion products in the form of ash, sulfur oxides and nitrogen oxides. The method was developed in an engineering setting. The methodological section demonstrates the performance of the method in assessing capital investments in a boiler island in comparison with the same indicator for the EU countries, the USA and China. When discussing the results of the study, it was found that capital investments in a coal-fired boiler with flue gas purification systems is in the range of US$ 25–200 million, depending on the power and initial steam parameters. The share of the cost of environmental flue gas purification systems is 28–50 % of the total cost of the boiler unit. It is demonstrated that the design of coal-fired power units with flue gas purification systems for supercritical parameters with a capacity of less than 300 MW is inefficient due to low competitiveness in terms of specific investments in the boiler.