The volt-ampere characteristics of different diodes and zener diodes are obtained experimentally, and they differ significantly from experience to experience. It is unclear how to properly substantiate the reason for such differences. In this regard, a problem arose in developing the theoretical foundations for the production of this type of equipment on a sufficiently sound theoretical basis, taking into account the latest advances in electrical engineering and electronics. As a consequence, the process of formation of conduction currents and displacement currents in a metal–semiconductor contact is considered. Aluminum was used as a metal, and germanium and silicon were used as a semiconductor. With a direct applied external voltage, a theory for calculating the volt-ampere characteristics of germanium and silicon diodes has been developed. It is shown that the affinity energy of atoms of semi-conductor materials at the cathode increases slightly due to the coupling of negative ions with electric dipoles of atoms of the surface layer of aluminum molecules inside a columnar void, and an electric conduction current is formed by the movement of electrons from the cathode to the anode. The electron concentration due to the ionization of negative ions is determined not by the temperature of the diode itself, but by the reduced temperature of the electron gas inside the aluminum due to overcoming the contact potential difference at the p-n junction. A sequential accumulation of negative electron charge occurs at the anode, which determines the conversion of the conduction current into a displacement current, since the electron energy in this case does not exceed the energy of the aluminum work function of the crystal. At the reverse applied voltage, the affinity energy of the negative ions of the impurity atoms at the anode remains the same due to the ionization of the negative ions, taking into account an increase in the temperature of the electron gas at the p-n junction with an increase in the displacement current. An electric conduction current arises from an aluminum crystal acting as a cathode inside a columnar void due to thermoautoelectronic emission. The conduction current at the anode is converted into a displacement current, which enters the external electrical wires. The inner walls of the columnar void are a good dielectric and therefore they sufficiently conduct displacement current inside the columnar void. The conduction current in this case acts as an amplifier of the resulting electric current.

A method for calculating non-stationary thermal processes in wires for low-voltage overhead power transmission lines is proposed. The technique is based on the representation of a wire as a system of several homogeneous bodies and the solution of differential equations describing this system. The equations are solved by the method of electrothermal analogies based on the thermal substitution circuit and the Laplace operator transformation. Formulas are given for determining the power losses in the wire, thermal resistances and heat capacities of the wire. Special attention is paid to calculating the coefficient of heat transfer from the surface of the wire. Algorithms for calculating the temperatures of single-core and multi-core wires when influencing external factors change have been developed. It is shown that the temperature calculation must be performed in several iterations. The concept of heat exchange angle is introduced, characterizing the part of the wire surface through which heat exchange takes place. Experimental studies for different brands of wires at different currents have shown that the maximum absolute error of the calculated insulation temperature of the wire relative to the measured temperature is no more than 6 °C. For the long-term allowable currents in the wires of the SIP-4 brand (‘self-supporting insulated wires’), the values of the reduction coefficients are calculated depending on the number of cores. For example, for the SIP-4 4x16 wire, the permissible current should not be 100 A, as given in the directories, but 80 A at an ambient temperature of 25 °C. The calculation methods and algorithms presented in the article can be used to estimate the capacity of low-voltage electric networks, as well as at the design stage of power supply systems.

The development of the electric power industry is accompanied by the improvement of diagnostic tools for the state of equipment in energy systems. Some of the electrical network equipment is significantly worn out and requires increased attention in order to determine the residual resource. The synthesis of intelligent technologies and generally accepted diagnostic methods is the next step towards the future of the electric power industry. The aim of the project is to develop the principles for the functioning of an automated processing system for results of thermal imaging diagnostics of electrical equipment. The paper examines the criteria for evaluating defects in electrical equipment based on the heating temperature. An algorithm for automating the processing of the results of thermal imaging diagnostics of electrical equipment is also being developed on the basis of artificial neural networks. The software implementation of the detection of electrical installation elements in infrared images is performed using the YOLOv5 architecture. Testing and evaluation of the trained neural network are performed using thermal imaging diagnostics data of working electrical equipment. The neural network model trained as part of the study demonstrates confident detection of electrical installation parts based on the results of detecting thermograms from a test sample. Based on the results of the analysis of regulatory documentation, an approach to determining the degree of defect development has been clearly laid out. In addition to using thermal images of electrical grid equipment, the current load and ambient temperature are also recorded to select a suitable formula for calculating temperature excess or excessive temperature of an electrical installation unit or contact connection. The developed algorithm for automating the processing of the results of thermal imaging diagnostics of electrical installations based on the YOLOv5 neural network reflects the main processes necessary for the functioning of the system. A custom dataset was generated and marked up, including thermograms of real-life electrical installations, on the basis of which a neural network model was trained. Using a test sample, we were able to calculate the values of metrics to evaluate the quality of YOLOv5 model learning. The developed system has been tested on thermograms of electrical equipment. Its use makes it possible to identify not only the developed defects, but also the initial stage of the occurrence of defects in an automated mode.

Increasing the efficiency of primary energy sources use in the production of heat and electricity at thermal power plants is an enduring task in the context of reducing the cost of converted energy flows production and improving the environmental characteristics of a power gene-rating unit. To solve this problem, it is proposed to develop a system for regenerative heating of feedwater via the use of low-temperature waste heat flows from a thermal power plant, which is possible with the integration of heat-recovery heat pumps into the thermal scheme of the station. In this paper, we consider the use of the aforementioned lithium bromide absorption heat pumps driven by flue gases extracted from the steam boiler path and the circulating water stream of the condenser is used as a source of low-potential energy. Depending on the efficiency function, when optimizing the operating mode of the power plant in accordance with the requirements of the power system after modernization, it is possible to reduce the electric power of the turbine, increase it or maintain it at the same level. For each of the three variants, a numerical experiment was conducted for the PT-60 turbine unit, which is the most common in the unified Belarusian Energy System. For the option with a decrease in electrical power, the following results were obtained: an increase in electrical, energy and exergetic efficiency, respectively, amounted to 4.3, 2.6 and 1.1 %, while also reducing the temperature of outgoing flue gases due to their deeper cooling to 110 °C. The paper determines the cross-sections of the gas-air duct of the boiler unit for the selection of flue gases with a temperature that ensures the operation of the absorption heat pump at nominal parameters. The flue exhaust gases of the lithium bromide absorption heat pumps are mixed with the flue gas stream directly from the boiler before being discharged into the smokestack.

Adsorption materials based on natural minerals are considered in the world literature as inexpensive hydrogen sulfide adsorbents capable of completely replacing commercial products such as synthetic zeolites. The global demand for inexpensive, accessible, safe materials is growing, including in the field of cleaning industrial and agricultural gas emissions from hydrogen sulfide. The article presents an analysis of literary data on natural clays, activated sludge and other materials and methods of their use for hydrogen sulfide adsorption. Data on the composition of activated sludge, clays and limestone rocks are provided. The composition studies were carried out on an infrared spectrophotometer. The inorganic component of activated sludge includes iron oxide, aluminum, calcium, magnesium compounds, and silicates. Limestone consists of carbonates, iron oxide, silicates, and when calcined at high temperatures, it mainly forms calcium oxide. Various clays contain aluminosilicates, iron oxides, copper, cobalt, and manganese. Due to the content of metal oxides, natural materials have a chemisorption mechanism, and due to the content of aluminum and silicon compounds, they have a physical sorption mechanism. 17 compositions of composite materials from natural minerals were developed and their sulfur content was studied. A study was also conducted on the absorption capacity of activated sludge in a liquid state. It was shown that all natural materials have a high potential for use as adsorbents with minimal preparation (dehydration, calcination). Compositions that do not contain expensive additives, consisting mainly of сalcined limestone rock and clays, showed sulfur capacity from 10 to 40 %.

The article presents the results of research, during which using the example of the climatic conditions of the Kashkadarya region (Republic of Uzbekistan) a methodology has been developed to increase the energy efficiency of double-slope solar greenhouses. A literature analysis has shown the potential for energy savings in the greenhouse farming of the agribusiness. At the same time, it is shown that, despite the extensive research carried out in a number of countries in this area, it is necessary to continue studying the problem of putting into practice the parameters of their orientation on the terrain for various geographical regions to maximize the perceived total solar radiation. The paper presents an analysis of the research results on the dependence of the total solar radiation incidence on a gable glass-roofed greenhouse with a usable area of 50 m², a wall height of 2 m and a roof slope height of 1.5 m on the design parameters of the latter and the trajectory of the sun. The simulation of the solar greenhouse operation modes was carried out in the MATLAB package, taking into account changes in the environmental parameters of the area in the period from November 15, 2023 to March 15, 2024 with a latitude of 38.87° and an orientation from 0 to 90° with an interval of 5°. As a result of the simulation, the optimal parameters of the greenhouse were determined for the above period (azimuthal angle of the surface γ_opt = 45°, angle of inclination of the surface β_opt = 50°) with the maximum total solar radiation for the specified period equal to ∑I_max = 35660 MJ, which exceeds by 20% the radiation for a standard-sized greenhouse. Generalization of the simulation results made it possible to develop a methodology for determining the geometric characteristics (dimensions and orientation parameters) of solar gable greenhouses with specified climatic conditions according to the criterion of maximizing the incident total solar radiation in winter, which can be extended to other regions of Uzbekistan in order to increase the energy efficiency of the agribusiness sector.