Calculating of wires sag and tension under various modes is the task of mechanical calculation. The article derived formulas for the curve of the wire sag under the action of one or several concentrated forces and with various tensioning insulators strings in the span. Formulas for estimating the distance to the maximum sag have been obtained. Based on the length of the system of “first tension insulators string – conductors – second tension insulators string” that depends on the supporting beam reactions and beam lateral forces in the corresponding sections, the system load factor was determined taking into account structural elements for different climatic loads. The formulas to calculate the load factor for solving the equation of state in the case of different insulators strings in span loaded with one or several concentrated forces have been obtained. The resulting expressions can also be applied in case of horizontal wind loads; in this case the equation of state should take this component into account when calculating the resulting reduced load on the wire in an inclined plane. The reliability of the formulas was proved by the coincidence of the results for the particular case of the arrangement of the insulators strings. An algorithm for calculating sag under the combined action of vertical and horizontal loads, as well as in the case of the location of wire suspension points at different heights, is given. A formula has been proposed for estimating the sag increase factor due to the presence of concentrated forces uniformly distributed along the span and various insulator strings in the span. The dependence of the coefficient of increase of the sag on the distance to the concentrated force in the presence of one and two forces in the span is drawn.

The necessity of improving the power supply system in the agricultural sector is substantiated by the growing share of first-category loads that require targeted reliability. Improving values of the technical and economic indicators of centralized energy generation and its transmission through main and distribution grids cannot ensure high reliability of consumers of the first category, the number of which is constantly growing in agriculture. It is noted that if the power system in outage of the generating source of the high power supply is provided by inputting the emergency reserve, then at emergency switching-off phase of the section of the mains, power supply of the consumers powered by the schemes for both radial and looped distribution network may be absent for a long period of time (several hours). The ways and methods of improving the power supply system, such as integration of a single power system with distributed generation sources, ensuring their parallel operation, load management using complex tariffs for electric energy that take into account the form of load schedules, modernization of technological processes taking into account their automation and improvement of technical and economic indicators, are considered. Taking into account the increase in electricity consumption for heating and hot water supply, we consider the option of eliminating cross-subsidization, which stimulates the interest of consumers in saving electricity and reducing the fee for electricity consumption by changing the operating modes of equipment and devices. The analysis of promising energy-saving measures in agricultural power engineering demonstrated that routine measures are being supplemented by other measures induced by the fact that power electronics and microprocessor technology have significantly advanced in their development in the agricultural energy sector over the past decades, for example, for frequency control of asynchronous motors equipped by a short-circuited rotor that has high values of energy and dynamic indicators. Since there are a number of technologies in agriculture where electric energy is used without the electric drive units application and each of the technological processes has its own requirements for the reliability and quality of electric energy, the scheme of mutual redundancy from adjacent substations using distributed generation sources and technical means of automated energy accounting, control and management of electrical loads, is considered.

The active development of the mobile platforms sector such as smartphones, smart watches, fitness bracelets and other wearable electronic devices in the last 4 years has caused a huge growth of the market of mobile applications-services. Western countries are actively implementing mobile applications-services for household energy users. In Belarus, there is a positive dynamics in the number of active users of applications-services, every year it is possible to attract 7 % of unique customers. In the present paper the experience of implementation and operation of the mobile application for power systems is analyzed. The dynamics of the market of mobile applications-services has been traced: the amount of time spent by the person in interaction with the device was determined as well as the total expenditure of funds in the application at the moment; also, the growth of expenses within the applications was forecasted. The potential benefits for business and end-users of services from the implementation of mobile applications-services were demonstrated. Their properties, main qualities and advantages over traditional methods of “business – client” interaction are considered. A number of features needed for the successful functioning of the mobile application in the power system of Belarus are identified. The process of creating software for smart devices has been studied and the functionality needed by the mobile application for the power system has been proposed for attracting new users. A special algorithm for the launch and successful “life cycle” of a mobile application has been proposed. It allows to operate and develop mobile applications-services as efficiently as possible, as well as to avoid the most common errors at the stages of their development and launch. The implementation of a mobile application in the power system of the Republic of Belarus, in the long-term, will significantly increase customer loyalty, simplify interaction with users, make it possible to build new models of distribution of electricity, and, consequently, regulate the demand for energy resources.

Air cooling devices are heat exchange units that are widely used in practice. However, they have a number of disadvantages due to the low value of the heat transfer coefficient from the air and the high resistance of finned tube bundles, which leads to large dimensions and the metal content of the device itself, to the need to develop a high power ventilator drive, but also to the need to demonstrate reduced energy efficiency. The objective of the present work is to determine optimal geometric sizes of finned flat heat exchange tubes manufactured by the techniques of extrusion and deforming cutting that reduce the weight and size characteristics of the heat exchange section of air cooling devices. The experimental studies of seven various samples of heat exchange sections, being different in fin pitch and height, tube section width, flat tube height and a number of inner channels, have determined the performance of each section with the use of the following criteria: thermal power, thermal efficiency, specific thermal heat transfer resistance, M. V. Kirpichev and V. M. Antuf’ev’s criteria. The obtained experimental data and the analysis of the passive method of enhancement in the near-wall area of the heat transfer surface finned by deforming cutting has shown that sample No 5 has maximum value of the performance criteria when the maximum height of a fin is 0.008 m and the minimum pitch of a fin is 0.0025 m over the investigated sample range. Thus, when the sizes of an oil air cooling device are maintained by using the amended heat transfer section of sample No 5, the amount of removed heat can be increased or the mass and dimensions of the device can be decreased while maintaining thermal power and, as a result, the power consumption for pumping can be decreased and the thermal-hydraulic performance of the device as a whole can be increased.

The article presents the results of experimental studies of the local hydrodynamics of the coolant flow in the mixed core of the VVER reactor, consisting of the TVSA-T and TVSA-T mod.2 fuel assemblies. Modeling of the flow of the coolant flow in the fuel rod bundle was carried out on an aerodynamic test stand. The research was carried out on a model of a fragment of a mixed core of a VVER reactor consisting of one TVSA-T segment and two segments of the TVSA-T.mod2. The flow pressure fields were measured with a five-channel pneumometric probe. The flow pressure field was converted to the direction and value of the coolant velocity vector according to the dependencies obtained during calibration. To obtain a detailed data of the flow, a characteristic cross-section area of the model was selected, including the space cross flow between fuel assemblies and four rows of fuel rods of each of the TVSA fuel assemblies. In the framework of this study the analysis of the spatial distribution of the projections of the velocity of the coolant flow was fulfilled that has made it possible to pinpoint regularities that are intrinsic to the coolant flowing around spacing, mixing and combined spacing grates of the TVSA. Also, the values of the transverse flow of the coolant caused by the flow along hydraulically nonidentical grates were determined and their localization in the longitudinal and cross sections of the experimental model was revealed. Besides, the effect of accumulation of hydrodynamic flow disturbances in the longitudinal and cross sections of the model caused by the staggered arrangement of hydraulically non-identical grates was determined. The results of the study of the coolant cross flow between fuel assemblies interaction, i.e. between the adjacent TVSA-T and TVSA-T mod.2 fuel assemblies were adopted for practical use in the JSC of “Afrikantov OKB Mechanical Engineering” for assessing the heat engineering reliability of VVER reactor cores; also, they were included in the database for verification of computational hydrodynamics programs (CFD codes) and for detailed cell-based calculation of the reactor core.

For 300 MWt gas-and-oil-burning power units which durability exceeds the estimated one, when comparing and ranking, it is necessary to take into account not only efficiency indicators (for example, the specific consumption of conventional fuel), but also indicators of reliability and safety. In practice, this is exactly what is being done. However, it is being done just by intuition. An intuitive approach solves this problem, but not always certainly. It would seem that there is a quite fully developed mathematical apparatus for regression and correlation analysis, a set of algorithms and calculation programs. But there is one specific feature that, if it is not taken into account, further increases the risk of an erroneous decision. The fact is that the average monthly data on the technical and economic indicators of power units do not belong to the samples from the general population that correspond to the normal distribution law, the latter being a necessary condition for using such methods. This is a non-random sample from a finite set of multidimensional data. Naturally, the methods of classification of multidimensional data are not simple; they require the development of special calculation programs that recommend solutions for maintenance and repair, load distribution, etc. The article presents only one, but very important issue of the problem, viz. the assessment of the reliability of the assumption about the linear relationship of technical and economic indicators. Its solution will simultaneously demonstrate difficulties in comparing the efficiency of aging power units. It is noted that the known and practically used method for assessing the reliability of the linear regression equation, based on the construction of a “confidence corridor” or “uncertainty band”, does not allow one to answer the main question, viz. whether the relationship of the considered technical and economic indicators corresponds to a linear one. A new method for evaluating this relationship is proposed, based on constructing a fiducial domain of possible regression line implementations. It is shown that for small values of the number of sample implementations, a significant part of independent samples has a correlation coefficient exceeding 0.9.

The process of heating a dewatered object in an infrared solar drying plant (with paraffin on the bottom) with solar energy storage is considered. To solve this problem, it is assumed that the heat capacity of paraffin exceeds the heat capacity of the dehydrated object. Infrared rays fall on the upper layer, and heat exchange takes place due to heat and mass transfer with the surface air located between the metal plate and the object to be dehydrated. The equations of thermal conductivity for a dewatered object are given, its relationship at the phase interface is determined using the equality of temperature and heat flow. For an exposure of overheating with a period of 6.5 h, the time of passage of the phase boundary in accordance with the law of motion of the spreading (hardening), was determined according to the formula of  ξ = α √6,5 h ≅ 12 h.

The optimal thickness of the accumulating paraffin layer was ascertained. On the basis of the theoretical studies, experiments were conducted to study the temperature field of various heataccumulating materials in the laboratory of Tashkent State Technical University. It was found that of all heat-accumulating materials, paraffin has the best heat retention ability when its thickness is of 2–4 cm. The optimal variant of a solar accumulator drying plant with a heat accumulator, viz. paraffin has been designed. In particular, 2–4 cm of paraffin layer with a mass of 50 kg with a corresponding flat surface in terms of specific heat of evaporation is 2400 kJ/kg. The specific melting value of paraffin (150 kJ/kg) allows additional evaporation of 5.8 l of moisture when drying objects. The proposed solar accumulator drying plant can be used for dehydration of medicinal herbs.