The article presents a study of single-row air-cooled heat exchangers consisting of bimetallic rolling aluminum finned tubes with different transverse steps of their installation, equipped with an additional intensifying device - a suction shaft, of various heights. The methodology of processing the obtained experimental data is analyzed and the Nusselt numbers reliance on Grashof numbers are presented. The physical picture of the air flow structure passing through a single-row horizontal finned beam is analyzed. Because of the analysis, it was concluded that the installation of the exhaust shaft above the beam leads to a significant increase in heat transfer by a factor of 2.5-3.0, but the efficiency of heat transfer depends on the height of the extraction shaft and on the back spacing. In such case the mixed convective heat transfer reliance on back spacing is differed from a character of dependence as compared to free convection heat exchange.

In practical methods of emergency operation in systems of tractive electric power supply systems the equivalent models of external network constructed on the basis of tractive substations short circuit (SC) reactances are used. Such modeling can give errors of definitions of SC mode parameters. The origin of errors consists of the fact that the offered estimated formulas are based on method of symmetric components with one asymmetry in three-phase circuit. Tractive network short circuit in case of double-sided supply of inter substation zone creates double asymmetry as it affects directly on two adjacent tractive substations, and in case of external network close coupling there is an interference of asymmetries at each other.

For delimitation of simplified equivalent models applicability authors made comparative calculations of emergency operation by means of models constructed in phase coordinates and using external electric power supply equivalent reactances.

Determination of SC currents in system of 27,5 kV tractive electric power supply of rather simple configuration is carried out in three options: on formulas of "Guide-line on relay protection of tractive electric supply ", on full-function estimated scheme of Fazonord complex considering wires capacity and inductive interferences and on specified analytical formula. The received results show rather small errors at SC power exceeding 1000 MV·A. At small values of SC power error can reach several tens percent and becomes inadmissible.

For increase of efficiency protection of busbar 110-220 kV is proposed to use an algorithms, based on the differential principle, in combination with the method of double entry. Double entry it is method of registration of economic operations accounting, by which every change of the state funds recorded in two accounts, ensuring the overall balance. By providing redundant processing of information about currents measured at the ends of the protected object, and is formed in a special matrix that implements the reliable operation of the differential protection, eliminating its excessive action when damaged the current transformers. 

The article presents the results of numerical simulation of the influence of the characteristic temperature of the torch zone of active burning on concentrations of PAHs, represented by benz(a)pyrene in flue gases of coal-fired boiler BKZ-75-39 FB. The research of the intensity of effect of adiabatic temperature on the distribution of heat exchange in furnace of boiler device. The degree of change of absorption capacity of the combustion environment in terms of the effects of the dimensionless gas temperature at the exit from the zone of active combustion. Estimated concentrations of benzpyrene within the temperature zone (less than 1000 K) dust-coal torch. Based on the obtained results we determined the functional dependence of the content of benz(a)pyrene in exhaust gases of the boiler BKZ-75-39 FB from the dimensionless temperature of the combustion products at the exit of the combustion chamber.

 

The article analyzes the directions of using hydrogen, also as an alternative vehicle fuel, and methods of its preparation and concentration with a detailed description of the technology of catalytic conversion (steam reforming) of natural gas and its instrumentation.

The basic principles of the design and schematics of alternative life support systems, whose operation is based on the implementation of the open absorption cycle with solar regeneration of the absorbent. Such systems allow to ensure the sustainability of the use, reduction of energy losses, possibility of complex life support, which includes heating, hot water supply, cooling and air conditioning for residential and industrial premises. The number of variants of such circuitry quite diverse and determined by the specific conditions of the tasks of cooling media and air-conditioning. All heat and mass transfer devices included in the system, double-circuit, providing non-contact cooling of the coolant. Applied new means to use heat and mass transfer devices with a movable nozzle, providing the ability to operate in extreme conditions (polluted environment, sharp fluctuations in loads), increasing extreme loads, high lateral uniformity (scale of problem simplification), undemanding to the quality of flow distribution.

The scheme of compressed-air power plant with use, during recession of electric loading, the absorption lithium bromide refrigerating machinefor additional cooling of compressed air in an aftercooler in front of the air accumulator is offered. The technical and economic analysis of possible variants of change in structure and duration of operation of the compressor and turbine equipment of compressed-air power plant in connection with additional decrease in temperature of compressed air when using absorption lithium bromide refrigerating machineby 10 – 20 ºС is carried out. The variant of introduction of absorption lithium bromide refrigerating machine in the scheme of compressed-air power plant at which profiles of the compressor and gas turbine don't change and changes the duration of their work, it appears more effective. 

 

In the work, the urgency of increasing the accuracy of determining the values of the harmonic components in electrical signals is substantiated. It is shown that it is necessary to take into account the nonlinear character of the change in the circuit inductance to increase the accuracy of determining the amplitude and / or effective values of the higher harmonic components in the primary circuit. Fast-acting algorithms for the accurate determination of the values of harmonic components are described. Results of full-scale tests using the proposed methods are presented. Comparison of the above algorithms for processing secondary signals is performed.

 

The paper is concerned with the problems of modeling active consumption systems. Active consumption systems were considered in this paper. The implementation of active consumer concept is an important scientific problem, which should be solved with a special tool. A mathematical model of active consumer is presented. It takes into account both economic and energy aspects. The mixed integer linear programming is used to solve the problem of the active consumer demand response. An active consumer demand response problem is investigated by the example of electric power supply. To include different generating capacities, we consider power, heat and cooling supply systems. For example, a gas firing micro-cogeneration unit, absorption refrigerating machine, coal firing micro-cogeneration unit and a heat energy storage were chosen. Also, the research is focused on the control of electricity, heat and cooling generation in order to take account of consumers self-generating facilities. Additionally, consideration is given to the function of active consumer in the intelligent integrated energy system according to the basic principles of its formation. The computational experiment technology based on the developed methodological software and support is presented.

In this article the question of increase of efficiency of the combined cycle plant with single-loop heat-recovery boiler due to the inclusion in the scheme of absorption bromide lithium converter of heat.

Reviewed equations for calculation of heat transfer coefficients from a smooth surface, obtained with the use of models of the turbulent boundary layer Prandtl and Deisler. It is shown that the inclusion of disturbances in the boundary layer (roughness of the walls, ledges, ring rolling) can be performed parametrically by adjusting the dynamic speed, the thickness of a viscous sublayer and boundary layer thickness. The results of calculations of the average values of heat transfer coefficients (in dimensionless form of Nusselt numbers and Stanton) and comparing with k nown experimental data. 

A numerical analysis of the formation of temperature fields as a result of the Joule heat release in a segment of a typical lithium-ion battery has been carried out. Software packages ANSYS Electric and ANSYS Fluent were used. At mathematical modeling of convective and conductive mechanisms of heat transfer and the release of thermal energy during the passage of electric current through the material of the plates of the battery were taken into account. As a result of the numerical simulation, the electrolyte temperatures of the accumulator are established when passing currents close to the maximum permissible. Temperature distributions in the investigated region have been obtained.

 

The long-term trouble-free electricity supply to consumers requires the intellectualization of existing power grids. The one the stages of the creation of smart grid is to equip the overhead power lines with devices for automatically collecting information on ice formation. The article proposes the algorithm for OHLs icing monitoring by means of online video measurement of a phase conductor sag. A variant of the technical implementation of the given device is presented and a conclusion about the expediency of its application is made.  

This paper presents the results of experiments for studying the possibility of using crystalline cobalt chloride for drying of transformer oils. It is shown that the use of crystalline hydrates of cobalt chloride for the drying of transformer oils leads to their complete dehydration. This is due to the interaction between the molecules of cobalt chloride and water. To determine the interaction of cobalt chloride with oil and water, absorption spectra in the visible and near-IR region at room temperature were studied in cuvettes 10 mm thick in the wavelength range λ 300 ÷ 1000 nm. It is shown that, regardless of the amount of cobalt chloride added, the transformer oil spectra do not change and, consequently, the chemical composition of the oil does not change. Thisindicatesthatthe cobalt chloride does not react with the transformer oil and remains in full at the bottom of the container with transformer oil. This method is more economical and less "resource-intensive".

The article presents an overview of the current state of work on the integrated use of hydrocarbon raw materials for energy supply to industrial and domestic consumers, as well as generation of process gas. A thermal scheme of an energy-chemical plant with a combined production of energy carriers (thermal and electric energy) and a process gas containing H₂ and CO is proposed. The software product was registered in the form of a mathematical model of a partial oxidation reactor, which made it possible to estimate the parameters of gas synthesis at an air flow coefficient of α=0,7, a pressure increase of π_k=5, and a specific steam flow rate of 6,5 kg/kg (N₂=35,8 %, H₂O=50,2%, CO₂=5,9%, CO=2,6%, H₂=5,5% and temperature 1570 °C), as well as geometrical dimensions of the apparatus D=1,3 m and L=10,8 m.

 

In the article on the base of the modernized physical chemistry model “the perfect gas” of the assuming the presence in it chemical energy and theory of thermodynamic potentials is produced a study of the isothermal expansion of perfect gas. The examination of this phenomenon is realized both for that reversed and not reversed of the versions of the development of process, including this limiting case as the expansion of perfect gas into the void. In the work, the possibility of investigating the process of expanding the perfect gas with the use of a method of thermodynamic potentials is revealed and substantiated. On the basis of the analysis conducted are obtained the results analogous obtained with a study of the data of processes by traditional method. From other side the application “chemical” and “electrochemical” methods of study made it possible to increase the arsenal of the means of those utilized for the isothermal expansion of perfect gas and to obtain the adequate explanation of the effects of local heating and cooling and number of other phenomena, which occur with conducting of the classical experience of GayLussac.