Despite the widespread use of single-flue stacks, due to the possibility of increasing the rise of flue gases into the atmosphere due to the close location of individual flues in a common shell and ensuring the high reliability of this shell by isolating it from flue gases, multi-flue stacks are increasingly being used. To minimize their cost, it is necessary to determine such an arrangement of flues, in which the diameter of the stack shell will be minimal.

THE PURPOSE. Consider the main types of multi-flue stacks used in world practice. Obtain an analytical solution for determining the minimum possible diameter of the reinforced concrete shell of a four-flue stack with flues of different diameter.

METHODS. Graphical and analytical methods using computer modeling, as well as the use of computer-aided design systems.

RESULTS. An analytical solution is obtained to determine the minimum possible diameter of the reinforced concrete shell of a four-flue stack with stems of different diameters at given distances between the flues and between the flues and the containment shell as a solution to a system of algebraic and trigonometric equations. The distances between the flues and between the flues and the containment can be set to any. In this paper, a new methodology and calculation program for four-flue stacks has been developed. It is shown that the shell diameter depends on the arrangement of flues of different diameters. In the absence of space restrictions for flues, flues with the largest diameters should be placed opposite each other. The obtained method for determining the shell diameter due to more accurate design and when all specified conditions are met, allows to reduce the cost of the shell by 4–9 % compared to the current method for determining the shell diameter.

THE PURPOSE. To estimate the most effective length of the working blade of the last stage of a powerful wet-steam turbine in terms of obtaining its maximum efficiency and to optimize the parameters of this stage in the design mode. For this stage, perform multi-mode optimization to select the main characteristics of the stage operating with maximum efficiency according to a given model daily load schedule.

METHODS. When solving this problem, the method of calculating the axisymmetric flow of steam in the flow part of the turbine stage as an inviscid single-phase working fluid relative to a stationary guide device and rotating with an angular velocity ω of the impeller used, and the losses energy calculated according to the axisymmetric method of the MPEI.

RESULTS. The article describes the relevance of the topic, discusses the features of the use of the author's software in solving the tasks. The characteristics of the stages with different lengths of the working blades presented and the results of their calculation in the nominal mode are given. A model daily schedule selected for a nuclear power plant turbine operating in the central region of Russia. The results of calculations of variable modes of the last stage of the turbine operating according to this daily schedule presented.

CONCLUSION. The choice of the maximum length of the working blade is limited not only by its strength characteristics, but also by the increase in wave losses in the gratings due to an increase in the optimal available heat drop, or rather the associated increase in supersonic speeds near the meridional contours. So for a high-speed turbine To-1200-6,8/50 the maximum efficiency of the last stage is achieved at a length of 1400 mm, both when the turbine is configured with both three two-flow LPC and four. Selection of the main characteristics of these stages, such as the available heat drop, the degree of reactivity, etc. it should be made taking into account the variable operating modes of the turbine on the basis of the forecast of daily schedules of loads of turbine units. When using a typical daily load schedule, the average internal relative efficiency in the range of operating modes according to this schedule is higher by 0.6 % when choosing a 10% increased available heat drop compared to the optimal one in the design mode.

THE PURPOSE. The purpose of this work was to use the associated paradigm for a correct quantum-chemical description of non-catalytic and catalytic supercritical fluid processes of transesterification of triglycerides with alcohols and hydrolysis of triglycerides and to model a one-stage process for obtaining biodiesel fuel, carried out under supercritical fluid conditions with its subsequent scaling to the commercial level.

METHODS. The Gaussian09 software product was used to describe quantum chemical studies. The process modeling was carried out using the ASPEN Plus® v2006 software product. The behavior of thermodynamic systems at high temperatures and pressures is modeled using "RK ASPEN EOS". For modeling processes carried out at low pressures, mathematical models UNIQUAC and UNIFAC-LL were used. The scaling of the process was carried out in the VMGSim program.

RESULTS. The third part of the review focuses on the quantum-chemical modeling of the transesterification reaction carried out under supercritical fluid conditions. It is shown that taking into account the associative paradigm makes it possible to obtain calculated reaction rate constants that agree in order with the experimental values. And also an analysis was carried out and the results of modeling the process of obtaining biodiesel fuel and scaling it to a commercial level, with a capacity of up to 9000 tons / year, were presented.

CONCLUSION. The conducted analysis showed that biodiesel fuel can be a competitive fuel in our and the world market.

THE PURPOSE. Development and creation of an experimental stand, carrying out a full-scale experiment, verification the numerical model of a NREL S809 airfoil based on its dimensionless characteristics, analyze the flow around the airfoil at different angles of attack.

METHODS. A technique for studying the flow structure around a wind turbine using numerical methods of gas dynamics based on solving the system of Navier-Stokes equations is considered. Mathematical modeling methods were used using the k-ε and SST turbulence model.

RESULTS. In this study, a laboratory stand is designed using CAD systems and created using additive FDM printing technologies An experimental study of the dependence of the rotation speed on the blade angle and the resulting voltage in the electric system, the change in the power factor and efficiency of a wind power plant depending on the wind speed was carried out.

CONCLUSION. The developed wind turbine has a power of 2.6 W at a wind speed of 4 m / s. This invention is recommended for the purpose of teaching methods of design and construction of similar installations. For the developed wind turbine, it is possible to optimize the work using the method of numerical three-dimensional thermogasdynamic modeling, to evaluate the nature of the flow at off-design operating modes, which speeds up the process of creating the final installation and improves its efficiency parameters.

THE PURPOSE The article is devoted to the analysis of the problems that arise during the operation of heating CCGTs of the type CCGT-450 at reduced loads with their participation in the regulation of electrical and thermal loads. The description of the main limitations of the adjustment range of gas turbines, and the maneuverability characteristics of the CCGT, an analysis of some existing technical proposals for expanding the adjustment range is given. It is shown that the application of these proposals, expanding the boundaries of the adjustment range in small quantities, does not solve the problem as a whole. The description and research results of the proposed new technical solutions to expand the adjustment range and maneuverability characteristics of the CCGT - 450 are given.

METHODS. When solving the tasks, the analysis, comparison and generalization of energy characteristics, modeling of modes were carried out.

RESULTS. It is shown that: the use of methods for converting part of the central heating system and the central heating system as a whole of the T-125/150 steam turbine into a low-steam mode together with bypass steam distribution will expand the adjustment range to a level comparable to the adjustment range of condensing power units on gas-fuel oil;. when shutting down the CCGT-450 operating in condensation mode and when operating it in the GTU-CHP mode during periods of night failure of the electrical load, the conversion of the steam turbine to motor mode significantly improves the maneuverability and reliability characteristics of the steam turbine and the CCGT as a whole. conclusion. The use of methods for transferring part of the central heating system and central heating system as a whole and bypass steam distribution expand the adjustment range of the CCGT-450, respectively, by 7.8, 10.1 and 16.0% of the rated power; When the CCGT-450 is operating in condensation mode when the CCGT is stopped and when it is operating in the GTU-CHP mode during periods of night failure of the electric load, the steam turbine is transferred the MR significantly improves the maneuverability and reliability characteristics of the steam turbine by reducing the duration of start-up and loading of the steam turbine by 40 and 14.5 minutes, respectively, reducing starting fuel losses, eliminating temperature fluctuations of steam and metal of the steam intake organs of the central pump and the control stage during start-up;

The PURPOSE of the work is to establish the relationship between the thermodynamic parameters of the Allam cycle and the capacity of the air separation unit. The air separation plant is a consumer of electricity. To solve the problem, a calculation method is developed and functional dependencies are revealed.

METHODS. A research methodology is presented that provides a connection between the thermodynamic parameters of the Allam cycle and its efficiency and fuel consumption, which, in turn, affect the capacity of an air separation plant designed to produce oxygen. The method assumes that the provision of oxygen combustion of methane occurs at their stoichiometric ratio. The method establishes a connection between the thermal efficiency of the cycle and the parameters of the working fluid. Formulas are presented for determining the consumption of standard fuel for the installation, the efficiency of electricity generation and the electric power of the oxygen preparation plant. When obtaining the final result, the factor of influence of the internal relative efficiency of the CO2 turbine is taken into account.

RESULTS. The article shows that in the implementation of the Allam cycle based on carbon dioxide by burning methane in oxygen, an oxygen production unit plays a significant role. This is an energy-consuming equipment for own needs. Quantitative estimates have been made and it has been shown how the initial parameters of the thermodynamic cycle affect the capacity of the air separation unit, in which oxygen is produced. The article shows that its capacity can be provided at the level of 20% of the capacity of the power unit.

THE PURPOSE. Cellular ceramic materials and composites have found application in many industries: energy, chemical industry, construction, aerospace. Due to their high thermomechanical properties, resistance to high temperatures and low density, cellular ceramic materials are widely used as heat exchangers for heat recovery from exhaust gases of gas turbine engines, combined-cycle plants, industrial furnaces, etc. The purpose of this work is to review modern cellular ceramic materials and composites used in heat engineering and having different structure, properties and chemical composition.

METHODS. We have carried out a broad review of the literature on ceramic cellular materials and composites. We studied both domestic and foreign literature.

RESULTS. The analysis of cellular ceramic materials with a regular (lattices) and random (foam) structure has been carried out. The main factors influencing the properties of ceramic foams and lattices are analyzed. Also, the main methods for the production of ceramic materials were studied, their advantages and disadvantages were revealed. A review of modern composite materials based on a ceramic matrix reinforced with carbon nanotubes, graphene nanoplates, and carbon fibers has been carried out.

CONCLUSION. The properties of ceramic cellular materials, as well as their areas of application, depend on the production methods and the structure of the material. Open-cell foams are used as filters, heat exchangers, while closed-cell foams are used as thermal insulation. Applications for ceramic lattices are limited by the precision, resolution, and size of 3D printing. Thus, the improvement of additive manufacturing technologies will improve the characteristics of ceramic gratings and expand their areas of application.

THE PURPOSE. The study is devoted to the problems of ensuring the smooth start and stop of lifting and transport mechanisms. Standard regulators do not allow you to achieve the desired results with changing indicators, the exact values of which are not always available for measurement. Control signals, in such systems, usually correspond to data from a certain range. The paper proposes to replace the standard controller with a controller based on fuzzy algorithms. The process of modeling a system with different types of controllers allows you to explore systems and identify the most optimal of.

METHODS. To solve the problem, the methods of mathematical modeling in the MatLab Simulink environment were used.

RESULTS. The article considers the possibility of using various kinds of regulators on lifting and transport mechanisms. For the functioning of the fuzzy type controller, a rule base has been developed that forms the process of operation of a real object, with an optimal functioning algorithm. Systems with a PID-type controller, with a neural network-type controller with network training, with the possibility of its adjustment for further use, are implemented, the probability of high processor load is taken into account, on the basis of which a supervisor is proposed. The possibility of using ANFIS networks for the implementation of regulators is considered.

CONCLUSION. The use of different types of controllers operating on the principle of neural network technologies makes it possible to achieve optimal performance in the control of lifting and turning mechanisms, both from the standpoint of ensuring the stability of movement, and from the standpoint of system reliability. Compared with the PID type controller, the application of the ANFIS network reduced the fluctuation by 2.9 times, and the use of the fuzzy type controller reduced the fluctuation by 0,75 times. The use of a neural controller compared to the use of the ANFIS network gives a decrease in the fluctuation of the speed formation process by about 0.48 times.

Industrial cities in Syria help the state in developing factories and strengthening the main industries, as they provide the right infrastructure for these industries and provide them with advantages that may not be available abroad. The article explores one of these industrial areas in the city of Adra-Syria.

PURPUSE. Conduct a study of the design power of loads of residential electrical consumers and compare with the experimental power consumption in the city of Adra.

METHODS. Methods for processing statistical data and methods for determining the parameters of loads and graphs of loads of electrical consumers at the facilities of Adra are used.

RESULTS. The data on the parameters of the load curves of the electric consumers of the objects of Adra were determined: The average value of the total load power (Saver), the maximum value of the total load power (Smax), the effective value (S_effective), the standard deviation of the total load power (σ_Sng), the value of the load variation (γ_Sng). The data of the load schedule fill factor, the correlation coefficient (R_kj) was calculated and analyzed, and the values of the statistical indicators of the total schedules (S_tot) of the electrical consumers of the Kabun-1 substation in Adra, the statistical data of the total apparent power of the electrical consumers of the transformers of the 33/11 kV substation were obtained. "Kabun-1", the values of correlation coefficients of loads of industrial electrical consumers, the values of the total power of the load of electrical consumers of the new sector of Adra.

CONCLUSION. As a result of the studies carried out, the possibility of effective implementation of measures to regulate the maximum total power of the loads of the main electrical consumers in the city of Adra has been shown.

THE PURPOSE. To evaluate the influence of the exhaust manifold design on gas dynamics and heat transfer of stationary, turbulent gas flows in the cylinder and the exhaust system of a reciprocating internal combustion engine for different boundary conditions based on physical and mathematical modeling.

METHODS. The study of gas dynamics and heat transfer of flows was carried out using the CFD approach in specialized Russian-made software. The simulation was performed for a pressure drop from 0.15 to 40 kPa (the flow velocity at the outlet of the system was 10-130 m/s). The k-e turbulence model was used for modeling. The computational grid consisted of 610,000 cells. The design change consisted in the use of profiled channels with cross sections in the form of a circle (diameter 30 mm), a square (side 30 mm) and a triangle (side 52 mm).

RESULTS. The article describes the mathematical model, the studied geometry of the exhaust system and the analysis of the obtained data. The velocity field, isolines of equal velocities, and tangential velocity vectors were chosen as the gas-dynamic characteristics of the flow. The gas dynamics in the longitudinal section of the exhaust system and the valve, as well as the visualization of the flow structure in 4 control sections along the length of the exhaust system, were analyzed. The heat transfer coefficient in the exhaust system was used to evaluate the heat transfer characteristics of the flow. Qualitative and quantitative differences in gas dynamics and heat transfer processes are shown.

CONCLUSION. It has been established that there are common gas-dynamic effects during the flow of gas in different elements of the exhaust system. The evolution of the flow structure along the length of the exhaust system is shown based on the change in the velocity field, isolines of equal velocities, and tangential velocity vectors. The vortex structures formed in the valve assembly and the corners of the profiled channels are revealed. It has been established that the use of profiled channels in the exhaust system leads to a decrease in the heat transfer coefficient by 5 to 12%.

THE PURPOSE. The features of the rheological behavior of composite fuel oil suspensions depending on the shear rate, temperature and composition of the composite fuel are considered.

METHODS. Suspensions with a coal content of 30, 40 and 50% (by weight) were prepared. The mixing time varied from 1 to 10 minutes. The samples of fuel oil were examined using a Rheomat RM 100 rotary viscometer to determine the values of dynamic viscosity at different shear rates and temperature.

RESULTS. The results of experimental studies of the dynamic viscosity of fuel oil as a function of the shear rate and temperature are obtained. The best values of coal dust content in fuel oil suspensions for fuel transportation have been determined.

CONCLUSION. The obtained research results can be used by both energy companies and transport companies to determine the technological viscosity indicators of composite suspension fuels used as boiler fuel and fuel for marine engines.

THE PURPOSE of the article is to discuss an updated survey of the technical condition of porcelain high-voltage insulators of the type IOS 110/400, which had defects with partial discharge intensities above 4 nC, at Tatenergo substations. The experiments were carried out with simultaneous use of electromagnetic and acoustic research methods.

During the analysis of the RESULTS obtained, the influence of the fields of previous powerful partial discharges on the technical condition of high-voltage insulators was established. The physical features of detecting powerful partial discharges by electromagnetic and acoustic methods have been studied. The conducted studies allow us to draw the following.

CONCLUSIONS: the previous partial discharges can create additional long-lived electric fields on the dielectric surfaces of defects that exceed the field of the applied operating voltage in intensity; the necessity of using both physical methods simultaneously in the examination of high-voltage insulators in operation is shown.

THE PURPOSE. Consider the indicators of the operation mode of the Kuibyshev reservoir over the past 15 years, affecting the state of the fish stock; identify the main trends in changes in water volumes in the reservoir due to climate change, the features of the level regime for the ecological solution of the problem of preserving aquatic biological resources.

METHODS. A comparative analysis of our own research and literature data on the hydrological characteristics of the Kuibyshev reservoir, the temperature regime of the region and the state of the ichthyofauna was carried out. In this work, to analyze the current state of the hydrological regime, data provided by the Verkhniy Byef gauging station of the branch of JSC RusHydro - Zhigulevskaya HPP and the State Committee of the Republic of Tatarstan for Biological Resources were used.

RESULTS. It is shown that the average water level in the Kuibyshev reservoir for the last period ranged from 50.34 to 52.31 m at NHL - 53.00 m BS, DVL - 45.5 m. Based on the totality of characteristics in terms of average water levels and inflows, 2010, 2011, 2021 can be attributed to low-water years, 2007-2009, 2012-2020 to years with average water content, and there were no high-water years during this period.

The analysis of the dynamics of changes in the maximum and minimum water levels was carried out and changes were identified: the minimum recorded water level (48.16 m) was noted in January (2011), at the end of the 20th century, the minimum levels were recorded in March - April and they were lower by 1-1, 5 m in summer drawdown and 2.5 - 3.5 m in winter, the level rise occurs in April, while earlier it was in May. The duration of the high-water period (about 53 m) increased to 4 months. The minimum volume in the reservoir was recorded in the winter period of 2010-2011 - 36.14 km3, the maximum volume is 57.66 km3 in the winter period of 2019-2020. Maximum water discharges are carried out mainly in the second half of April and early May. Minimum discharges are carried out in different periods.

It is shown that the number of days with an air temperature above 15°C, which characterizes the fishery zone, varies in different years of the last period from 71 days (2017) to 133 days (2020).

CONCLUSION. A relative increase in temperature was noted as the most important environmental factor for the development of aquatic bioresources; currently, the process of accelerating eutrophication of shallow areas of the Kuibyshev reservoir is observed. The regular death of fish in different parts of the reservoir, combined with factors such as low water levels and high temperatures, creates the preconditions for “local catastrophes” at the level of ichthyocenoses, the area of “local catastrophes” is expanding due to climate change. The mortality of fish is a mechanism for the release of the ecosystem from excess organic matter, and the mortality of a small particle indirectly indicates a high abundance of low-value and weedy fish, the number of which must be reduced.