Advances in Design, Simulation and Manufacturing V

The solution to the problem of the power turbines vibration reliability at failures arising as a result of resonant frequency hit in the operating range of a rotor considering the randomness of the support rigidity change on the foundation is considered. The study finds a complex machine-building object - the steam turbine housing on the foundation. The subject of the study is the failure as a result of vibration resonance in the operating frequency range. The reason for failures can be various design and technological imperfections. They can be divided into two groups: imperfections resulting from design and creation, and on the other hand - deviations from the design parameters as a result of the long-time operation. A special factor in the occurrence of various imperfections (deviations) is the time over which the probability of trouble-free operation decreases. To solve the problem, the methods of oscillation theory, reliability, and the widely used finite element method are used. Based on experimental data on the accumulation of rigidity imperfections on the foundation, the series of calculations of natural frequencies and forms, which are once again compared with experimental data, is carried out. The obtained results determined the probability of failures in the operating frequency range from the most dangerous resonances.

This paper justifies the primary conditions for the strength, rigidity, and stability of the part’s structural elements (a mechanism). They presented the theoretical and practical part of the conditions for checking the strength of a beam (Rod). Graphically presented the stress \({\sigma }_{n}{, \tau }_{n}\) in height. We investigated the behavior of the rod (beam) model when calculating the tensile-compressive strength. Based on the results obtained, plots of longitudinal forces were constructed. It was found that at each point of the cross-section, internal bonds (forces-N) arise, which are evenly distributed. It should be noted that the constructed plots of tensile forces were carried out based on improved equilibrium equations. In this case, the axial force formed on the first section was determined by the algebraic sum of all forces located only on one side of the section. We investigated the strength conditions that did not exceed the limits of permissible limit norms. We also investigated the main parameters and limits of permissible norms of reference reactions, confirming a reliable test for all three main strength conditions. It should also be noted that the SolidWorks software product performed computer modeling based on strength analysis, which made it possible to design the main structural elements of this part. Also, to study the behavior of the calculated beam model under various influences in terms of static, part stability, natural frequency fluctuations, and external load application.

The floating ballard is one of the main elements of the mooring equipment included in the lock. The reliability of this element largely determines the performance of this complex hydraulic unit and reduces the costs associated with the accident rate of both the lock itself and the ships passing through it. The close relationship between the reliability of the bollard and the magnitude of external forces (acting on its structure) requires a deep analysis of the stress-strain state of both the bollard elements and their connection places. The article deals with studying an actual composite welded structure of a ship’s lock floating bollard under short-term action of loads exceeding the nominal load due to the dynamics of mooring operations and weather conditions.The studies were carried out on the developed 3D model of the device, and the analysis of the stress-strain state of its elements and the places of their conjugation. Some simplifications were applied, and the finite element method was used. A graphical representation of the results of the study made it possible to establish a general picture of the stress-strain state of the bollard elements, as well as to establish the local places of probable damage. Based on the results obtained, appropriate conclusions are drawn that determine possible solutions to the identified problems.

The paper ensures the vibration reliability of the centrifugal pump CPN 600-35 for the water supply of an industrial circuit at nuclear power plants by improving its technical designs. The main aim of the research is to develop an approach for parameter identification of rotor dynamics and analyze the dynamic stability of the rotor movement. For this purpose, the modified design of the centrifugal pump CPN 600-35 was developed. Also, the main parameters of the rotor dynamics model (e.g., equivalent stiffness and discrete mass) were evaluated based on the parametric identification approach. Moreover, the eigenfrequencies and the corresponding mode shapes of free oscillations were obtained based on the finite element method. Finally, the dynamic stability of the rotor movement was studied based on the developed mathematical model of its oscillations considering the circulating and internal friction forces. Finally, based on the Routh-Hurwitz criterion, the stability region of rotor movement in terms of the dimensionless frequency and friction coefficient was analytically obtained.

Crane spans with prestressed girders operate under the same conditions, modes, and load capacities as conventional cranes. The load-carrying capacity of their spans must be provided with high strength and stiffness in two planes - in the main vertical plane and the horizontal plane. However, studies of the stress-strain state of a crane with a prestressed bridge operating in the horizontal plane have not been conducted. A mathematical model of the pre-stressed main beam has been developed in the paper. An analysis of its deformed state from the plane of cargo suspension and under the simultaneous influence of vertical and horizontal forces has been carried out, which allowed establishing. The obtained results can be further used to design bridge-type cranes with prestressed span beams to increase their lifting capacity and extend their service life without disassembly. As well as improving the existing structures and engineering methods of calculation, both at the design stages and under real operating conditions.

The movement of a material particle on the inner surface of an inclined cylinder rotating around its axis with a constant angular velocity is investigated in the article. When a particle hits the surface of a horizontal cylinder, it begins to oscillate in the cross-sectional plane of the cylinder with a certain amplitude in the angular dimension. Its value depends on the incidence point, friction coefficient, and initial absolute velocity. Differential equations of movement in projections on the axis of a fixed coordinate system are compiled. They are solved numerically. Under the appropriate initial conditions, which are determined analytically, the particle in absolute movement can be stationary, being at a point on the cylinder at a certain distance from the lower point in the angular dimension in the direction of the rotation of the cylinder. Some movement cases are described when the angle of inclination of the cylinder's axis to the horizontal plane is greater, equal, or less than the friction angle on the cylinder’s surface. An analytical solution for the last case that describes the particle's movement after stabilization is found. Visualization of the obtained results is made.

The article presents a study of the flow of supersonic flow in the interscapular duct of a nozzle with a rotating aperture at low degrees of opening. Modeling and calculation of the working fluid flow were carried out using the Fluent software package. The construction of computational domains, limited by one interscapular channel, for different degrees of opening of the nozzle diaphragm has been carried out. Grids for computational domains have been built. A numerical study of the flow in the interscapular channel of the C-9013R airfoil lattice at π = 0.3 δ = 0.3 was carried out using the Reynolds Stress turbulence model. A numerical study of the spatial flow in the interscapular channel has been carried out. As a result of the calculations performed, the flow patterns in the interscapular channel and behind it were obtained. The distribution of the kinetic energy loss coefficients along the grating front at various degrees of opening of the diaphragm at the inlet to the nozzle apparatus. The results obtained in this work will develop a method for multi-parameter optimization of cogeneration steam turbines with controlled steam extraction.

At present, it appears that systems of pneumatic units with discrete and analog control, in which the required analog law of motion of the output member is provided with the help of discrete switchgear, offer a promising potential. When developing the schemes of positional hydraulic-pneumatic units, the parameters of the movement of the hydraulic-pneumatic unit are studied, namely: the value of displacement, speed, and acceleration of its output member. To carry out the simulation, a design based on discrete switchgear was taken as the basis for the pneumatic positional unit. Solving the inverse problem, i.e., with the law of motion of the output member of the pneumatic unit (specifying the positioning function) known, we determine the mandatory law of change in the effective areas of the control line and represent each equation of the dynamic model as block diagrams. A mathematical model of the system of pneumatic positional units with program control was developed. It considers the features of the system of pneumatic units and consists of mathematical models of the actuator, a real-time control line model, and a real-time control system. The proposed algorithm for analysis of dynamic characteristics using the MATLAB simulation environment confirms the adequacy of the mathematical models describing the operation of a positional pneumatic unit implemented on discrete pneumatic equipment. The developed algorithm is advisable to analyze the operation of the existing one and for designing new technological equipment.

The paper presents comprehensive research synthesizing inertial and stiffness parameters of two-mass vibratory systems of increased operational efficiency with nonlinear stiffness characteristics. A generalized optimization criterion is proposed considering a wide range of technological and dynamical requirements for implementing energy-efficient vibratory equipment for different technological purposes (screens, crushers, grinders, breakers, mills, vibrating tables, etc.). To simplify the process of synthesizing the optimal piecewise linear stiffness characteristics, two independent coefficients were introduced into the formulas for determining the corresponding stiffness factors. The synthesis was performed based on simultaneous numerical solving of the optimization problem and the simplified system of nonlinear differential equations that did not consider the dynamics of the drive. In the next stage, the generalized system of differential equations of the synthesized vibro-impact system was considered considering the equations describing the operation of the drive. The dynamic analysis of the system was carried out to provide the corresponding characteristics specified during the synthesis process. The study of dynamic stability of the considered system described by the system of nonlinear differential equations of the second order was performed by reducing to the Hill and Mathieu differential equations. The improved design of the vibro-impact machine was implemented in practice and experimentally tested for vibration deposition of metal layers onto the surfaces of various machine parts.

The operation of power hydraulic drives of self-propelled vehicles is accompanied by oscillatory processes associated with the technical imperfection of the actuating elements of the hydraulic drive. In this regard, the issue of stabilizing the dynamic characteristics of hydraulic drives is an urgent problem. As a result of the research, the initial data and conditions have been substantiated, making it possible to simulate the transient processes occurring in the hydraulic drives of self-propelled vehicles. A structural-functional diagram and a mathematical apparatus have been developed to reveal the dynamics of changes in the characteristics of a hydraulic drive of self-propelled equipment, considering the conditions of its operation. Changes in the stability of the dynamic characteristics of hydraulic drives of self-propelled vehicles, under the influence of the design features of orbital hydraulic motors, have been determined. The acceleration time of the hydraulic motor No. 2 is 12% less than that of the hydraulic motor No. 1, while the pressure and torque fluctuations during steady motion are less by 34% and 17%, respectively. Such changes are due to a decrease in the gap between the teeth of the rotors of the hydraulic motor No. 2 and the elimination of fluctuations in the flow area of its distribution system.

This research aims to investigate the transportation of a material particle by a vertically placed auger limited by a cylindrical casing. The surfaces are coaxial. When the auger rotates, the particle moves to the periphery and interacts with the cylindrical casing. The particle simultaneously slides on both surfaces and rises in absolute movement. Its relative motion is sliding along the periphery of the auger. Differential equations of particle movement in projections on a moving coordinate system that rotates with an auger were compiled. Numerical methods have solved the equations, and graphs of kinematic characteristics were built. The limit value of the rising angle for the helical line was found as the periphery of the auger. At such a position, the rise of the particle stops at a given angular velocity of the auger. It was found that the velocity of particle rising is influenced by constructive and technological parameters. In particular, for a given radius of the cylindrical casing, friction coefficients, and the edge angle of the auger, there is a minimum value of the angular velocity of its rotation. Then the particle “sticks” and rotates together with the auger, describing in absolute motion a circle on the inner surface of the cylindrical casing.

Plain bearing systems are widely used in rotor systems due to their efficiency, simplicity, long life, silent operation, low friction and wear, and in many cases, good heat dissipation. Despite the fact that a significant number of research have been published in the field of calculation and design of plain bearings, the proposed mathematical models and methods for calculating the characteristics do not consider the random changes of some geometric and operating parameters of these complex systems. The thickness of the lubricating film, which is one of the main operational parameters, is determined by the corresponding tolerances for the manufacturing of parts and assembly of the machine and a random variable. This work considers the effect of random changes in middle clearance and eccentricity values on pressure distribution based on the Reynolds equation. It is shown that the possible value of hydrodynamic force in such bearing can substantially differ from calculated under the deterministic models.

The work studied the influence of changing the throughput of distribution systems on the output characteristics of planetary hydraulic machines to ensure their stabilization at the design stages. A design scheme a mathematical apparatus have been developed, and the initial data have been substantiated, which make it possible to study the effect of changing the geometric parameters of the distribution system on the pulsation of its flow area. The pulsation coefficients of the distribution system throughput and the rotational speed of the hydraulic motor shaft, the pressure of the working fluid, and the torque on the hydraulic motor shaft have been investigated. The starting conditions for the design of distribution systems are substantiated, which exclude pulsations of the working fluid in planetary hydraulic machines for kinematic schemes 5/4, 7/6, 9/8, 11/10, and 13/12. The angular gap between the distribution windows was taken as 0°, 0°25′30″, and 0°51″. The number of additional unloading windows in the distribution system was taken as 0, 2, 3, and 4.

The solution to the scientific and practical problem of the modernization of the fuel oil heating department was proposed. The modernization provides two main tasks solutions: maximum heat recovery and existing equipment in the new technological scheme. The limitation of the hardware implementation is the clause of two cross-flow heat exchangers of the Compabloc type presence and two spiral heat exchangers with given surfaces of heat transfer areas. The study’s primary goal is to achieve the assigned task of heating fuel oil by using the existing heat exchange equipment and redistributing the flows. In this case, the flow rates, temperatures, and pressure losses indicated in the formulation of the problem are rigidly fixed, but the possibility of installing additional heat exchange equipment is allowed. The original requirement for recuperative heating with the available apparatuses was not feasible. A new scheme of the heating department with an additional spiral heat exchanger installation was proposed to accomplish this task.

The method of metal protection of boiler condensing heat exchange surfaces can be successfully used in stationary and ship boilers, which burn fuel oils containing sulfur. The proposed method includes the operation of coating with a protective film against sulfur corrosion of the boiler heat exchange surface at a wall temperature below the dew point temperature of H₂SO₄ vapor. A passive layer of iron oxides is used as a protective film. It is obtained by passing physicochemical processes of passivation over the entire condensing surface from the beginning of sulfuric acid vapor condensation by pretreatment of exhaust gas flow with ionizing electron beams with a capacity of about 1 Mrad, ozone water-fuel emulsion combustion with a water content of about 30%. The metal surface is under the protection of a very thin passive film, which has a reliable connection with the metal at the level of the crystal structure and eliminates direct contact of the metal with the aggressive environment. The protective film constantly occurs naturally under the condition of creating an equimolar ratio of nitrogen oxides NO₂:NO (50:50)% in front of the condensing surface in the gas flow. The protection provides a significant increase in the boiler's efficiency (by 4 to 6%) when sulfur fuels combustion in their furnaces and deeper exhaust gases heat utilization in internal combustion engines and gas turbines (to 70%).

Today, industrial ways of oil field development need new apparatus and machines with a significant cleaning result and a single ability, impenetrability, and ease of engineering produce and installation. The article represents an explanation of a hydrocyclone unit for handling wastewater from oilfields based on the application of inertial swirling flows. A new type of installation for wastewater treatment from oilfields has been developed. Due to the radial action in the hydrocyclone and the turbulent flows of the water stream, the oil droplets are damaged, they are increased, and the monodispersity of the liquid phase is growing. In systems with similar types of pollution, it is advisable to use multi-product multihydrocyclones and separators-coalescer with plates having holes and curves both for the removal of petroleum products and for the removal of suspended solids with a density higher than the density of water. Local treatment equipment, consisting of an average of four product hydrocyclones and separators with coalescent plates, will organize water purification systems at wells and use purified wastewater for formation pressure maintenance systems.

The article presents the results of an experimental study aimed at obtaining scientifically valid data on the kinetics of absorption of carbon dioxide by a barium sulfide solution and the effect of the design of contact elements (trays) on the mass transfer coefficient in this process. The work was carried out using a laboratory model of the absorber, in which it was possible to install trays of various types. Analysis of literature sources showed that the process of a BaS solution carbonization takes place in two stages, sharply differing in pH. An experimental study of CO₂ absorption kinetics under the conditions of the first stage of the process made it possible to identify the most significant factors influencing its rate. It was also found that the limiting stage of mass transfer is the resistance in the gas phase. The carbonization rate at the second stage is significantly lower than at the first stage and is controlled by the kinetics of the chemical reaction of CO₂ hydration. Mathematical processing of the results of testing models of the cap, sieve, and double-flow trays made it possible to obtain formulas for calculating the mass transfer coefficients for each of them. In the studied range of gas velocities, the mass transfer coefficient on a dual-flow tray was 1.5–2 times lower than on a sieve tray and 2–2.5 times lower than on a cap tray. The data obtained were used in the design of the absorption apparatus.

One of the promising areas for intensifying the mass transfer process is the improvement of separation columns using a stabilized foam mode of interaction of gas-liquid flows, including movable nozzle bodies. A new design of the stabilizer with a sizeable free volume and a spherical movable nozzle was developed. The advantage of the proposed design is the transition to a structured foam mode of operation at relatively low gas speeds and a developed phase contact surface. After experimental studies of the hydrodynamic characteristics of the combined contact element, empirical data on hydrodynamic resistance and experimental indicators of spray attribution for a contact stage with combined contact elements were obtained. As a result of research, it was found that when using foam layer stabilizers, the spraying ratio at the contact stage is reduced, which leads to a more stable operation of the device. An empirical equation for determining the value of the spray attribution is given.

Theoretically substantiated prerequisites for improving the production process of liquid biofuels from technical animal fats (TAF) and fat-containing wastes from food and livestock products, which makes it possible to design reactors for the production of liquid biofuels. A mathematical model for converting coolant and fat-containing waste into diesel biofuel has been developed. The feasibility of its use in the design of batch reactors with mechanical mixers has been proved. Turbulence models and their parameters are determined, which adequately characterize the velocity fields in reactors with turbine stirrers and provide an adequate description of the kinetic energy dissipation rates in different technological zones of reactors for the production of biofuels from TAF and fatty waste. It was found that the change in the distance between the stirrers and their diameters leads to a significant change in the rate of kinetic energy dissipation, which allows to unambiguously determine the place of introduction of alcohol-catalytic solvent and affect the degree of dispersion of reagents. The proposed ratio for determining the power criterion for reactors with two-stage six-bladed turbine stirrers and four baffles. Rational relations between the diameters of stirrers and the distance between them ensure the maximum yield of biofuels from the TAF and fatty waste from the food and processing industries. The technique of designing reactors with mechanical mixers for the production of diesel biofuel has been developed and substantiated.

The research results established possible ways of using pharmacopeial or distilled glycerin in confectionery, microbiological, pharmaceutical, enzymatic, and other processing industries. The analysis of research in dehydration of dispersed materials shows that the technological process of glycerol purification is quite complex. It was established that all physical and mechanical properties of the final product and technical and economic characteristics of the equipment can significantly impact the quality of glycerol dehydration. The mechanical dehydration method of glycerin by giving the working drums planetary motion and additional oscillations in the horizontal plane was substantiated. The value of the pressure arising in the drum of the vibrating-planetary installation was determined. A comparative analysis of the vibrating component’s influence on the pressure was studied depending on the angular velocities of water and drum and the loading degree. Existing schemes of moisture transportation and methods of dehydration of viscous and liquid materials were investigated. The analysis of diffusion, mechanical and thermal mechanisms, and their influence on moisture-binding properties of raw materials and the comparative analysis of driving force and speed of processes were carried out. A brief description of the diffusion mechanism and process of moisture transfer in products was given.

Increasing the reliability and durability of superchargers in pneumatic and hydraulic transport is possible due to vortex chamber jet superchargers. Their efficiency significantly exceeds pumping bulk mediums in pneumatic transport using direct-flow jet ejectors. However, the pumped medium losses in the vortex chamber supercharger drainage channel do not allow it to be widely used in such systems. Based on experimental and numerical studies, the influence of the density of the granular material on the losses in the drainage channel has been determined. Mathematical modeling was done by solving the Reynolds-averaged Navier-Stokes (RANS) equations with the Shear Stress Transport (SST) turbulence model. Rational densities of the medium can be varied by changing the vortex chamber height or swirling the inlet flow using a swirler. The design changes are explained by the kinematic features of the solid particle motion. If the vortex chamber height is small, then the particle does not have time to start rotating near the chamber axis and enters the supercharger drainage channel. The absence of the drainage channel in the design will lead to the outlet pressure decrease. As a result of the research, the granular material losses in the supercharger drainage channel have been reduced by 50%, with a twofold increase in the swirl number.

Research results of the regularities of pulsating turbulent flows distribution generated with the transport elements of a vibrating extractor for solid-liquid systems with a small difference in phase densities in a non-flowing liquid medium are presented. The experimental results in the entire investigated range of hydrodynamic operating modes of the apparatus are summarized by the dependences by which it becomes possible to determine the distance between vibro-mixing devices, the dimensions of the apparatus, the height of the unloading device for removing the meal, to choose the design of the transporting open element of the plate, to optimize and scale the process. The proposed operating parameters of the apparatus make it possible to effectively use the energy of mechanical vibrations to intensify mass transfer and countercurrent phase separation of the working mixture. Mathematical models have been developed that can be used for the scaling and design of vibration extraction equipment. For the industry, a new design of the vibroextractor with a conveying system has been proposed, which ensures effective phase separation under conditions of countercurrent vibroextraction of target components from plant materials.

The scientific work presents the results of improving the technology of making cooked sausages with the addition of wheat fiber with pumpkin pectin. The advantage of improving the technology of sausages was determined, particularly increasing their quality for the consumer and the prospects of using plant additives to improve their nutritional value. This paper explores the possibility of adding the combined plant additive of wheat fiber and pumpkin pectin to minced meat. A rational grinding mode is 3–4 min to fractions of 500–600 μm was established, which ensured the homogeneity of the plant additive and would contribute to its uniform distribution in minced meat in the cooked sausages production. The influence of the plant additive grinding level on the functional properties was presented, which showed that the best results for water-holding, water-binding, and fat-holding capacity are provided by particles of a size of 600 μm. Rational parameters for preliminary preparation of the plant additive for mixing with the minced meat associated with hydration at hydromodule were determined. This stage of the technological process provides the highest water-holding capacity, and the 1:3 ratio of the plant additive to refined oil provides a high fat-holding capacity. The solution to this problem improves the biological value and therapeutic and preventive properties of cooked sausages.

One of the ways to increase the efficiency of a gas turbine is an additional expansion of combustion products below atmospheric pressure in an auxiliary turbine installed after the main (power) turbine, that is, the use of an overexpansion turbine. The power received in the overexpansion turbine is spent on pressing the exhaust gases to atmospheric pressure by the compressor. Excess power can be transferred to mechanical or electrical energy. To cool the gas in the overexpansion circuit, it is promising to use a thermopressor, in which an increase in the total gas pressure occurs due to heat removal from gas. The removal of heat from the gas flow is carried out in the process of dispersed water evaporation, injected into the airflow, which is moving at near sound speed (gas-dynamic cooling). The thermopressor is a compact device. Therefore, using it in the gas turbine overexpansion circuit as a compressor and a cooler is advisable. Gas-dynamic cooling in the overexpansion circuits of a low-power marine gas turbine provides a pressure reduction in the overexpansion turbine by 0.725–0.765·10⁵ Pa with a corresponding increase in the main (power) turbine power by 60 to 100 kW.

The fuel efficiency of marine slow-speed diesel engines with cooling the air at the turbocharger suction by ejector chiller that recovers the waste heat of exhaust gas and scavenge air was analyzed. The application of ejector chiller is caused due to its the simplest design that enables easy it's assembling in free space of engine room and reliable operation in a marine application. An assessment was made of air temperature drops in the air cooler at the inlet to the turbocharger of a marine diesel engine and a reduction in fuel consumption under variable climatic parameters along the Odesa-Yokohama-Odesa route. The application of an ejector chiller provides reducing the engine intake air temperature by about 10 °C with a corresponding decrease of specific fuel consumption by 1.0…1.2 g/(kWh) when using only the heat of exhaust gas. The fuel reduction of the marine diesel engine is increased practically twice when additional heat of scavenging air is used by an ejector chiller (ECh). The corresponding schemes of the systems for cooling the air at the turbocharger suction by ejector chiller are proposed.

The combined refrigeration, heat, and power generation (trigeneration) gained widespread application. The reciprocating combustion gas engines are used as drive engines. They are the most adapted to match the actual refrigeration, heat, and electricity needs and manufactured as cogenerative engine modules equipped with heat exchangers to release the heat of exhaust gas, scavenge gas-air mixture, engine jacket, and lubricant oil cooling water to produce hot water converted to refrigeration for technological, space conditioning and heating duties. The efficiency of recovering the heat released from gas engines in a typical integrated energy plant with an absorption lithium-bromide chiller has been analyzed. Issuing from monitoring data on the parameters of heat utilization circuit, the reserves for utilizing the heat usually not recovered by absorption chiller and removed to the atmosphere by radiator are revealed. The advanced heat recovery system that transforms the heat, typically extracted to the atmosphere, by ejector chiller to generate supplementary refrigeration for gas engine intake air cooling was developed as the simplest and expedient solution for implementation at a typical integrated power plant.

The application of absorption lithium-bromide chillers (ACh) for turbine inlet air cooling (TIC) is very effective in hot climatic conditions due to enlarged ambient air temperature drops and fuel reduction. But in temperate climatic conditions, the efficiency of TIC by ACh of a simple cycle is considerably reduced decreased ambient air temperature drops cause that. The last is limited by a comparatively raised temperature of chilled water of about 7 ℃ that makes it unable to cool ambient air lower than 15 ℃. The application of low boiling refrigerants as a coolant enables deeper turbine inlet air cooling to 10 ℃ and lower. Therefore, the low boiling refrigerants can be used for subsequent cooling air after its pre-cooling in ACh. A refrigerant ejector chiller (ECh) is the most simple in design and cheap and can be applied for subcooling air from 15 ℃ to 10 ℃. Such deep cooling air to 10 ℃ in combined absorption-ejector chiller (AECh) provides about twice the annual fuel reduction in temperate climate compared with conventional TIC to 15 ℃ by ACh. The method to determine rational refrigeration capacity of AECh and distribute it between ACh and ECh that provides practically maximum annual fuel reduction at reduced design refrigeration capacity by about 20% is developed. With this current excessive refrigeration, capacities are used to cover peaked loads.

The Ukrainian power generation industry is a fundamental branch for developing the state economy and keeping its sovereignty. A significant problem is the reasonable use of Earth's power resources today. Ukraine has been trying to resolve this issue, which is proved by the implemented program “Safety, Energy Performance, Competitiveness (the Ukrainian Power Strategy till 2035)”. It provides a shift from the old energy industry model to the new one with a larger competitive space and opportunities to increase energy performance via renewable and alternative power sources. A sensible way to complete this task is waste energy recycling. Turbine-generator sets can decrease pressure and utilize potential energy of gas or steam pressure to produce electricity. It is another economic and technological challenge for Ukraine and the whole world. Simultaneously, that opens new prospects for introducing innovative projects. The article is devoted to studying gas-dynamic processes in jet-reactive turbine (JRT) flow ducts. The research assesses the off-design traction nozzle influence on the JRT circular efficiency. There are detected dependencies between circular efficiency and dimensionless velocity \(\lambda_{Wout.t}\) by certain feed-in nozzle inlet pressure during design (S = 1) and off-design conditions (S > 1). Diagrams of circular efficiency against blade wheel velocity (\(\overline{U}\) = 0…1) are drawn. The research established that the feed-in nozzle inlet pressure rise causes the circular efficiency to fall. The efficiency optimum is defined by the blade wheel velocity for design and non-design circumstances. The highest efficiency is found by design traction nozzle operation (S = 1).

Currently, humanity is beginning to experience difficulties with unlimited energy consumption since there are fewer and fewer opportunities to increase capacity generation. The use of renewable energy sources is an effective method of solving the problem of shortage of energy sources. One way to do this is to develop a wind-solar power plant, called a “hybrid”, which simultaneously uses both wind and solar energy. For such a hybrid power plant, it is suggested to use a new type of medium-speed vertical axial wind power station, with a high utilization coefficient of wind energy and improved strength characteristics. Wind turbine models proposed for vertical axial wind power stations were tested in a wind tunnel. A comparison of the capacity of the specific vertical axial wind power station and the proposed wind turbine confirms the value of the wind utilization coefficient at the level of world samples with an average speed coefficient. The simultaneous working wind power station analysis and solar cells and energy utilization are performed. It is indicated that the feasibility and cost-effectiveness of solar cells should be analyzed in each specific case. Formulas for determining the amount of energy produced by a hybrid power station over a certain period are proposed.