Факультет технічних систем і енергоефективних технологій (ТеСЕТ)
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Item Vapor Overproduction Condition Monitoring in a Liquid–Vapor Ejector(MDPI, 2022) Шарапов, Сергій Олегович; Sharapov, Serhii Olehovych; Mižáková, Ja.; Гусєв, Данило Максимович; Husiev, Danylo Maksymovych; Панченко, Віталій Олександрович; Panchenko, Vitalii Oleksandrovych; Іванов, Віталій Олександрович; Ivanov, Vitalii Oleksandrovych; Павленко, Іван Володимирович; Pavlenko, Ivan Volodymyrovych; Židek, K.We consider the influence of vapor content in the mixed flow leaving a liquid-vapor ejector on the energy efficiency of a vacuum unit. As shown by numerical studies of liquid-vapor ejectors, this issue is important as vapor overproduction, which accompanies the process of secondary flow ejection, directly impacts the efficiency of the working process of both the liquid-vapor ejector and the vacuum unit as a whole. The greater the degree of vapor overproduction, the greater the load on the vapor phase of the separator, which is part of the vacuum unit. In addition, the liquid phase must be returned to the cycle to ensure the constancy of the mass flow rate of the working fluid of the primary flow. Our numerical study results revealed the rational value of the degree of vapor overproduction at which the efficiency of the liquid–vapor ejector was maximized, and the amount of additional working fluid that needed to enter the cycle of the vacuum unit was minimal. Experimental condition monitoring studies on the liquid–vapor ejector were carried out on plane-parallel transparent models with different flow path geometries. Through experimental studies, we confirmed and adjusted the values of the achievable efficiency of the working process of a liquid–vapor ejector, depending on the degree of vapor overproduction. Using a comparative analysis of liquid–vapor ejectors with different flow path geometries, differences were revealed in their working processes, which consisted of the degree of completion of the mixing of the working media of primary and secondary flows. To determine the feasibility of using liquid–vapor ejectors with different flow path geometries, exergy analysis was performed, resulting in achievable efficiency indicators.Item Design of a shelf pneumatic classifier for separating a polydisperse mixture of granulated superphosphate(РС ТЕСHNOLOGY СЕNTЕR, 2022) Юхименко, Микола Петрович; Yukhymenko, Mykola Petrovych; Острога, Руслан Олексійович; Ostroha, Ruslan Oleksiiovych; Bocko, J.The object of this study is a polydisperse mixture of granular superphosphate. It is emphasized that existing technologies of granulation and processing of granules lead to the formation of dusty fractions of small particles. The content of small fractions in the finished product should be minimal and, in connection with this problem, the task is to remove small particles from the mixture. The purpose of the current experimental study is to classify a polydisperse mixture of granular superphosphate in a pneumatic classifier. The device includes an inclined perforated shelf with an unloading space between its end and the wall of the apparatus. It has been experimentally revealed that the maximum efficiency of extraction into the entrainment of small particles is achieved with a width of the discharge space equal to 0.5 of the length of the cross-sectional side of the apparatus; the degree of perforation of the shelf is 5 %; the angle of inclination of the shelf is 25–30°; the speed of the gas flow in the free section of the apparatus is 3.7 m/s. It is shown that the degree of extraction into the entrainment of a small fraction less than 1 mm in size reaches 70–75 %, the content of the small fraction in the carry-over is 96–98 %, and the large fraction is less than 5 %. By processing experimental data, an empirical equation was built that makes it possible to determine the concentration of particles in the gas stream for individual fractions of the material. It is shown that due to the implementation of an active aerodynamic weighing mode, the shelf pneumatic classifier works at specific loads for air flow rate less than the typical designs of fluidized bed separators. It is noted that the effective operation of the shelf pneumatic classifier in the production of granular mineral fertilizers is ensured at a productivity of no more than 10–12 t/h. With greater productivity, there is a need to install several devices in the technological line.Item An Increase in the Energy Efficiency of R744 Heat-Using Thermotransformers(MDPI, 2023) Арсеньєв, В`ячеслав Михайлович; Arseniev, Viacheslav Mykhailovych; Piteľ, J.; Король, Олександр Сергійович; Korol, Oleksandr Serhiiovych; Шарапов, Сергій Олегович; Sharapov, Serhii Olehovych; Mižáková, J.; Павленко, Іван Володимирович; Pavlenko, Ivan Volodymyrovych; Іванов, Віталій Олександрович; Ivanov, Vitalii OleksandrovychThis article deals with improving waste heat transformation in heat-using thermotransformers. Based on the directives of the European Commission on refrigeration equipment requirements, the possibility of using carbon dioxide (R744) in heat-using thermotransformers was evaluated. The possibility of the effective use of heat-using thermotransformers operating within the Chistyakov–Plotnikov cycle in the heat pump mode was assessed. As a result, a comparative analysis was performed with existing modern plants for combined cycles with an expander, for the expansion of CO2 in saturated steam, a suction gas heat exchanger (SGHE), and a compressor–expander unit. The design schemes with a throttling device and an SGHE were selected for a comparative analysis. As a result, calculation models for evaluating the operating parameters for the initial and proposed design schemes were developed. These models allow for evaluating thermodynamic and mode parameters for heat-reducing thermotransformers. They also allow for ensuring energy efficiency indicators and conversion factors for each cycle. Overall, the dependencies for the cycle conversion ratio for the pressure increase stage in the compressor were obtained for various under-recovery rates. Moreover, the cycle conversion ratios for the proposed design schemes were obtained depending on the discharge pressure of the first compressor. The proposed design schemes allow for increasing the energy efficiency of heat-using thermotransformers by an average of 23%, depending on the suction pressure in the compressor.Item Experimental Studies and Condition Monitoring of Auxiliary Processes in the Production of Al2O3 by Sol–Gel Technology(MDPI, 2022) Склабінський, Всеволод Іванович; Склабинский, Всеволод Иванович; Sklabinskyi, Vsevolod Ivanovych; Ляпощенко, Олександр Олександрович; Ляпощенко, Александр Александрович; Liaposhchenko, Oleksandr Oleksandrovych; Piteľ, J.; Павленко, Іван Володимирович; Павленко, Иван Владимирович; Pavlenko, Ivan Volodymyrovych; Скиданенко, Максим Сергійович; Скиданенко, Максим Сергеевич; Skydanenko, Maksym Serhiiovych; Острога, Руслан Олексійович; Острога, Руслан Алексеевич; Ostroha, Ruslan Oleksiiovych; Юхименко, Микола Петрович; Юхименко, Николай Петрович; Yukhymenko, Mykola Petrovych; Simeiko, K.; Demianenko, M.; Volf, M.; Starynskyi, O.; Юрченко, Олександр Юрійович; Юрченко, Александр Юрьевич; Yurchenko, Oleksandr Yuriiovych; Мандрика, О.Powders and granules of heavy metal oxides produced through condition monitoring are in high demand as intermediate products for obtaining fine-grained ceramics for a wide range of applications, i.e., nuclear fuel and fuel elements for nuclear power plants. Sol–gel technology to produce nuclear fuel (UO2), as well as catalysts (ThO2) for organic synthesis in the form of granules from pressed microspheres, is a promising method to obtain powders and granules of heavy metal oxides (fine-graded ceramics). Al2O3 was selected as the model analog at the stages of obtaining a solution of heavy metal and sol, the formation and gelation of droplets, and the preparation of gel spheres and their further washing and drying, as well as recovery and firing of particles. In the study, the main parameters were substantiated, e.g., the diameter and angle of inclination of the axis for the holes in the perforated shell, the multiplicity of sol circulation before the holes, the coefficients of liquid (sol) flow rate, the oscillation frequency of the disperser, and the concentration of surfactant and acid in sol. All of these parameters affect the characteristics of the granules that are obtained by sol–gel technology. Moreover, recommendations to increase productivity and the energy efficiency of production were also given. In particular, it was found that oscillation frequency in a range of 70–80 Hz leads to a granulometric composition of the obtained granules of 2.0–2.2 mm. A hole of 0.85 mm and a frequency of 100 Hz slightly change this range to 1.2–2.0 mm, while maintaining monodispersity.Item Flow Modeling in a Vortex Chamber of a Liquid–Steam Jet Apparatus(MDPI, 2022) Мерзляков, Юрій Сергійович; Мерзляков, Юрий Сергеевич; Merzliakov, Yurii Serhiiovych; Павленко, Іван Володимирович; Павленко, Иван Владимирович; Pavlenko, Ivan Volodymyrovych; Ochowiak, M.; Іванов, Віталій Олександрович; Иванов, Виталий Александрович; Ivanov, Vitalii Oleksandrovych; Agarwal, P.The article investigated the flow of boiling streams through a nozzle with an oblique cut. Due to this flow organization, deviation from the nozzle axis at the vortex chamber inlet occurred. The study of flow modeling in the inlet section was carried out. The flow design and the calculation scheme of the vortex liquid–steam jet apparatus were proposed. Analytical expressions between the main operating parameters were obtained according to the developed mathematical model. A recommended oblique-cut angle for the active-flow nozzle was evaluated considering the transition through the first critical section based on the tangential velocity flow model. Validation of the mathematical model in the inlet section of the vortex chamber was provided based on the comparison with available experimental data. Flow visualization in the inlet section of the vortex chamber was obtained. The assumption of uneven flow distribution was confirmed experimentally. Overall, the boiling liquid flow was implemented in the active flow nozzle. The obtained scientific and practical results help to determine geometric parameters and physical characteristics of the vortex-type liquid–steam jet apparatus at the design stage. The obtained results were implemented to modernize vacuum units based on vortex type liquid–steam jet apparatuses.Item Modeling of Polymer Composite Materials Chaotically Reinforced with Spherical and Cylindrical Inclusions(MDPI, 2022) Берладір, Христина Володимирівна; Берладир, Кристина Владимировна; Berladir, Khrystyna Volodymyrivna; Жигилій, Дмитро Олексійович; Жигилий, Дмитрий Алексеевич; Zhyhylii, Dmytro Oleksiiovych; Гапонова, Оксана Петрівна; Гапонова, Оксана Петровна; Haponova, Oksana Petrivna; Krmela, J.; Krmelova, V.; Артюхов, Артем Євгенович; Артюхов, Артем Евгеньевич; Artiukhov, Artem YevhenovychThe technical and economic efficiency of new PCMs depends on the ability to predict their performance. The problem of predicting the properties of PCMs can be solved by computer simulation by the finite element method. In this work, an experimental determination of the physical and mechanical properties of PTFE PCMs depending on the concentration of fibrous and dispersed filler was carried out. A finite element model in ANSYS APDL was built to simulate the strength and load-bearing capacity of the material with the analysis of damage accumulation. Verification of the developed computer model to predict the mechanical properties of composite materials was performed by comparing the results obtained during field and model experiments. It was found that the finite element model predicts the strength of chaotically reinforced spherical inclusions of composite materials. This is due to the smoothness of the filler surfaces and the lack of filler dissection in the model. Instead, the prediction of the strength of a finite element model of chaotically reinforced cylindrical inclusions of composite materials requires additional analysis. The matrix and the fibrous filler obviously have stress concentrators and are both subject to the difficulties of creating a reliable structural model.Item Modeling and Optimization of Properties of the Environmentally Clean Molds Based on Oligofurfuryloxysiloxanes for the Production the Metal Castings(MDPI, 2022) Ponomarenko, O.; Yevtushenko, N.; Берладір, Христина Володимирівна; Берладир, Кристина Владимировна; Berladir, Khrystyna Volodymyrivna; Zapolovskyi, M.; Krmela, J.; Krmelovа, V.; Артюхов, Артем Євгенович; Артюхов, Артем Евгеньевич; Artiukhov, Artem YevhenovychThis article is devoted to modeling, researching and optimizing the main properties of an environmentally clean polymer composition based on oligofurfuryloxysiloxanes (OFOS), which can be used to produce casting molds and cores in the production of castings from ferrous and nonferrous metals. Polymer compositions were examined for strength, survivability, gas permeability, moisture, crumbliness, fire resistance, knockout, and stickability. It has been established that the increase in the strength of the polymer composition over time obeys an exponential law. Mathematical equations were derived for all the exponential curves. The indications of compressive strength of the polymer composition with OFOS with all the acid catalysts used were, on average, as follows: after 1 h—1.3–1.54 MPa; after 3 h—2.5–2.9 MPa; after 24 h—4.9–6.1 MPa, which meets the requirements for casting molds before pouring with metal. The use of polymer compositions with OFOS ensures environmental safety of the technological process, due to the lack of emission of toxic substances, both in the “cold” stage of the process and during casting with molten metal, cooling, knocking out, and disposal of polymer compositions. This makes it possible to save energy resources, and thereby reduce the total cost of the entire technological process and castings.Item Impact of Nitrocarburizing on Hardening of Reciprocating Compressor’s Valves(MDPI, 2022) Берладір, Христина Володимирівна; Берладир, Кристина Владимировна; Berladir, Khrystyna Volodymyrivna; Hatala, M.; Говорун, Тетяна Павлівна; Говорун, Татьяна Павловна; Hovorun, Tetiana Pavlivna; Павленко, Іван Володимирович; Павленко, Иван Владимирович; Pavlenko, Ivan Volodymyrovych; Іванов, Віталій Олександрович; Иванов, Виталий Александрович; Ivanov, Vitalii Oleksandrovych; Botko, F.; Гусак, Олександр Григорович; Гусак, Александр Григорьевич; Husak, Oleksandr HryhorovychOne of the urgent problems in reciprocating machinery is ensuring the functional properties of direct-flow valves. Coatings of these parts should increase energy efficiency, reduce compressed gas temperature, and increase compressor performance. In this article, the effect of nitrocarburizing in pastes on increasing the performance and resource of such valves was studied. The primary research methods were metallographic and electron-metallographic research of the surface layer structure of steel 60Si2Cr. Comparison with similar characteristics obtained for stainless steel 09Cr15Ni8Al was also performed. As a result, it was determined that nitrocarburizing of carbon spring steel 60Si2Cr leads to a greater depth of the diffusion layer than nitrocarburizing of alloyed chromium-nickel steel 09Cr15Ni8Al. Simultaneously, the diffusion layers of both types of steel are almost the same. Simultaneously, the increase in the endurance limit of 60Si2Cr steel during nitrocarburizing is about 1.3 times compared to untreated material. Finally, the predictive maintenance showed that the evaluated lifetime of nitrocarburized valves increases by 5.7 times compared with untreated valves.Item The Effect of Blade Angle Deviation on Mixed Inflow Turbine Performances(MDPI, 2022) Chelabi, M.A.; Saga, M.; Kuric, I.; Basova, Y.; Dobrotvorskiy, S.; Іванов, Віталій Олександрович; Иванов, Виталий Александрович; Ivanov, Vitalii Oleksandrovych; Павленко, Іван Володимирович; Павленко, Иван Владимирович; Pavlenko, Ivan VolodymyrovychThe choice of blades for mixed turbines is to achieve the required deflection with minimal losses. In addition, it is necessary that the blade functions without a detachment in a wide area outside the nominal operating point of the machine. In the blade profile study, it is required to satisfy the conditions relating to fluid mechanics and those relating to the possibility of realization of construction. The work carried out presents the effect of the blade deviation angle on the geometric blade shape and the performance of the mixed inflow turbine on keeping the same rotor casing in order to improve its performances. It was remarked that the efficiency is proportional to the deviation angle’s increase, but the rotor became heavy. It has been determined that the effect of the blade deviation angle on mixed inflow performances decreases dramatically starting from the angle −20° for a 100% of machine load. It was urged to avoid relying on angles greater than −20 as values for blade deviation angles. The study noted that the maximum obtained in the output work and power is related to the highest the efficiency for a specific optimum design case (−35° of deviation blade angle) due to the increase in the contact surface between the blade and the fluid, but the problem is that the rotor gets a little heavy (4.37% weight gain). Among recommendations, attention was given to the more significant absolute exit kinetic energies, for values of deviation blade angle between -10° and −20°, where an exhaust diffuser is recommended to use to recover a part of it into a greater expansion ratio. These simulation results were obtained using a CFD calculation code-named CFX.15. This code allowed for the resolution of the averaged dynamic equations governing the stationary, compressible, and viscous internal flow.Item Recirculation power in the balance of hydraulic losses of centrifugal pump(National Mining University, 2020) Boiko, V.; Сотник, Микола Іванович; Сотник, Николай Иванович; Sotnyk, Mykola Ivanovych; Москаленко, Владислав Вікторович; Москаленко, Владислав Викторович; Moskalenko, Vladyslav Viktorovych; Черноброва, Анна Костянтинівна; Черноброва, Анна Константиновна; Chernobrova, Anna KostiantynivnaPurpose. Improving the methodology for determining the recirculation power of low and medium specific speed centrifugal pumps in order to determine ways to increase their energy efficiency. Methodology. A numerical simulation based on the physical nature of the phenomena of recirculation power, conducted using the ANSYS CFX software. findings. The dynamics of changes in the integral parameters of the operational process of a centrifugal pump D20001002 at flow rates that deviate from optimal (Qopt) are investigated and presented. Based on the results of the numerical simulation, the values of the theoretical head of the impeller, as well as the head at its outlet, taking into account and excluding recirculation, are determined. Due to the difference in the obtained head values, the value of the power losses for recirculation and their part in the balance of hydraulic losses are determined. Based on the simulation results of the operational process of the centrifugal pump D20001002, it is shown that part of the recirculation losses in the flow rate range (0.7–0.4)·Qopt is 25–30 % of the total hydraulic losses, while in the flow rate range (0.3–0.1)·Qopt it increases to 44 %. originality. Further development of the method for determining the recirculation power which is based on the results of numerical simulation of threedimensional fluid flow in the flowing part of the centrifugal pump, taking into account the circulation vortex processes at the outlet of the impeller. Practical value. Definition of the recirculation power in the power balance of hydraulic losses at the pump design stage. Taking account of the influence of the design parameters of the impeller on the value of recirculation.