Холодильна техніка та технологія (Refrigeration engineering and technology)

Постійне посилання на фонд

https://card-file.ontu.edu.ua/handle/123456789/6347

https://reftech.ontu.edu.ua/uk/site/page/journal

Переглянути

Зараз показуємо 1 - 20 з 278

A new approach to increasing the efficiency of the ship main engine air waste heat recovery cooling system
(2019) R. Radchenko, M. Pyrysunko, M. Bogdanov, Yu. Shcherbak
The efficiency of integrated cooling air at the intake of Turbocharger and Scavenge air at the inlet of working cylinders of the main diesel engine of dry-cargo ship by transforming the waste heat into a cold by an Refrigerant Ejector Chiller (ECh) as the most simple in design and reliable in operation and by complex in design but more efficient Absorption Lithium-Bromide Chiller (ACh) was analyzed. A ship power plant of cogeneration type using the relatively low-grade heat of water of a heat supply system with a temperature of about 90 °C, that significantly complicates the problem of its conversion into cold were considered. Because of the insufficiently high efficiency of transformation of the heat of hot water (low coefficient of performance) as compared with steam, the resulting cooling capacity may not be enough for cooling intake air of the turbocharger and scavenge air, that raises the problem of the rational distribution of heat loads between the Turbocharger Intake Air cooling circuit (subsystem) and Scavenge air cooling circuit and the need to use chillers of various types. This takes into account the rational parameters of cooling processes of the scavenge air in the cogeneration high-temperature stage of scavenge air cooler, in the intermediate stage of traditional cooling air with seawater, and in the low-temperature stage for deep cooling of the scavenge air by using a chiller. A new approach is proposed to improve the efficiency of integrated cooling Intake Air of the turbocharger and Scavenge Air at the inlet of the working cylinders of the ship main engine of a transport ship, which consists in comparing the required cooling capacity and the corresponding heat needs during the trade route with the available heat of exhaust gases and scavenge air of the cogeneration power plant, determining the deficit and excess cooling capacity of heat utilizing cooling machines of various types, that allows to identify and realize the reserves of improving the efficiency of cooling intake air of the turbocharger and the scavenge air of the main diesel engine through the joint use of chillers of various types.
A STUDY INTO ICE BUILD-UP AND MELTING ON VERTICAL COOLED PIPES
(2016) Y. Zasiadko, O. Pylypenko, A. Forsiuk, R. Gryshchenko
The use of cold accumulators based on the principle of ice build up on the cooled surfaces during off-peak periods and ice melting during on-peak periods is an effective method of electricity bills reduction. Within comparatively short periods of on-peak demand a noticeable amount of thermal energy related to ice melting is to be released, it becomes clear that not only sizing of ice accumulators based on balance calculations is actual, but also the determination of time periods of ice accumulation becomes critical. This work presents experimental unit for obtaining data on the ice build-up on the vertical cooled pipes and later on to continuously register data on the ice thickness diminishing at the regimes of ice melting when cooling of pipe stops. The data for ice build-up and melting for some regimes have been presented and analyzed. The data form the base for deriving semi-empirical correlations allowing to determine a time intervals necessary to generate of ice layers of a given thickness.
Adiabated flowing streams in nozzles: influence of regular characteristics on relaxation steam formation
(2019) O. Chekh, S. Sharapov, V. Arsenyev
Two-phase nozzles, in which the phase transition process takes place, can work in jet superchargers for various purposes, including jet thermal pumps (steam-water injectors) and thermal compressors. In such schemes of thermal transformers, the ejector performs the function of a preliminary compression stage in order to reduce the load on the compression of the working substance in the main compressor. The use of fluxes of boiling liquid as energy-efficient working fluids is inhibited due to the lack of a reliable description of the mechanism of their flow. Finding the dependence of the steam content on the pressure and temperature at the nozzle exit will make it possible to determine the variant of the initial parameters at which the overproduction of steam will be greatest. It is also worth determining the change in the velocity factor, as well as the change in the thrust of the nozzle in the studied range of parameters, in order to find out whether the pressure at the nozzle outlet is a determining factor when choosing the design parameters of the nozzles. The article proposes to investigate the boiling streams in such nozzles by the method of mathematical modeling using a model that takes into account the relaxation nature of vaporization. The study used a compressible two-phase medium model, a kinetic model of evaporation / condensation. The model also takes into account the dynamic and mechanical equilibrium of the process of evaporation-condensation. The calculations were performed using an Ansys CFX commercial CFD product. The value of the mean square relative error of pressure measurement does not exceed 0,119%. The average discrepancy between the obtained data between the mathematical model and the field experiment does not exceed 3%.
Advisability use of Arduino controllers in automation of refrigeration devices
(2019) А. Forsiuk, О. Pylypenko, A. Golub, Ya. Zasiadko, V. Voznyy, R. Gryshchenko
The advantages and disadvantages of Arduino controllers in relation to refrigeration automation systems are considered. An example of using the Arduino controller for creating an automation and monitoring system for a non-standard laboratory refrigeration unit is presented. Arduino is a computing hardware platform for affordable design, the main components of which are the microcontroller board with input and output elements, as well as the Processing / Wiring programming environment in a programming language similar to C, C ++. Arduino can be used to create standalone interactive objects, connect to the software that is used on your computer. The main advantage of using Arduino-based controllers is the availability of information about the microcontroller card, the specification of the elements, the software. Information is freely accessible and can be used by developers in any field. Microcontroller boards have a special structure, due to which, if necessary, it can be expanded by adding new components to the device. Thus, the presented platform allows to improve or change the operation of the automation system of the refrigeration unit, depending on the requirements of the consumer of the cold. The presented variant of automation of refrigeration systems gives an opportunity to come up with a new approach to the design of refrigeration units. During the development of the automation system, a modular algorithm for controlling and protecting the refrigeration unit was created in all its variants, the necessary peripheral equipment and signal receivers were selected. It is shown that the value ratio - functionality of these devices significantly exceeds the similar indicators of the world's leading manufacturers of refrigeration automation systems.
Analysis of similarity criteria for experimental models and equipment of nuclear plant safety systems
(2020) A. E. Denysova, V. I. Skalozubov, V. M. Spinov, D. V. Spinov, D. S. Pirkovskiy, T. V. Gablaya
A criterial method is proposed for analyzing the adequacy of real pipeline systems with pumps of nuclear power plants and experimental installations. The method is based on an analysis of the identity of the determining criteria for the similarity of hydrodynamic processes in real and experimental conditions. The criteria for similarity of real and experimental conditions and conditions of water hammer for pipeline systems with pumps of nuclear power plants in transient and operating modes are determined. Water hammers in transient regimes are a consequence of aperiodic hydrodynamic instability of the flow; and in operating conditions - a consequence of oscillatory hydrodynamic instability. The determining factor of hydrodynamic oscillatory instability is the inertia of the pressure-supply characteristic of pumps. On the basis of the proposed method, an example of the practical application of the similarity criteria obtained for real active safety systems and an experimental plant A.V. Korolev is presented. It is shown that the necessary conditions for identicality of similarity criteria are not met and extrapolation of the results of known experiments to real conditions of active safety systems of nuclear installations with WWER reactors is not justified.
Analyzing the efficiency of moderate and deep cooling of air at the inlet of gas turbine in various climatic conditions
(2019) A. M. Radchenko, Y. Zongming, B. S. Portnoi
The efficiency of deep cooling air at the inlet of gas turbine unite to the temperature of 10 °С by waste heat recovery combined absorption-ejector chiller was analyzed in climatic conditions at Kharkov site, Ukraine, and Beijing site, China, and compared with the moderate cooling to the temperature of 15°C in traditional absorption lithium-bromide chiller. The refrigerant ejector chiller is chosen as the most simple and reliable in operation chiller. It was used as the low-temperature stage for subcooling the air precooled in absorption lithium-bromide chiller to the temperature about 15 °C. Both waste heat recovery absorption lithium-bromide chiller and ejector chiller use the heat of gas turbine unite exhaust gas to produce a cooling capacity. Air cooling at the inlet of gas turbine unite was investigated for varying climatic conditions during the year. The current values of temperature depression with cooling ambient air to different temperatures of 10 °C and 15 °C and corresponding cooling capacities required were calculated. The comparison of the effect due to gas turbine unite inlet air cooling was performed by annual fuel saving and power production growth. With this the current values of turbine power output increase and specific fuel consumption decrease due to cooling inlet air from current varying ambient temperatures to the temperatures of 10 °C and 15 °C were calculated. It was shown that annual fuel saving and power production growth have increased by 1,8 times for Kharkov (Ukraine) site climatic conditions and by 1,6 times for Beijing (China) site due to deep cooling air to the temperature of 10 °C by absorption-ejector chiller as compared with cooling inlet air to the temperature of 15 °C by absorption lithium-bromide chiller.
ANTICIPATED COSTEFFECTIVE EFFECT FROM APPLICATION OF THE EJECTOR HEAT EXCHANGER FOR CONDENSATION OF LIGHT FRACTION HYDROCARBON ON THE PETROLEUM STORAGE DEPOT
(2016) I. Butovskyi, V. Kogut, N. Zhikhareva, M. Khmelniuk
Loss control of oil products is the one of the relevant paths of saving of the fuel and energy resources play a crucial role in development of economics. Now a great many of different procedures of a choice of means of reduction of oil losses and petrol from evaporation are known. However the one part from them did not allow for value of these means and expenditures for them maintenance, another – did not allow for diversity of implementation of means of reduction of losses, third – uses outdated, now, the criterion. In the conditions of petroleum storage depots, as a rule, usage of ejector systems of trapping of light fraction are more preferential, than other hardware’s of reduction of losses. The positive effect from application of an ejector heat exchanger for preventing of losses of petroleum products are calculate.
Application of the Open Cycle Stirling Engine Driven with Liquid Nitrogen for the Non-Polluting Automobiles
(2018) M.B. Kravchenko
COMPLEX QUALITY CRITERION OF CONTROL OF THE INTELLECTUAL SERVICES PROVISION IN NGN
(2016) N. O. Kniazieva, S. V. Shestopalov
The paper is dedicated to intellectual services provision control quality comparison by the intellectual superstructures with centralized and decentralized control principles in NGN. The necessity of three parties interests consideration, namely: service providers, network equipment suppliers and network users is pointed out. The method of complex quality criterion formation is proposed.
COMPUTER PROGRAM FOR CALCULATION MICROCHANNEL HEAT EXCHANGERS FOR AIR CONDITIONING SYSTEMS
(2016) Olga V. Olshevska
Creating a computer program to calculate microchannel air condensers to reduce design time and carrying out variant calculations. Software packages for thermophysical properties of the working substance and the coolant, the correlation equation for calculating heat transfer, aerodynamics and hydrodynamics, the thermodynamic equations for the irreversible losses and their minimization in the heat exchanger were used in the process of creating. Borland Delphi 7 is used for creating software package.
Cooling System for Primary Low Temperature Processing and Storage of Grains of Small Frachioned
(2018) S. Petushenko
Design of high efficiency centrifugal compressors stages
(2019) M. Kalinkevych, V. Ihnatenko, O. Bolotnikova, O. Obukhov
The modern trend in compressor industry is an extension of the use of multi-shaft centrifugal compressors. Multi-shaft compressors have a number of advantages over single-shaft. The design of such compressors gives opportunity to use an axial inlet for all stages and select the optimum rotational speed for each pair of impellers, which, along with the cooling of the gas after each stage, makes possible to achieve high levels of efficiency. The design of high-efficiency centrifugal compressor stages can be performed on the basis of highly effective stage elements. Such elements are: impellers with spatial blades, vaned and channel diffusers with given velocity distribution. In this paper, impellers with axial-radial blades are considered. The blade profile is determined by the specified pressure distribution along the blade. Such design improves the structure of the gas flow in the interblade channels of the impeller, which leads to an increase in its efficiency. Characteristics of loss coefficients from attack angles for impellers were obtained experimentally. Vaned and channel diffusers, the characteristics of which are given in this article, are designed with the given velocity distribution along the vane. Compared to the classic type of diffuser, such diffusers have lower losses and a wider range of economical operation. For diffusers as well as for impellers, characteristics of loss coefficients from attack angles were obtained. High efficient impellers and diffusers and obtained gas-dynamic characteristics were used in the design of a multi-shaft compressor unit for the production of liquefied natural gas. The initial pressure of the unit is 3bar. The obtained characteristics of loss coefficients from attack angles for the considered impellers and diffusers make it possible to calculate the gas-dynamic characteristics of high-efficient centrifugal compressors stages. The high-efficient centrifugal compressors stages can be designed using high-efficient elements, such as: impeller with spatial blades and vaned diffuser with given velocity distribution.
Effect of Adsorbent Grain Size on the Pressure Swing Adsorption
(2019) M.B. Kravchenko
An analytical solution is obtained for a system of differential equations consisting of the equation for diffusion and absorption of a component in adsorbent grains and the balance equation for this component moving in the adsorbent layer.The technique for calculation of steady-state periodic adsorption processes based on expansion of a concentration signal into Fourier series of eigenfrequencies of this adsorption process is proposed. After decomposition each of the eigenwaves independently of the others is passed through the adsorbent layer, and at the output from this layer all this solutions for individual eigenwaves are summed. The solution to a problem of passing an arbitrary periodic concentration signal through the adsorbent layer is obtained as a result of summing the solutions for individual eigenwaves.The proposed method takes into account nonstationary diffusion processes inside the adsorbent grains. It makes possible to analyze effect of the adsorbent grain sizes on a pressure swing adsorption processes.
EN Analysis of modern approaches to improve the efficiency of blackout accident management at nuclear power plants
(2020) A. Denysova, V. Skalozubov, V. Spinov, D. Spinov, D. Pirkovskiy, T. Gablaya
The paper analyzes the approaches to improve the efficiency of blackout accident management taking into account the lessons of the great accident at Fukushima Daiichi NPP in 2011. It is found that the afterheat removal passive systems by natural circulation through steam generators cannot provide conditions for adequate safety functions to remove heat from the reactor and maintain the required feedwater level in the steam generator during blackout accidents and multiple failures of safety-related systems. The application of alternative approaches using auxiliary feedwater steam generator driven pumps requires additional experiment-calculated operability / reliability qualification for a blackout accident and multiple failures of NPP safety-related systems. However, implementation of alternative SDEFP system requires in-depth qualification for the conditions of blackout accidents. Safety systems of passive heat removal from the steam generator (adequately to active safety electrical systems) cannot ensure safety functions on control of required feedwater level in the steam generator and heat removal from the reactor core during blackout accidents (at least 72 hours) and multifailure accidents. The system of the steam generator driven emergency feedwater pump can be the alternative solution to ensure safety functions on heat removal through the steam generator during blackout accidents. Additional study of efficiency of steam driven pumps at the experimental facilities that meet real-life criteria of hydrodynamic similarity is a necessary condition for implementation of system of the steam driven emergency feedwater pump. Application of an integrated approach to manage blackout accidents is reasonable. At the initial stage of accident with relatively high steam pressure in the steam generator it is required supply of feedwater by the steam driven emergency pump
EN Condition and prospective directions of development of renewable energy in Ukraine
(2023) П.І. Панасюк, А.В. Воронін
The problem of rational use of energy resources, increasing the level of energy efficiency and energy security is a necessary condition for the harmonious economic and social development of Ukraine. Renewable energy is a global trend and one of the most promising energy industries in the world. "Green" energy is able to provide the energy needs of all mankind and therefore requires significant attention. Its environmental friendliness and cost-effectiveness speak for themselves, as a result, today all developed countries are taking a cue from the popularization and development of renewable energy, and Ukraine is no exception. Ukraine has significant potential in the field of renewable energy, as evidenced by the main indicators of capacity, production and consumption. It is worth noting the investment attractiveness of this industry. In the paper has been investigated the role of renewable energy sources in the energy balance of Ukraine.The process of carrying out was accompanied by the use of the following general scientific and special research methods, in particular: analysis, synthesis, comparison during the study of the world experience in the development of renewable energy and the determination of promising directions of development. development of renewable energy sources in Ukraine; comparative and retrospective analysis and abstraction to determine the main trends and features of the development of the renewable energy sector of Ukraine, as well as to assess the investment opportunities of entrepreneurship; mathematical modeling to justify the energy and economic efficiency of bioenergy development in Ukraine; economic and statistical - to assess the state of renewable energy in Ukraine; tabular and graphic - for visual display of statistical material and schematic display of theoretical and practical provisions of the study. The segmentation of renewable energy and the analysis of capacities made it possible to determine the main prospects and directions of investment in the industry, based on the example of world experience, and the role of investments for the development of this industry was determined. The paper was carried out an assessment of the development potential of bioenergy in Ukraine based on agricultural crop waste
EN Development of energy-saving technologies and cooling systems for grain storage of small seed cultures
(2023) Д.Р. Болбас, С.М. Петушенко
In the modern world, refrigeration equipment systems, in particular, continuous refrigeration chain systems, without which food safety cannot be fully ensured, are becoming more and more popular. Special interest in artificial cooling systems in the grain economy of Ukraine, which is one of the country's budget-generating industries. Grain is one of the most important basic human food products, for the cultivation and collection of which large resources are involved. Post-harvest processing and storage is a key link in grain production. According to the Food and Agricultural Organization of the United Nations (FAO), about 20% of harvested grains in the world spoil annually. Reduction of grain losses at all stages of harvesting, transportation, storage and processing and ensuring its preservation is determined by the technology after harvest processing. In the conditions of ever-increasing volumes of grain and high rates of harvesting, the problem of preserving the harvest, more than half of which is harvested in a wet state, is becoming increasingly acute. Freshly harvested wet seed grain is unstable in storage and requires immediate processing. Low-temperature conservation in the places of preparations allows to solve the problem of long-term and high-quality storage of grain products. Small grain varieties due to their small inherent linear size, are most prone to damage during heat drying. Combined compression-absorption water-ammonia refrigerator the machine allows you to abandon the use of mains electrical sources for 7 months of the year. Such a refrigerating machine can be made in a transport autonomous version and solve the task of air conditioning in field conditions. To adapt to field conditions, the absorber is made with two-phase thermosiphons and with air heat removal to the environment
EN Energy efficiency projects deployment for Ukrainian industry. Efficiency assessment method for energy exchange and the ratio of temperature change in heat exchangers
(2020) O. Yakovleva, O. Ostapenko, V. Trandafilov
Energy efficiency projects deployment for Ukraine is one of the challenging task today. Ukrainian industry faces very complex environment for project development as well as its deployment within organization nowadays. UA Policy struggle to keep place on the European market to have possibility not only be a part of global policy but to go forward and to bring benefits for macro and micro economy. Fresh breath by integration energy systems within project management into business model of organization let to move closer to hold under control energy efficiency projects realization and avoid financial risks. Environmental policy and energy policy play crucial role for Ukrainian transformation into European player. Presented proactive plan provides possibilities to deliver the intended economic and environmental benefits of the Ukrainian energy labelling and ecological design directives. These directives are in use or are under development process by increasing the rates of compliance with their energy efficiency requirements. To start from the energy efficiency development process investigation in order to have possibilities to make corrections on the stage of modeling and design can bring benefits and reduce costs for end users. To evaluate the efficiency of heat exchangers, there are over 40 different private integral energy efficiency criteria. Such a number makes the estimation of heat exchangers not always objective and sufficiently definite, which does not allow to algorithmize the task of determining the efficiency of heat exchangers. On the foundation of the system element representation for the heat exchange network, the concepts of energy potential and energy efficiency of energy exchange are proposed. The obtained equations allow us to determine the efficiency of energy exchange not only for an element of the heat exchange network, but also for a complex system as a whole with a minimum of information about the system
EN Energy system efficient performance and energy policy
(2021) O. Yakovleva, O. Ostapenko, V. Trandafilov
The 2020 crisis caused by COVID makes the global economy move forward to a new start. In order to achieve strategic goals, the energy sector and the HVAC&R sector forced by faced problems to energy efficiency projects and technologies development and deployment to get fast return on investment and to manage risks for the secure step forward. To meet strategic packet goals global community should redirect investment into the renewables technologies development to integrate them with the energy efficiency projects in the project design phase. On the study of the solar thermal system due to increasing the outlet temperature of ground source heat exchanger it is possible to observe floating increasing COP (operating mode dependence) for the HP system by 4-6%. For getting the greater angles of the collector, the more of the inbound energy can be accumulated and used per annual year. For that reason, collectors intended for the maintenance of HP system, when installing at a large angle. It can reduce the amount of excess heat in the summer season, while the efficiency of the collectors in winter season falling under a smaller angle optimized. The increasing of the COP is caused by reducing of the electrical input to the heat pump cause higher temperature level gain by solar collector. The use of solar thermal collectors bring possibility to reduce borehole depletion. In own turn it can be used for ground heat exchanger regeneration during heat pump stand by. Ukraine can look for the best practices of the sustainable development goals worldwide and adopt them by modifying for actual complex tasks due to actual regulations and development new ones to motivate industrial players on the national and global levels for driving sectors development along with the sustainable development scenario
EN Numerical modeling of a hydrocyclone in the system of technical water supply under the conditions of the UAE
(2020) S. Surkov, Hussam Ghanem, V. Kravchenko
The article is devoted to solving a practical problem: the choice of equipment for pre-treatment of salt water that feeds the desalination plant. The preliminary stage of desalination is the purification of water from sand particles, which can significantly reduce productivity and even damage the desalination plant, which is situated at the next stage. For pre-treatment, settling tanks, hydrocyclones, sand filters, etc. are used. The main dimensions of hydrocyclones of standard designs are calculated based on well-known recommendations. Modern computer simulation systems allow you to create three-dimensional models of the apparatus being studied, and then calculate the velocity and pressure fields in them. It was necessary to estimate the amount of sand contained in the feed water. To solve this problem, an experimental hydrocyclone was developed and manufactured. The hydrocyclone was numerically simulated and the sand capture coefficient was estimated under various operating conditions. It has been established that an experimental hydrocyclone reliably captures grains of sand 50 microns in size and above. The average daily mass of trapped sand was experimentally determined. Numerical modeling made it possible with reasonable accuracy to estimate the sand capture coefficient by an experimental hydrocyclone. During the tests, the mass of sand entering the pipeline per day was determined. The hydrocyclone reliably captures sand particles of 50 microns or more. At the same time, a significant part of particles less than 50 microns is not captured by the hydrocyclone, which is why a sand filter was chosen for industrial use. In the future, it is advisable to use a serial connection of a hydrocyclone and a sand filter, but such a solution requires additional technical and economic calculation. It is concluded that in the case under consideration, it is advisable to use a sand filter for preliminary water treatment
EN Solar panels work and control system modeling in LabVIEW and LTSpice XVII. Comparison of the perspectives of panels using
(2021) O. Drozd, L. Scherbak
This paper is dedicated to the research of solar energy issues, namely to increase the efficiency of solar panels and to compare the performance of solar panels in different configurations. The author researches and compares the performance of solar panels with and without trackers. The sun is an inexhaustible source of energy that mankind has yet to appreciate. Solar energy is the kinetic energy of radiation (mainly light) generated by thermonuclear reactions in the bowels of the sun. Solar energy is one such alternative, the neglect of which will in the near future lead to catastrophic consequences for humanity. Solar energy is a progressive method of obtaining various types of energy through solar radiation. Solar energy is one of the most promising and dynamic renewable energy sources (RES). Each year, the increase in commissioned capacity is approximately 40-50%. In the last fifteen years alone, the proportion of solar electricity in the world has exceeded the 5% mark. To increase the efficiency of solar panels, designers and engineers are developing new devices and devices, one of which is a solar tracker. A solar tracker is a device that allows you to control the movement of the sun across the sky, as well as move the solar panel to the position where the absorption of sunlight is most effective. After the conducted experiment , calculations an comparison we can see the next results. Without the solar tracker our panel generated maximum power in 2.4 Watt. After the solar tracking system integration, our panel generated almost 20 (19.8) Watt of power! After this comparison we can tell that the generated power increase in 8.25 Watts. We can also admit that the amount of generated power depends on light intensity. But solar panels are the most effective when the solar beam falls perpendicular to solar cell and solar panel is at an angle of 75 – 85 degrees

Переглянути

Перегляд Холодильна техніка та технологія (Refrigeration engineering and technology) за Назва

Результатів на сторінці

Налаштування сортування