Холодильна техніка та технологія (Refrigeration engineering and technology)

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

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

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Зараз показуємо 1 - 20 з 192

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.
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.
Application of the Open Cycle Stirling Engine Driven with Liquid Nitrogen for the Non-Polluting Automobiles
(2018) M.B. Kravchenko
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.
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 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 Thermodynamic analyses of heat exchangers in cryogenic systems
(2023) О.В. Троценко
The problems of thermodynamic analysis associated with the heat exchangers that used in cryogenic technology are discussed. Heat exchangers of high and medium pressure air separation and fluidizing plants operating at different temperature levels were selected for modelling. There are many features according to which the classification of heat exchangers is made. These features include such facts as the number of flows of the working fluid, the relative direction of the flows of working substances, the purpose of the apparatus, and others. These features are also associated with the design of heat exchangers and the software for the design, which contains thermodynamic calculations. The general thermodynamic approach is based on the equation for the values of the thermodynamic efficiency characteristics and the restrictions imposed on them At the exergy method of analysis, the corresponding balance is based on the energy balance equation. On the basis of this balance, the losses from irreversibility of the selected object and its exergy (thermodynamic) efficiency can be directly determined In a heat exchanger, both types of losses exist, but it is not possible to reveal the contribution of each type to total losses using only the exergy balance. This is due to the fact that this balance is drawn up for a closed control surface that reflects a physical object and not logical reasons associated with this object. Meanwhile, the determination of technical losses is an urgent tasks since the change in the thermodynamic parameters that regulate these losses are the basis for increasing the coefficient of the thermodynamic efficiency of the analyzed system A method and an algorithm for calculating the components of losses from irreversibility in these heat exchangers are proposed. The exergy method of thermodynamic analysis was used to calculate the components of these losses for some two-flow heat exchangers. The investigation of the obtained calculation results is presented
EN Thermodynamic analysis of a real marine refrigeration system for cruise ship "Scarlet Lady"
(2022) Л.І. Морозюк, В.В. Соколовська-Єфименко, В.О. Єрін, О.О. Єфименко, А.В. Мошкатюк
This paper presents an energy analysis of the marine refrigeration system as a component of the machinery system of the cruise liner “Scalet Lady”. This type of ship is one of the most complex types from an energy point of view, which is associated with a wide variety of energy consumers. The study uses two methods of thermodynamic analysis of real cycles: the method of cycles and entropy-statistical method. For the analysis, the experimental data on the operating modes of the marine refrigeration system has been used. According to the results of processing the experimental data, a thermodynamic cycle has been formed and an energy calculation of the cycle has been performed using classical methods for two-stage refrigeration machines. With the help of the cycle model, the external irreversibility is determined by successively reducing the energy efficiency of the ideal cycle. The Lorentz cycle has been chosen as an ideal model, taking into account the variable temperatures of heat supply and removal during heat exchange “heat source – phase transformations of the refrigerant R407f”. Along with the evaluation of efficiency, the distribution of losses by the components of the refrigeration system has been established, energy weaknesses that require improvement has been identified, and the most effective ways to reduce energy costs have been outlined. Analytical conclusions have a graphical interpretation of the thermodynamic efficiency assessment for the real refrigeration cycle. It has been established that in the considered real cycle of a marine refrigeration system, the greatest influence on energy efficiency is exerted by external irreversibility in the condenser, in particular, in the overheating zone (25.64% of the total energy consumption of the plant). The effect of irreversibility in the compressor is not fixed
EN Машинне навчання для властивостей холодоагентів
(2021) С.В. Артеменко, В.О. Мазур
Міждисциплінарний характер нових цілей, спрямованих на розробку робочих матеріалів для екологічно чистих технологій вимагає більш динамічного використання інформаційних технологій (ІТ) для забезпечення правильних компромісних рішень у конкурентному середовищі. Машинне навчання (ML) — це частина методологій штучного інтелекту (AI), яка використовує алгоритми, які не є прямим рішенням проблеми, а навчаються за допомогою рішень незліченної кількості подібних проблем. Машинне навчання відкрило новий шлях у дослідженні термодинамічної поведінки нових речовин. Різні обчислювальні інструменти були застосовані для вирішення актуальної проблеми - прогнозування фазової поведінки soft речовин під значними екзогенними впливами. Метою цього дослідження є розробка нової точки зору щодо прогнозування термодинамічних властивостей м'яких речовин за допомогою методології, яка передбачає штучні нейронні мережі (ANN) та глобальну фазову діаграму для забезпечення кореляції між структурою та властивостями. В роботі представлено застосування машинного навчання в інженерній термодинаміці для прогнозування азеотропної поведінки бінарних холодоагентів і визначення коефіцієнта продуктивності (COP) для роботи органічного циклу Ренкіна (ORC). За даними про кипіння та критичні точки. Запропоновано новий підхід до прогнозування утворення азеотропного стану в суміші, який розроблено та представлено. Цей підхід використовує синергію нейронних мереж та методології глобальної фазової діаграми для кореляції азеотропних даних для бінарних сумішей на основі лише критичних властивостей та ацентричного коефіцієнта окремих компонентів у сумішах холодоагентів. Це не вимагає інтенсивних розрахунків. Побудова кореляцій ANN між інформаційними атрибутами робочих рідин та критеріями ефективності циклу Ренкіна звужує область компромісів у просторі конкурентних економічних, екологічних та технологічних критеріїв
ENERGY EFFICIENCY, ENERGY SAVING POTENTIAL AND ENVIRONMENTAL IMPACT RESEARCH OF LPG CARRIER REFRIGERATION SYSTEM
(2017) V. О. Bedrosov, M. G. Khmelniuk, O. Yu. Yakovleva
Nowadays energy efficiency improvement and global warming are issues of current interest because of the natural resources depletion and extreme climate change. Thus, the problem of formation of strict regulations regarding emissions into the air arises. This paper presents the study of cascade refrigeration system for re-condensing of associated petroleum gas during sea transportation for LPG carrier. The structural optimization has been performed. LPG gas carriers with 266 000 m3 ethane capacity require 15 MW cascade refrigeration system for re-condensing if the temperature in the coastal LPG storage is -70°C, and the temperature for transported Ethan is maintained at -75°C. For current storage conditions the required system cooling capacity is only 1,078 MW intended for the heat gain rejection from the environment during Ethane transportation. The replacement of ozone-depleting refrigerant R22 to alternative agents: R407C, R404A, R402A, R717, R290, R1270 was estimated. The results of analysis have shown that the proposed improvements can be used to optimize the LPG carrier cascade refrigeration system
ENERGY EFFICIENT TRANSFORMERS WITH VARIOUS LOAD GRAPHICS FOR THE CONSUMERS OF ELECTRIC POWER
(2016) Yu. Baidak, V. Matukhno, V. Chaikovskiy
The development and implementation of a new economic electrical equipment, in particular, energy-efficient distribution transformers – is a very essential step to reduce electricity losses in 0,4-35kV distribution networks. In a market economy the funds invested into the sector of energetics provide maximum profit to the joint stock company only in the case of the production profitability. In such a situation it is possible to achieve optimal material and energy costs on the transformation of power only under the condition of taking into account such factors as load charts of electricity consumption, the cost of the electrical power losses and maintenance of transformers in the process of exploitation, etc. Existing until today practice of transformers design ignores the actual characteristics of individual customers load charts that results in inefficient use of power transformers capacities during their operation. Non-consideration of the electroconsumer actual operating mode (load curve) in the design period leads to inefficient use of transformer capacity. It is proposed for a tight load schedule to design the transformer for the nearest least normalized power compared to the actual load, providing the possibility of intensification of cooling in case of power consumption increasing.
EVAPORATIVE WATER AND AIR COOLERS FOR SOLAR COOLING SYSTEMS. ANALYSIS AND PERSPECTIVES
(2017) A. Doroshenko, K. Shestopalov, I. Mladionov
The concept of evaporative coolers of gases and fluids on the basis of monoblock multichannel polymeric structures is presented. Different schemes of indirect evaporative coolers, in which the natural cooling limit is the dew point of the ambient air are discussed. In such systems the cooling temperature is lower than the wet bulb temperature of the ambient air. Special attention is paid to the recondensation of water vapor for deep evaporative cooling. It is shown that for the solution of the recondensation problem it is necessary to vary the ratio of the contacting air and water flows, particularly in each stage of the multistage system. Recommendations for the deep cooling process implementation in the evaporative coolers of gases and liquids are given.
FEATURES OF TECHNO-ECONOMIC CALCULATION OF COMMERCIAL COOLING CHAMBERS
(2017) M. Khmelniuk, D. Vazhinskyi, O. Ostapenko
The article touches upon the design and calculation of trade objects refrigerating chambers. The influence of the cost of various groups of components and equipment on the final cost of the camera is analyzed. The influence of such factors as noise, fire safety and location of equipment during operation and installation is described. Recommendations are given on the choice of components in the design.
Influence of Biologically Inert Protective Coating Based on Pectin Substances on PUFA Quality and Shelf-Life of Frozen Fish
(2019) A. Gerasim, S. Patyukov, N. Patyukova
The influence of a biologically inert protective coating on the basis of low-esterified pectin substances (LEPS) on the qualitative indicators of frozen fish and its lipids is studied in this paper: organoleptic, physico-chemical, structural-mechanical and biochemical changes in fish of various methods of freezing during 240 days of cold storage. The limiting periods of storage of a silver carp (Hypophthalmichthys molitrix) of different ways of freezing are established. The prolongation of the shelf life of refrigeration and the higher quality indices of frozen fish with the use of a protective coating based on low-esterified pectin substances is due to the reduction of shrinkage and inhibition of hydrolytic decomposition and oxidative damage of lipids by preventing the contact of the surface of frozen fish with oxygen in the air. In addition, when freezing fish in a calcium chloride solution, the LEPS-based coatings exhibit barrier properties, preventing the diffusion of calcium ions into the muscle tissue of the product. Such a mechanism of influence on the duration of fish storage of various methods of freezing during prolonged cold storage allows to obtain frozen fish with high quality indices and to substantially reduce losses during refrigerated storage.
Investigations of the emission characteristics of a gas turbine combustor with water steam injection
(2019) К.S. Burunsuz, V. V. Kuklinovsky, S. I. Serbin
The article is devoted to investigation of the possibilities of creating highly efficient and competitive Ukrainian gas turbine engines (GTEs), which correspond to modern environmental requirements for new generation energy modules. One of the most important directions of solving this problem is considered, namely, the possibility of realizing a complex thermal circuit of a gas turbine unit (GTU) - the scheme "Aquarius" with the utilization of exhaust gases heat and the injection of ecological and energy water steam into the flowing part of a combustor. The possibilities of reducing emission of harmful components, in particular, of nitrogen oxides, are analyzed, while organizing the process of a 25 MW gas turbine combustor with the supply of water steam to the primary and secondary chamber’s zones. Three-dimensional calculations of the aerodynamic structure of chemically reacting flows in a gas turbine combustor were performed with the help of methods of computational fluid dynamics (CFD). The results of theoretical investigations of gas turbine combustor’s emission characteristics at different ratios of the ecological and energy steam consumptions are presented, their rational values are revealed. The main results of the work can be used at power engineering enterprises for upgrading and modernizing existing and designing models of low-emission combustors of GTE.

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