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- ДокументSystem for complex exhaust gas cleaning of internal combustion engine with water-fuel emulsion burning(2019) V. S. KornienkoThe necessity to fulfill all requirements of international organizations in the field of environmental protection, need to reduce heat loss in combustion of organic fuels, increasing economy and reliability of all elements of ship's power plant make it necessary to develop complex technology. The aim of study is to develop system for complex exhaust gas cleaning of internal combustion engine (ICE). For performing tasks in technology of proposed method, providing solutions to problems of improving economic efficiency, improvement of environmental indicators and reliability, it is envisaged 5 stages of technological process. At all stages conditions for appropriate running of physico-chemical processes in the next stage are created. Possibility of solving complex problems in proposed technology is ensured by combustion of water-fuel emulsion (WFE) with specifically recommended value of water content W r = 30%. When WFE is burnt with a water content of 30%, the low-temperature corrosion intensity decreases, which allows to install a condensing heating surfaces in exhaust gas boilers. At these conditions an equimolar ratio of nitrogen oxides NO2:NO in gases is required, which is necessary to activate their absorption properties. When WFE is burnt with water content W r = 30% the metal surface with a temperature below of dew point H2SO4 passivates. Experimental studies performed show that: 1 m2 of condensing surface absorbs 3.4 mg/m3 of NOx and 0.89 mg/m3 of SO2, which makes it possible to decrease the NOx concentration by 1.55 times and SO2 - in 1.5 times. There is a process of precipitation of toxic solid ash and soot particles: from 150...170 mg/m3 (at outlet of ICE when WFE is burnt with W r = 30%) to 70...90 mg/m3 after the condensing surface. Consumption of water with alkaline properties decreases when NOx, SO2, CO2 concentration is reduced in front of scrubbers. Reducing pollution of heating surfaces increases the cleaning period of EGB in 2.5 times. The using of complex system provides efficient exhaust gas cleaning at the level recommended by IMO.
- ДокументМетод розрахунку теплообміну під час конденсації холодоагентів у середині горизонтальних труб у разі стратифікованого режиму течії фаз(2019) В. В. Горін, В. В. Середа, П. О. БарабашУ сучасних конденсаторах систем кондиціонування повітря, теплових насосів, випарниках систем опріснювання морської води і нагрівачах електростанцій процес конденсації пари здійснюється переважно у середині горизонтальних труб і каналів. Процеси теплообміну, що відбуваються у теплообмінниках цього типу, мають суттєвий вплив на загальну енергоефективність таких систем. У даній роботі представлено експериментальні дослідження теплообміну у разі конденсації холодоагентів R22, R406A, R407C у гладкій горизонтальній трубі з внутрішнім діаметром d = 17 мм за наступними режимними параметрами:температура насичення 35 - 40ºC, масова швидкість 10 - 100 кг/кв.м/c, масовий паровміст 0,1 - 0,8, питомий тепловий потік 5 ‑ 50 кВт/кв.м, різниця між температурою конденсації та температурою стінки труби 4 - 14 К. Вимірювання локальних за перерізом труби теплових потоків і коефіцієнтів тепловіддачі проводились за методом «товстої стінки» під час різних режимів конденсації. За результатами досліджень установлено, що у верхній частині труби з підвищенням теплового потоку зростає товщина плівки конденсату, що призводить до зменшення тепловіддачі. У нижній частині труби збільшення теплового потоку підвищує тепловіддачу, що характерно для турбулентної течії рідини в трубі. Отримані результати роботи дозволили покращити метод розрахунку теплообміну у разі конденсації пари, яка ураховує вплив течії конденсату у нижній частині труби на теплообмін. Цей метод із достатньою точністю (похибка ±30%) узагальнює експериментальні дані під час конденсації пари холодоагентів R22, R134a, R123, R125, R32, R410a за умови стратифікованого потоку. Використання цього методу у разі проектування теплообмінних апаратів, які використовують такі типи речовин, підвищить ефективність енергетичних систем.
- ДокументAnalyzing 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. PortnoiThe 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.
- ДокументThe relationship between the surface tension and the saturated vapor pressure of model nanofluids(2019) O. Ya. Khliyeva, D. A. Ivchenko, K. Yu. Khanchych, I. V. Motovoy, V. P. ZheleznyInformation on surface tension is necessary for modeling boiling processes in nanofluids. It was shown that the problem of predicting the surface tension of complex thermodynamic systems, such as nanofluids, remains outstanding. It should be noted that the surface tension of liquids and the saturated vapor pressure are due to a specific intermolecular interaction in the region of spatial heterogeneity of the substance (surface layer). Moreover, the compositions of the surface layer of nanofluid and its liquid phase are not equal. The presence of nanoparticles in the base fluid affects the composition of the surface layer of liquids. However, there are no methods for determining the composition of the surface layer of nanofluids and this fact complicates establishing the dependence of the surface tension on the state parameters of nanofluids. It should be mentioned that the number of possible methodological errors in measurements of the saturated vapor pressure of nanofluids is significantly lower than for the surface tension measurements. Therefore, in the development of models for predicting the surface tension, scientific and practical interest has establishing the relationship between the surface tension and the saturated vapor pressure of nanofluids. In the presented work, we consider the nanofluids of isopropanol/Al2O3 nanoparticles and o-xylene/fullerenes C60. Saturated vapor pressure and surface tension of nanofluids of isopropanol/Al2O3 nanoparticles have been studied in the temperature range 293 – 363 K and concentrations of Al2O3 nanoparticles 0-8.71 g/kg. Measurement of saturated vapor pressure and surface tension of nanofluids of o-xylene/fullerenes C60 have been performed in the temperature range 283 – 348 K and the concentration of C60 0-7.5 g/kg. It is shown that additives of Al2O3 nanoparticles and fullerenes C60 lead to a decrease in the surface tension and increase in the saturated vapor pressure. It is shown that there is a universal dependence between the reduced surface tension and saturated vapor pressure for the researched nanofluids.
- ДокументA 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. ShcherbakThe 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.
- ДокументСтенд для дослідження розширювальних турбомашин малої потужності та агрегатів на їх основі(2019) С. М. Ванєєв, Д. В. Мірошниченко, В. О. Журба, Я. В. ЗнаменщиковВ даний час для вирішення проблем енергозбереження проводяться роботи з дослідження та використання малопотужних розширювальних машин для утилізаційних турбогенераторів. Перспективним є створення турбоагрегатів на базі відносно тихохідних вихрових розширювальних машин, але робіт по їх експериментальним дослідженням відомо мало. У зв'язку з цим необхідно створення матеріально-технічної бази, що включає нові і модернізовані стенди, експериментальні модельні та натурні установки, об'єкти дослідження, виробниче та технологічне обладнання, обчислювальні і програмні комплекси. У статті представлені результати розробки і тестування елементів стенду досліджень турбогенераторів малої потужності для утилізації енергії стиснутих газів. Створено експериментальний стенд, на якому можна проводити дослідження і випробування розширювальних турбомашин і турбогенераторів на їх основі різного конструктивного виконання потужності до 15 кВт, а також демонструвати роботу турбогенератора потенційним замовникам продукції. Прилади та обладнання стенду дозволяють плавно змінювати електричне навантаження і отримувати необхідні параметри і характеристики розширювальних машин і турбогенераторів. У складі стенду створена інформаційно-вимірювальна система, яка забезпечує контроль стану обладнання; здійснює реєстрацію інформації і обробку даних вимірювань з представленням результатів в табличному і графічному вигляді; забезпечує надійне зберігання отриманої інформації тощо. Створено дослідний зразок енергозберігаючого турбогенератора на основі вихрової розширювальної машини. Конструкція турбогенератора дозволяє досліджувати вплив основних геометричних параметрів проточної частини на ефективність вихрової розширювальної турбомашини і генератора в цілому. Результати роботи будуть використані для дослідження розширювальних турбомашин і утилізаційних турбогенераторів на їх основі, що використовують енергію стиснутого газу.
- ДокументUsing the heat of recirculation gases of the ship main engine by an ejector refrigeration machine for intake air cooling(2019) R. Radchenko, D. Konovalov, M. Pyrysunko, M. RadchenkoOne of the promising ways in environmentalizing marine internal combustion engines is the neutralization of harmful substances in exhaust gases through particular gas recirculation (EGR-technology). However, the use of such techniques conflicts with the engine's energy efficiency. In the work presented, the scheme-design solution of the exhaust gas recirculation system with using the heat of recirculation gases by an ejector refrigeration machine for cooling the air at the intake of ship's main engine is proposed. The effect of using the heat of recirculation gases for cooling the air at the intake of the engine is analyzed taking into account the changing climatic conditions for a particular vessel's route line. It is shown that the use of an ejector refrigeration machine reduces the air temperature at the entrance of the main engine by 5-15 ° С, which reduces the specific fuel consumption by 0.5-1.5 g/(kW∙h). This reduces emissions of harmful substances when the engine is running with recirculation of gases, in particular, NOx by 30-35%; SOx by 10-12%.
- ДокументAdvisability use of Arduino controllers in automation of refrigeration devices(2019) А. Forsiuk, О. Pylypenko, A. Golub, Ya. Zasiadko, V. Voznyy, R. GryshchenkoThe 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.
- ДокументAdiabated flowing streams in nozzles: influence of regular characteristics on relaxation steam formation(2019) O. Chekh, S. Sharapov, V. ArsenyevTwo-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%.