Том 55 № 1

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  • Документ
    System for complex exhaust gas cleaning of internal combustion engine with water-fuel emulsion burning
    (2019) V. S. Kornienko
    The 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.
  • Документ
    Метод 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. Барабаш
    У  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.
  • Документ
    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.
  • Документ
    The 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. Zhelezny
    Information 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.
  • Документ
    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.