CC BY
1712
TECHNICAL SCIENCE / «ШУУШШУМ-ЛШШаИ» #16И©3), 2021
УДК 620.179.112/075.
Бурлака С.А., Мазур 1.М.
Вгнницький нацюнальний аграрний унгверситет DOI: 10.24412/2520-6990-2021-16103-12-17 ВПЛИВ Б1ОПАЛИВА НА НАДШШСТЬ СИСТЕМИ ЖИВЛЕННЯ ДИЗЕЛЬНОГО ДВИГУНА
Burlaka S.A., Mazur I.M.
Vinnytsia National Agrarian University THE IMPACT OF BIOFUELS ON THE RELIABILITY OF THE DIESEL ENGINE POWER SYSTEM
АнотацЫ.
Ця робота присвячена визначенню надтностг компонент1в паливног системи двигуна внутрШнього згоряння та поргвнянню надшностг елементгв, що працюють на ргзних видах палива. Визначено закон ei-дмови параметра та встановлено вiдповiдно середт ресурси роботи двигуна з використанням альтернативного палива. Проведена порiвняльна оцтка бюдизельного та нафтового палива з точки зору в'язкостi та щiльностi. Як альтернативу, згiдно з рiвнем технiки використовувалося бюпаливо iз соняшниковог олИ, а також метанол.
Abstract.
This work is devoted to determining the reliability of the components of the fuel system of an internal combustion engine and comparing the reliability of elements running on different types offuel. The law ofparameter failure is determined and the average operating resources of the engine using alternative fuel are set accordingly. A comparative assessment of biodiesel and petroleum fuels in terms of viscosity and density. Alternatively, sunflower oil as well as methanol were used according to the prior art.
Ключовi слова. бiопаливо, система живлення, дизельний двигун, форсунка, метанол
Keywords. biofuel, power supply system, diesel engine, injector, methanol
The reduction of world oil reserves, as well as the deterioration of the environmental situation raises the question of the use of alternative fuels for internal combustion engines. One of these fuels is biofuels, the use of which will reduce the consumption of petroleum fuels and reduce the amount of harmful emissions into the atmosphere.
Widespread use of the new fuel is impossible without a comprehensive, comprehensive analysis fuel equipment. And this in turn affects the technical, economic and operational performance of the internal combustion engine.
The diesel engine must provide the following:
1) high injection pressure required for quality fuel spraying,
2) uniform distribution of fuel in the combustion chamber according to its shape in order to form a uniform mixture of fuel and air and efficient the use of air filling the chamber,
3) the exact dosage of the portion of fuel injected to supply it to the combustion chamber, as well as the
possibility of changing the dosage of the portion depending on the engine mode
4) fuel injection in combustion chamber at a certain point of the working process with the required duration according to the most favorable law of injection and under pressure, which provides fine spraying and distribution of fuel in the chamber
5) equal injection conditions for all engine cylinders at different modes of operation, its duration and the moment of the end of giving) sequence of giving according to the order of work of the engine
6) long working capacity without change of adjustments and without wear which influence work engine.
The efficiency of the engine is influenced by many parameters of the fuel used, in particular: density, kg/m3; kinematic viscosity, mm2/s; fractional and chemical composition. The viscosity (V) and density (p) of the fuel have a direct effect on the quality of the spray, the amount of cyclic supply and the completeness of combustion.
Table 1
Possible malfunctions of the diesel engine, fuel equipment and its systems when working on biofuels
Components and fuel characteristics Action Fault
Methyl esters of fatty acids Causes drying, hardening and destruction of rubber products, getting into motor oil Fuel leakage. More frequent oil changes
Free methanol Corrosion of aluminum and zinc Corrosion of fuel equipment. Low flash point in a closed vessel
Free water in the fuel Conversion of methyl esters of vegetable oil into fatty acids. Corrosion. Increasing the electrical conductivity of fuel, the development of microorganisms Filter clogging. Corrosion of fuel equipment
Free glycerin Corrosion of non-ferrous metals. The formation of sediment on the moving parts and paintwork Clogging of filters. Clogging of fuel injector nozzles
Mono- and diglycerides Same as the effect of glycerin
Free fatty acids Electrolyte formation and acceleration of zinc corrosion. Formation of salts of organic acids. Formation of organic compounds Corrosion of fuel equipment. Filter clogging. Sediment deposits on the details
Increasing fuel density Increasing the injection pressure Reducing the life of fuel equipment
High viscosity at low temperatures Tougher operating conditions of the high pressure fuel pump (HPFP). Increased wear of parts Increased wear of PNVT parts. Deterioration of fuel injection . The need for depressant additives
Solid particles Deterioration of fuel lubricity Reducing the life of fuel equipment
Formic and acetic acids Corrosion of all metal parts Corrosion of fuel equipment
High molecular weight organic acids Same as the action of free fatty acids Corrosion of fuel equipment. Filter clogging. Sediment deposition on parts
Polymerization products Precipitation, especially in mixed fuels Filter clogging
Phosphorus Poisoning of neutralizers and catalysts of the engine exhaust system Failure, reduction of environmental safety of engine exhaust gases
We conducted a comparative assessment of the impact of fractional composition (density, viscosity) on the quality of fuel spraying; as well as the chemical composition (presence of active hydrocarbon compounds) on the wear resistance of materials of fuel equipment parts and cylinder-piston group.
As a biofuel was used obtained by technology us-
ing sunflower oil, the values of which met the requirements of the standard and petroleum fuel (DSTU 386899).
The quality of spraying was evaluated on the device KI-562 with the establishment of the diameter of the spray spot at a distance of 100 mm from the nozzle (Fig. 1).
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TECHNICAL SCIENCE / «COyyOMUM-JOUTMaiL» #161103)), 2021
Fig. 1. Spray of petroleum fuel (a) and biofuel (b) a) petroleum fuel with density p20 = 826 kg/m3 and viscosity v = 4.2 mm2/s; b) biodiesel with a density of p20 = 877 kg/m3 and a viscosity of v = 7.2 mm2/s.
The opening angle of the jet and the diameter of the spot on the biofuel is less, respectively, 0.29 <0.36, but its range is greater. This is due to the increased values of viscosity and density.
To assess the fineness of fuel spraying, we use the Sauter formula, which determines the average diameter of a drop of fuel:
^32 _ El
d
0,661
^•[(Pcp-Pa)^Pa]
• a0,193 • y0,147
0,339
0a266 ^ P20
20
where At = A • 2-0a266 - constant value E - experimental coefficient depending on the design of the nozzle and the method of determining the size of the drops, E = 1,445 [3];
0,017
dc - diameter of the nozzle hole of the nozzle, m; - nozzle consumption ratio for modern nozzles, = 0,65;
pcp-average fuel injection pressure, Pa; pa - air pressure in the cylinder before fuel supply, Pa; p20- fuel density, N/m3;
a - surface tension of fuel. N/m. For petroleum fuel a = 27 • 103 N/m, for biofuels a = 31,4 • 103 N/m; v20 - kinematic viscosity of the fuel, m2/s. Determining the diameter of the droplets of biofuel and petroleum fuels by the formula, the dependence of the droplet diameter on the kinematic viscosity is constructed (Fig. 2).
g 0,0165
B
, 0,016 !— <D
<D 0,0155
-•
/ r 2
2 0,015 T3
0,0145
o ,
D0,014
1
0,0135
Kinematic viscosity, mm2/s
c
2
3
4
5
6
7
8
9
Fig. 2. Influence of kinematic viscosity of fuel on droplet diameter: 1 - oil fuel, 2 - biofuel
It follows from the figure that the average diameter of a drop of biofuel is 13% larger than that of oil and, accordingly, are dB = 0.0165 mm, dH = 0.145 mm. The value of surface tension in biofuels is 14% higher than in petroleum.
Thus, during the operation of the injector on such biofuel deteriorates the quality and uniformity of spraying, increases the deposits on the spray, which will slow down the processes of evaporation, oxidation and combustion. This leads to the formation of deposits on the
walls of the combustion chamber and the rapid failure of the engine.
In addition, there are fat deposits in the channels of fuel equipment, polymer deposits on the parts of fuel pumps, coking of the injector holes, hanging needle spray, jamming of the rail of the fuel pumps. All this will reduce the reliability and performance of the diesel engine
Fig. 3. Soap deposits in the fuel system
It is known that the lower heat of combustion of biofuels is 37.5 MJ / kg, against 42.5 MJ / kg of oil, ie 12% less. Therefore, the use of such biofuels will reduce engine power, its efficiency, and the presence of glycerin in it, to the formation of smoke and smoke. and as a consequence on the intensity of wear of parts.
The influence of the chemical composition of biofuels on the change of the surface layers of engine parts is indicated on the metals from which the parts of the fuel equipment and cylinder-piston group are made. The research was based on tribotechnical and chemoto-logical substantiations of the processes that occur in metal friction pairs.
Hydrocarbon-based biofuels contain various types of mercaptans (0.005%), which reduce the wear-resistant properties of materials due to their decomposition with the release of free hydrogen, which can be absorbed on the surface of metals, increasing their fragility. If we accept the working hypothesis that the cause of accelerated wear of friction pairs in the biofuel environment is hydrogen saturation of their surfaces, as mercaptans emit hydrogen during decomposition, then
based on this, it is possible to reveal the mechanism of interaction of structural materials with the environment.
Characteristic of biofuels is the presence of large amounts of methanol, which is aggressive towards metals and rubber products. In methanol, there are eight molecules of hydrogen per three molecules of carbon. When the metal interacts with the environment in the friction nodes, the process of hydrogen evolution and its gradual transition to the surface layer of metal, such as structural steel. At the same time there are some typical chains of physicochemical processes that lead to hydrogen wear. The beginning of these chains is the tride destruction and the emergence of active particles, which are radicals, thermodynamically unstable compounds with double bonds, which easily create new chemical compounds, both among themselves and with the metal surface. These processes can occur due to mechano-dynamic, thermal, catalytic and electrochemical effects of metal during their interaction with friction surfaces (Fig. 3).
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TECHNICAL SCIENCE / «ШУУШШУМ-ЛШШаИ» #16103)), 2021
Fig. 4. Scheme of the effect of methanol on metal catalysts
The effect of biofuels on the change in the surface structure of basic structural ferrous metals can be traced to the example of such materials. This occurs as a result of the reduction of the oxidized aluminum film with carbon, when free hydrogen diffuses to the surface where it increases its amount. Moreover, with increasing residence time in the methyl ether, the thickness of the oxidized film increases. The effect of esters on copper is similar to the effect on aluminum.
Similar processes are observed on the surface of other non-ferrous metals.
Therefore, the use of biofuels with a heavier fractional composition (high viscosity, density) reduces the quality of spraying, mixing, slowing down oxidation processes and, consequently, deterioration of the working process
To improve the quality of biofuel spraying, it is necessary to bring its physical properties closer to the properties of petroleum diesel fuel, or to modernize the fuel injection system.
Fuel based on spray oils with the addition of methyl ether causes the destruction of the surface layers of various materials:
• non-ferrous metals (aluminum, copper), and their alloys are highly exposed to methyl esters;
• of ferrous metals, the most sensitive to methyl esters are cast irons with a ferritic metal base,
• the presence of chromium in steel in the range of 1-3%, which is a catalyst, increases the sensitivity of such steels to methyl esters. Thus, in order to issue recommendations on the impact of biofuels, the operation of the internal combustion engine requires full-length resource tests.
Conclusions
Engine operation on a mixture of vegetable oil and petroleum fuel will create a number of problems: low evaporation, incomplete combustion, coking of spray nozzles, increased soot formation and loss of mobility of the piston rings, faster deterioration of oil quality due
to its polymerization.
The use of biofuel with high viscosity will reduce the efficiency and power of the engine due to incomplete combustion and increase the smoke of the exhaust gases.
Due to the increased aggressiveness of such fuel, it is necessary to replace fuel hoses and gaskets with materials made of biofuel-resistant material, as well as careful removal of the database that got on the paintwork. In some cases, you need to change the engine oil more often due to the possible rarefaction of the database. Some increase in noise and smoke level at cold start is possible, at the lowered values of temperature depressant additives should be applied. It is necessary to control the water content in the database (due to its high hygroscopicity) to avoid the danger of microorganisms, the formation of peroxides and corrosive effects of water, including the elements of fuel equipment.
References
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УДК: 662.99
Кобылкина А.В., Кобылкин М.В., Риккер Ю.О.
Забайкальский государственный университет DOI: 10.24412/2520-6990-2021-16103-17-19 ОЦЕНКА ЭФФЕКТИВНОСТИ РЕКУПЕРАЦИИ ТЕПЛОТЫ «СЕРЫХ» СТОКОВ МАЛОГАБАРИТНЫМИ УСТРОЙСТВАМИ
Kobylkina A. V., Kobylkin M.V., Rikker Yu.O.
Transbaikal State University
ESTIMATION OF THE EFFICIENCY OF A HEAT RECOVERY OF "GRAY" WASTEWATER BY
SMALL DEVICES
Аннотация
В данной статье рассматривается технология рекуперации тепла из «серых» стоков, осуществляемая непосредственно с применением рекуперативного теплообменного аппарата, проводится разработка конструкции основных узлов рекуператора и математическое моделирование его работы.
Abstract
This article discusses the technology of heat recovery from "gray" wastewater, carried out directly with the use of a recuperative heat exchanger, the design of the main units of the recuperator and mathematical modeling of its operation are being developed.
Ключевые слова: энергосбережение, ГВС, рекуперация теплоты, «серые» сточные воды, математическое моделирование, тепловой баланс.
Key words: energy saving, hot water supply, heat recovery, "grey" wastewater, mathematical modeling, heat balance.
Проблемы энергосбережения, нехватки и нерационального использования топливно-энергетических ресурсов, реализации потенциала повышения энергоэффективности, а также детальной проработки политики в области энергосбережения относятся к актуальным проблемам российской экономики.
На сегодняшний день в России пристальное внимание уделяется мероприятиям по энергосбережению и повышению энергетической эффективности и снижению энергопотребления на подогрев воды в системах горячего водоснабжения (ГВС). Данные мероприятия реализуются в соответствии с законодательными актами, включающими Федеральный закон N 261-ФЗ «Об энергосбережении и о повышении энергетической эффективности и о внесении изменений в отдельные законодательные
акты Российской Федерации» [4], национальными стандартами ГОСТ 31166-2003, ГОСТ 31167-2003, ГОСТ 31168-2003, ГОСТ Р 54964-2012, сводами правил СНиП 23-02-2003, СНиП 31-01-2003 [1, 2], постановлением Правительства РФ от 11.02.2021 N 161 «Об утверждении требований к региональным и муниципальным программам в области энергосбережения и повышения энергетической эффективности» [3] и другими нормативными документами, которые дают важнейшие предпосылки к разработке новых технологических решений, направленных на сокращение потребления энергетических ресурсов во всех сферах отрасли теплоснабжения.
Расширить рынок технологий, направленных на повышение энергоэффективности и снижения энергопотребления на подогрев воды в системах
