جستجوی مقالات مرتبط با کلیدواژه « Diesel Engine » در نشریات گروه « مکانیک »

In this research, the effective factors on the liner failure of the turbocharged engine (16rk215T) of the locomotive have been investigated. By preparing three liner samples from different manufacturers and sending them to the laboratory, the mechanical properties, including hardness and tensile strength, as well as the percentage of constituent elements and the difference in their values in different samples, were studied. Next, the effect of the weight percentage of different elements on the mechanical properties of gray cast iron was investigated. By preparing microscopic images at 100x magnification, the background structure was seen. Also, the shape and arrangement of lamellar-graphite in different samples were compared with each other and it effect on the fracture and crack growth in the liner was investigated. Three samples of liner, grade and material have been determined. With the appearance of eutectic phosphide in the structures of two samples A (broken liner) and B (liner with crack), as well as the high percentage of phosphorus, structural defects and the presence of dislocations in the grain cause the failure of these samples. Also, non-uniform production of lamellar-graphite in these two samples, its short length and thickness increases strength, reduces absorption and reduces energy.

The investigation of alternative fuels, such as biodiesel, have been prompted by the detrimental emissions resulting from the combustion of fossil fuels. Undoubtedly, the primary concern in fuel selection lies in the examination of emissions. Hence, the present study aims to examine the performance and environmental life cycle assessment methodologies of a dual fuel diesel engine. Furthermore, a fuel blend is made by combining biodiesel sourced from sunflower oil with varying concentrations of bioethanol (3%, 5%, and 7%) and pure biogas, with a percentage ranging from 50% to 80%. This fuel blend is intended for use in the combustion process. In this study, a total of eight fuel samples were meticulously produced and subsequently examined, alongside diesel fuel which served as the control fuel. The entire life cycle evaluation encompasses several stages, starting with the manufacturing of inputs to the combustion of fuel samples. This includes the extraction of oil from sunflower seeds, the production of biodiesel and bioethanol, as well as the generation of natural gas produced from pure biogas. These processes are regarded as captivating and pioneering topics within the field. The provided samples underwent combustion within a dual fuel engine. The findings indicate that the B5 fuel sample, when combined with a 3% bioethanol additive, demonstrates superior engine performance and reduced exhaust emissions. Furthermore, enhanced conditions were achieved in terms of engine performance and exhaust emissions when operating at the lowest rate of natural gas fractionation, which was 50%. The findings of a thorough life cycle evaluation, which examines the entire process from farm to combustion, indicate that the blend B5E7, consisting of 50% natural gas portion at maximum engine load, demonstrates both environmental friendliness and appropriate performance characteristics.

Diesel engines are considered the main sources of energy production and diesel fuel consumption. The use of biodiesel fuel as a part of diesel engines can have a positive effect on reducing the use of fossil resources and the emission of pollutants. Using biodiesel fuel, along with its advantages, has disadvantages such as increasing the emission of nitrogen oxides, which is considered a toxic gas. Many researchers have proposed different additives to cover some of the disadvantages of biodiesel fuel. In this article, two types of oxygen additives, including dimethyl carbonate and n-butanol, were combined with small amounts in B2 (2% biodiesel and 98% diesel) and B5 (5% biodiesel and 95% diesel) fuels. Using small amounts of these additives can reduce the cost of fuel production. Based on the obtained results, B2D10N10 and B2D10N0 fuel samples were able to increase the braking power of the diesel engine by about 12 and 10%, respectively, compared to B2 fuel. On the other hand, the use of fuel samples containing dimethyl carbonate and n-butanol additives in B2 fuel reduced the special brake fuel consumption by about 18% compared to diesel fuel and about 32% Diesel engines are considered the main sources of energy production and diesel fuel consumption. The use of biodiesel fuel as a part of diesel engines can have a positive effect on reducing the use of fossil resources and the emission of pollutants. Using biodiesel fuel, along with its advantages, has disadvantages such as increasing the emission of nitrogen oxides, which is considered a toxic gas. Many researchers have proposed different additives to cover some of the disadvantages of biodiesel fuel. In this article, two types of oxygen additives, including dimethyl carbonate and n-butanol, were combined with small amounts in B2 (2% biodiesel and 98% diesel) and B5 (5% biodiesel and 95% diesel) fuels. Using small amounts of these additives can reduce the cost of fuel production. Based on the obtained results, B2D10N10 and B2D10N0 fuel samples were able to increase the braking power of the diesel engine by about 12 and 10%, respectively, compared to B2 fuel. On the other hand, the use of fuel samples containing dimethyl carbonate and n-butanol additives in B2 fuel reduced the special brake fuel consumption by about 18% compared to diesel fuel and about 32% compared to B2 fuel. Using the combined additives of dimethyl carbonate and n-butanol increased the thermal efficiency by an average of 15-30% compared to diesel, B2, and B5 fuels. The addition of dimethyl carbonate and n-butanol in combination in small amounts significantly reduced carbon monoxide emissions. The highest amount of carbon dioxide emission occurs in fuels containing the combined compounds of dimethyl carbonate, n-butanol, and B5, which was about 10-15% higher than the control sample. During the optimization process, the B2D3N2 fuel sample was selected as the optimal formulation in combining diesel fuel, biodiesel, dimethyl carbonate, and n-butanol.

Pressure fluctuations during fuel injection are one of the factors that negative effect on performance of diesel engine. These fluctuations are caused by the rapid opening and closing of the nozzles and the creation of pressure waves in the fuel rail. One way to control these pressure fluctuations is to change the injector design and use an accumulator in the injector. This study is performed to investigate the effect of adding accumulator on the injector to control pressure waves in the common rail fuel injection system of diesel engines. As the simulation results show, at injection pressure of 1000 bar and energizing time of 0.8 milliseconds, in the case of no accumulator, the maximum pressure fluctuation in the fuel rail is 1046 bar and the minimum pressure is 891 bar. By adding an accumulator with a volume of 4 cm3, the maximum pressure continued to decrease and reached 1023 bar, and the minimum pressure of the fuel rail increased by 17 bar, 943 bar. These changes are also noticeable in other pressures and energizing times, so the best accumulator that has the most impact on reducing pressure fluctuations is the accumulator with a volume of 4 cm3.

One of the novel strategies to improve the performance and emissions of diesel engines is the use of alternative fuels as well as suitable additives such as nanoparticles to diesel fuel. Nanofuels play an important role in the optimization of combustion processes, fuel consumption, and emissions. In this paper, the effect of adding different nanoparticles (cerium, aluminum, and copper oxide nanoparticles) at a concentration of 100 particles per million (ppm) to diesel fuel on the combustion process and emissions of diesel engines has been investigated by using FIRE computational fluid dynamics code. For validation, the in-cylinder pressure variations, the experimental peak pressure, and the angle of occurrence are compared with the numerical results. In addition, the experimental data of NOx, soot, power as well as brake specific fuel consumption were evaluated with numerical values. The results show that nanoparticles increase the amount of heat transfer to the fuel and decrease the ignition delay. Also, better mixing of fuel and air in cerium oxide nanoparticles compared to other nanoparticles improved the fuel ignition mechanism, which leads to more complete combustion and a 14.5% increase in power and also a 6% and 34% reduction in fuel consumption and soot compared to diesel fuel respectively. The only downside is the 31% increase in NOx, which can be reduced by catalytic converters.

In this study, the combination of biodiesel-diesel, ethanol-diesel, and ethanol-biodiesel-diesel emulsion blends on performance and emissions of a direct injection diesel engine was investigated. High purity ethanol in three levels of 2, 4 and, 6 by volume percent and biodiesel prepared from waste cooking oil in four levels of 5, 10, 15 and 20 by volume percent were mixed with pure diesel. Thus, 11 fuel samples were prepared which were shown with BxEy, that x and y represent the volume percent of biodiesel and ethanol in the prepared mixtures, respectively. The experiments were performed at full load with the change in engine speed from 800 to 1800 rpm, with the interval 200 rpm. The results showed that pure diesel has the lowest specific fuel consumption at all of the speeds compared to other prepared mixtures. Using of B15E6 blend, reduced the emission of carbon monoxide by 40% compared to pure diesel. This mixture also, reduced the emissions of carbon dioxide and hydrocarbon by 27 and 55% compared to pure diesel, respectively.

Numerous studies on using light fuels in compression ignition engines to reduce emission and increase efficiency have been done. The Reactivity Controlled Compression Ignition engines are one of these studies. Nevertheless, using heavy fuels vapor for achieving partially premixed combustion is not investigated. Using diesel fume (to upgrade conventional combustion to premixed combustion) resolves the need for a secondary fuel tank in a car. However, diesel fuel has heavy hydrocarbons and is a high reactivity fuel. So in this study, diesel has evaporated in a tank, and its vapor has injected into the intake air for studying a semi homogeneous combustion. The tests have performed at 2000 rpm (the speed of maximum torque). According to the achieved results, although diesel has heavy hydrocarbons and is a high reactivity fuel, adding diesel fumigation can reduce soot and NOx emissions up to 20% and 50%, respectively. Increasing load reduces the positive impact of adding diesel fumigation on soot and NOx emission reduction. However, the positive impact of adding diesel fumigation continues up to 80% of the full load. Adding diesel fumigation has no impact on cyclic variation and ringing intensity, but increases CO and HC emission. The evaporation of diesel averagely consumes 15% of brake power. Also on average, 5% of diesel evaporation energy can be supplied by recovering heat energy from the exhaust gas (warming up diesel from ambient temperature to the exhaust gas temperature).

Nowadays, due to the competitive market, quality evaluation criteria at different stages of production are very important. One of these criteria is reliability, which is calculated using statistical evaluations of after-sales service data in most cases or with the help of accelerated tests at the early stage of the product development life cycle. In this research study, various accelerated test scenarios in proportion to the stresses on the diesel engine have been conducted to evaluate the lifetime of the connecting rod parts. The considered criterion for the reliability analysis is the time between failures which is evaluated after collecting and classifying the data using accelerated tests and confirming independent and uniform distribution of data via MIL-Hdbk, Laplace’s, and Anderson-Darling functions. Finally, the distribution diagram of reliability at different operating times was drawn using log-logistic statistical distribution, according to the best agreement with the experimental results. The results depicted that the reliability of the connecting rod would be equal to (0.99 @ 177417 hrs.) and (0.95@ 212753 hrs.) kilometers of cumulative operation, respectively, and after 448240 kilometers it would be less than 0.05.

One of the major problems in the world is the supply of energy. Biodiesel is one of the alternative fuels and renewable energy sources. The use of B5 biodiesel in diesel fuel mixtures is common and most countries have planned to use B20 biodiesel. The use of natural gas in diesel engines and the study of the possibility of using it in high quantities is another new solution, which can reduce dependence on diesel fuel. In this study, biodiesel was produced from waste oil by transesterification process and used in two levels of 5 and 20% in diesel composition. Then natural gas was used in three levels of 60, 70, and 80% (% G / T) in the diesel engine. Engine tests were performed at full-load at 1500 rpm. In general, the test results showed that in conditions where biodiesel B20 was used in the composition of diesel fuel and gaseous fuel was used in the amount of 80% in a diesel engine, suitable conditions in terms of reducing emissions, increasing energy efficiency, and reducing economic costs were obtained; Under these conditions, compared to a conventional diesel engine, brake power, and energy efficiency increased by 8.86 and 29.06%, respectively. Also, brake specific fuel consumption, CO and CO2 were reduced by 26.5, 57.58, and 4.54%, respectively. Although the amount of NOx increased slightly, but, decreased the economic cost compared to diesel 26.47% $/kwh, so the results were valuable.

In recent decades, rising greenhouse gas emissions have become a major challenge and concern. Environmental pollution is one of the greatest human challenges of the 21st century. Improving the performance of internal combustion engines and reducing the amount of pollutant emissions has always been a concern for researchers. The use of alternative fuels and the control and adjustment of the lambda coefficient are known as the most effective ways to increase fuel efficiency, reduce pollution and improve engine mobility. Therefore, in this study, the relationship between air-to-fuel equilibrium ratio or lambda coefficient with engine performance and exhaust emissions of a diesel engine using diesel-ethanol fuel blends as an alternative fuel at 1700, 1800 and 1900 rpm engine speeds has been investigated. The results showed that increasing the percentage of ethanol in the diesel-ethanol fuel blend increased the lambda coefficient. This increase reduced engine power and torque. The highest power reduction was achieved at 1900 rpm at the rate of 1.18 kW and the maximum torque reduction at 1800 rpm at the rate of 5.94 N.m. As the lambda coefficient increased, the exhaust oxygen output increased by 42.89% at 1700 rpm. The increase in lambda also reduced the emissions of unburned hydrocarbons and carbon monoxide. Thus, the highest reduction of these pollutants was 23.8% at 1800 rpm and 38.75% at 1900 rpm, respectively. Also, increasing the lambda coefficient slightly increased the nitrogen oxides. Finally, due to the use of diesel-ethanol fuel blends and as a result of increasing the lambda coefficient, a significant reduction in the amount of emissions of exhaust gases was achieved.