Y. Niknam; D. Mohammad Zamani; M. Gholami Par-Shokohi
Abstract
This study presents the effects of compressed natural gas fuel on a four-cylinder compression ignition engine. Compressed natural gas as the main fuel and diesel fuel as the igniter were used to investigate performance and emissions from the dual fuel engine. According to the engine speed and load, the ...
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This study presents the effects of compressed natural gas fuel on a four-cylinder compression ignition engine. Compressed natural gas as the main fuel and diesel fuel as the igniter were used to investigate performance and emissions from the dual fuel engine. According to the engine speed and load, the amount of diesel fuel as igniter was adjusted using mechanical changes in the governor, while no ignition system was used. The engine experimental tests were performed at engine speeds of 1200, 1400, 1600, 1800 and 2000 rpm, using diesel fuel and dual fuel. These data were collected in the Engine Research Center of Tabriz Motorsazan Company and experimental runs were repeated three times. The maximum torque of the engine in diesel mode was 360 N m at 1400 rpm. Compared to the diesel mode, the dual fuel mode showed the maximum torque by 334 N m at 1600 rpm, which is about 26 N m less than that gained from the diesel mode. Considering emissions analysis at 2000 rpm, it is seen that the amount of NOX, HC, CO2 and CO emissions in the dual fuel mode was 20, 53, 16 and 86% more than diesel mode, respectively. However, O2 and soot showed the highest reduction at 2000 rpm for dual fuel mode by 51% and 69% respectively. This study indicated that there was a considerable enhancement in exhausted emissions when the injection of the diesel fuel as igniter was done mechanically. In this regard, control the amount and time of the igniter injection could likely be helped for better control of emissions. Therefore, further research on the modification of the diesel injection system as igniter or CNG injection system is needed towards reducing emissions.
G. Khoobbakht
Abstract
IntroductionIn recent years, the exergy analysis method has been widely used in the design, simulation and performance assessment of various thermal systems. In this regard, this method may be applied to various types of engines for identifying losses and efficiencies. This analysis is based on the second ...
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IntroductionIn recent years, the exergy analysis method has been widely used in the design, simulation and performance assessment of various thermal systems. In this regard, this method may be applied to various types of engines for identifying losses and efficiencies. This analysis is based on the second law of thermodynamic. Exergy is a potential or quality of energy. It is possible to make sustainable quality assessment of energy. In this study, the second law of thermodynamics is employed to analyze the quantity and quality of exergy in a fourstroke, four-cylinder, diesel engine using diesel fuel and biodiesel fuel.Materials and MethodsFour experiment variables in the present study including the operating parameters, load and speed, and the added volume of biodiesel of diesel fuel were considered as effective factors on the Break exergy efficiency. Designs that can fit model must have at least three different levels in each variable. This is satisfied by Central Composite Rotatable Designs (CCRD). Similar to the case of the energy analysis, the same assumptions were valid for exergy analysis; the whole engine was considered to be a steady-state open system. For exergy analyses, the entire engine was considered to be a control volume and a steady-state open system. Fuel and air enter, and mechanical work, heat loss and exhaust gases leave the control volume at a constant rate. The exergy balance for the control volume can be stated as. where is the exergy transfer rate associated with the heat loss from the control volume to the environment, assumed to be through cooling water; is the exergy work rate, which is equal to the energetic work rate; is the mass flow rate; is specific flow exergy; and is the exergy destruction (irreversibility) rate. Results and Discussionexergy efficiency increased with increasing engine load. This relationship could be attributed to the reason that brake power increased with increasing engine load, and the other side, there was a positive direct relationship between brake power and exergy efficiency, resulting in an increase of exergy efficiency. Although fuel consumption increased along with increasing engine load, increase in the brake power was much greater than increase in the fuel consumption. On the other hand, an increase in the engine load enhanced combustor temperature which was provided an appropriate condition for combustion and caused an increase in cylinder pressure. At all engine operating conditions, with increasing engine speed, the thermal efficiency at first increased, at moderate speed reached to a maximum amount and finally with more increase in engine speed, the thermal efficiency decreased. The initial increase in thermal efficiency could be attributed to the increase in air to fuel ratio and engine torque which caused an increase in the brake power. Decreasing thermal efficiency in high levels of engine speed could be caused by a decrease in volumetric efficiency of the combustion chamber, because of the time limit on filling cylinder. With increasing biodiesel concentration in the fuel blend, exergy efficiency decreased. The reason could be due to the lower calorific value and the higher viscosity of biodiesel compared to diesel fuel.ConclusionAt all engine operating conditions, the exergy efficiency of the engine increased with increasing engine load also with increasing percentages of biodiesel into synthetic fuel, exergy efficiency increased. 43.09% of the fuel exergy was completely destructed and was not convertible to work. The results of optimization indicated that the most exergy efficiency (37.72%) was occurred for the pure diesel at 2036 rpm and 95% load.
A. Safrangian; L. Naderloo; H. Javadikia; M. Mostafaei; S. S. Mohtasebi
Abstract
Introduction Vibrations include a wide range of engineering sciences and discuss from different aspects. One of the aspects is related to various types of engines vibrations, which are often used as power sources in agriculture. The created vibrations can cause lack of comfort and reduce effective work ...
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Introduction Vibrations include a wide range of engineering sciences and discuss from different aspects. One of the aspects is related to various types of engines vibrations, which are often used as power sources in agriculture. The created vibrations can cause lack of comfort and reduce effective work and have bad influence on the health and safety. One of the important parameters of the diesel engine that has the ability to create vibration and knocking is the type of fuel. In this study, the effects of different blends of biodiesel, bioethanol and diesel on the engine vibration were investigated. As a result, a blend of fuels such as synthetic fuel that creates less vibration engine can be identified and introduced. Materials and Methods In this study, canola oil and methanol alcohol with purity of 99.99% and the molar ratio of 6:1 and sodium hydroxide catalyst with 1% by weight of oil were used for biodiesel production. Reactor configurations include: maintaining the temperature at 50 ° C, the reaction time of 5 minutes and the intensity of mixing (8000 rpm), and pump flow, 0.83 liters per minute. A Massey Ferguson (MF) 285 tractor with single differential (2WD), built in 2012 at Tractor factory of Iran was used for the experiment. To measure the engine vibration signals, an oscillator with model of VM120 British MONITRAN was used. Vibration signals were measured at three levels of engine speed (2000, 1600, 1000 rpm) in three directions (X, Y, Z). The analysis performed by two methods in this study: statistical data analysis and data analysis using Adaptive neuro-fuzzy inference system (ANFIS). Statistical analysis of data: a factorial experiment of 10×3 based on completely randomized design with three replications was used in each direction of X, Y and Z that conducted separately. Data were compiled and analyzed by SPSS 19 software. Ten levels of fuel were including of biodiesel (5, 15 and 25%) and bioethanol (2, 4 and 6%), and diesel fuel. Data analysis by ANFIS: ANFIS is the combination of fuzzy systems and artificial neural network so that it has both benefits. This system is useful to solve the complex non-linear problems in agricultural engineering applications such as systems involved in the soil, plant and air. ANFIS by linguistic concepts can establish and inference non-linear relationship between inputs and outputs. In this research, modeling was generally performed by Toolbox of ANFIS and coding in MATLAB too. Five important and effective factors in modeling were optimized until the best ANFIS model is obtained. The five factors were: type of input fuzzy sets, the number of input fuzzy sets, fuzzy set of output, methods of optimization and the number of epochs. Results and Discussion Based on the total vibration acceleration values for different fuels in different rpm, pure diesel (B5E4D91) had the highest vibration and the lowest vibration was seen in the mixed fuel of B25E4D71. Based on the results, two combined fuel of (B25E2D73, B25E4D71) have the lowest vibration and highest amount of biodiesel fuel (25%). After them, three combined fuels of (B5E2D83, B5E4D81, and B5E6D79) have created more vibration and the lowest amount of biodiesel fuel in this study (5%) has created the greatest amount of vibration. With increasing engine speed, the number of combustion courses and piston shock per unit of time increases. As a result, the engine body vibration increases. The results are consistent with results from other researchers. Conclusion In this study, motor vibration of MF285 tractors, by replacing a portion of diesel fuel with biodiesel produced from canola oil and bioethanol, was investigated. In the beginning, necessary biodiesel fuel was produced by research reactor in biodiesel workshop, and then different percentages of diesel and bio-ethanol were mixed to biodiesel and ten combined fuels were created. Finally the effect of different fuel combinations and different engine rotational speeds on the tractor engine vibrations was studied based on a factorial randomized complete block design and then analyzed and modeled by ANFIS. The results showed that the vibration of pure diesel fuel had the highest vibration. Also, with increasing biodiesel fuel blends, the amount of vibration reduced significantly. Increase in engine speed had direct effect on increasing the amount of vibration. Also by increasing the percent of bioethanol from 0 to 4%, the amount of vibration was reduced then vibration value increased by raising the percent of bioethanol. After modeling and analyzing, our results showed that the best fuel in terms of having the lowest vibration motor was B25E4D71.
