A set of GDI system for ethanol injection is installed on a F188 diesel engine, and the diesel supply system of the original diesel engine is used for diesel injection. The computational fluid dynamics software FIRE is adopted to establish a 3D combustion model of the ethanol -diesel direct injection engine. The total heat energy of the fuel is equivalent to that of the original diesel engine under the same condition. As the diesel injection starting point is 344°CA and there is simultaneous diesel and ethanol injection, the ethanol injection starting points at 344°CA, 338°CA, 332°CA, 326°CA and 320°CA are subject to 3D simulation for fuel injection, mixed gas formation and combustion and pollutant formation process. The results show that, the earlier the ethanol injection is, the steeper the heat release rate curve during the initial combustion period, the higher the peak value, and the shorter the heat release duration are, and the higher the maximum combustion pressure, the headmost phase of the maximum combustion pressure and the more obvious the premixed combustion are. Earlier ethanol injection starting point and quicker rise of the temperature curve of the cylinder bring the headmost phase of the highest average temperature in the cylinder, and higher average temperature in the cylinder brings higher NO concentration. The ethanol injection starting point shall be earlier than the diesel injection starting point injection, for it is the most favorable for reducing soot generation.
A field vibration test was conducted on the coal crusher chamber of a thermal power plant to evaluate its vibration performance. The vibration displacements and velocities of the structure, coal crusher body, and vibration-isolation platform were tested. The vibration safety of the coal crusher chamber and the vibration-isolation efficiency of the spring vibration-isolation system were evaluated based on the test results, and the reason the vibration exceeded the limit was analyzed. This study showed that the vibration displacement of a coal crusher with a spring vibration-isolation system met the code requirements, but the equipment had greater vibration displacements, which were related to the connection between the equipment and the platform. Compared to a steel platform, the vibration displacement of a concrete platform was smaller, and the vibration-isolation efficiency was greater. The vibration displacements of the coal crusher body could be reduced by controlling the vibration displacements of the platform.
For the purpose of providing a scientific reference for improving energy conservation and performance of marine diesel engine, the thermal balance analysis and exergy balance analysis and emission research on ethanol diesel-oil alternative fuel of the existing diesel engine are performed. All necessary data are obtained from an actual diesel engine of KTA50-M2 which is used in a boat located in Dalian. The result shows that engine performance parameters are of no big change, however, the exhaust emissions are significantly reduced.
The coal crusher generates large vibrations when crushing coal blocks, which can affect the equipment itself, as well as the safety of the structure. In order to study the dynamic characteristics of coal crusher, a finite element model of the coal crusher chamber in the Shangluo power plant was built by using ABAQUS. Firstly, modal and harmonic response analyses were conducted, and the comparison shows that the numerical results are basically in accordance with the test results. Then, shock absorption research was performed using a parametric analysis that included the stiffness and position of the spring vibration isolator, the mass, and material of the vibration-isolation platform. Finally, the dynamic coefficient of a coal crusher was discussed. The results showed that, compared with the stiffness of the spring vibration isolator, the mass of the vibration-isolation platform had more influence on the vibration displacement of the coal crusher. To achieve better vibration isolation, the concrete platform is suggested, and the eccentricity of the spring vibration isolator should not exceed 5%. When static design method is adopted to calculate the bearing capacity of the supporting structure subjected to the dynamic load of the coal crusher, the dynamic coefficient of a coal crusher is suggested as 1.5.
The developed corn stubble harvester can simultaneously finish such as the digging, picking up, cleaning, collection and Stripy laying stubble process and so on, but it cost more man-hour time because of the high digging resistance and high engine power consumption in digging stubble works. The digging spring tooth for corn stubble harvester including self-exited vibration S-shaped spring handle and curved chisel-shaped bionic tooth is designed based on the mechanism of drag reduction of self-excited vibration and bionic drag reduction for reduce digging resistance and power consumption, and the statics analysis of digging spring tooth is done by ANSYS software, the stress and strain distribution diagrams show the design is reasonable.
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