Simulant And Experimental Study Of Cylinder-to-Cylinder Distribution Of EGR Ratio On JX493Diesel Engine

For multi-cylinder diesel engine with EGR technology, even distribution of EGR rate in each cylinder can ensure good combustion quality and emission. A portion of the exhaust gas is mixed with the air then the mixture gas is injected into the cylinder for combustion, increasing the heat capacity of the mixture, while reducing the maximum temperature of the combustion, to reduce the generation of NOx.In this paper, CFD analysis method is used to study the even distribution of EGR rate in each cylinder on a493diesel engine. Firstly, the structure of the prototype EGR outlet pipe is optimized and the intake manifold models are established, and3D CFD software AVL Fire is used to carry out the results between the two kinds of models, including the simulation analysis process, and the results of optimization analysis(The simulation conditions given for the power72kW,speed3600rpm, the EGR rate of15%). The results show that EGR rate of the optimized piping is8.99%which is obviously better than44.79%, the optimized piping is better for the even distribution of the EGR rate.For engine performance test stage,firstly,performance bench is used to verify optimized manifold B is good for the evenly EGR rate in each cylinder,using the NOx concentration in each cylinder to reflect the deviation of EGR rate in each cylinder.Three operating points are selected:1500rpm,150N;2800rpm,134N;3200rpm,155N. During the test,the calibration means is also used to artificially increase NOx emissions, in order to distinguish the deviation of the concentration of NOx better.The test results and the simulation results are basically coincided,the maximum deviation of the original pipe EGR rate is more than10%, and optimized piping meet the design requirement which is below10%.Subsequently,emissions and fuel economy tests are done on the493diesel engine, the A-type intake manifold is firstly tested, and then replace the optimized manifold pipe B to do a comparison test.From1200to3000rpm,select the appropriate load to test the NOx, HC emissions per200rpm while recording the fuel consumption BSFC.The test results show that the optimized manifold B have good effect on the NOx emission, and the BSFC has also been improved, especially in the low-speed region.These results show that the optimization model B is not only conducive to the uniform distribution of the EGR rate, but also to improve the engine combustion, reduce fuel consumption.