Research Of Residual Gas In Gasoline Engine

With the environmental issues been the general interest, the major of which is the automobileexhaust, the regulation of emissions becoming more and more strictly. There are many methods forreducing the toxic of automobile exhaust, but what this paper studies is iEGR (internal exhaust gasrecirculation), which is one of the low-cost and valid. Because the interaction of cylinders have veryfew influence on the volumetric of iEGR, therefore, the piston of first, second and third cylinderwere removed for simplifying the research.Based on the simulation software GT-POWER and FIRE, a model is built for testing theeffects of iEGR on the performance and emissions of gasoline engine at different valve timing.After comparing, we get the better valve timing to reducing the NOx emission at the cost ofperformance in the range of acceptable. After that, different simulations were applied on the modelestablished before at three different kinds of valve timing.Through analysis after the simulation, the valve timing can be optimized at different operatingcondition. After optimization, IVO is put off by5°CA and EVC is advanced by15°CA at maxpower operating condition. What is more, the rate of iEGR increased from8.5%to10.7%，thepower declined from21.1KW to19.6KW, the reducing rate is7.1%; the ISFC increase from190.7g/KW.h to195.8g/KW.h, the increasing rate is2.6%; the emission of NOx reducing from107ppmto89ppm, the decline rate is16.8%.At maximum torque operating condition, IVO remain unchanged, but the EVC is advancedby10°CA. After the optimization, the power declined from25.3KW to22.9KW, the reducing rateis12.6%; the ISFC increase from196.5g/KW.h to205.2g/KW.h, the increasing rate is4.7%; theemission of NOx reducing from109.4.5ppm to82.7ppm, the decline rate is20.4%.Overall the iEGR influence both the performance and emissions of gasoline engine obviously.With the increasing of iEGR, the max pressure and the peek heat release rate in cylinder is reducing,and the burning center backwards also, therefore the emission of NOx reduced, but the powerperformance and fuel consumption were both deteriorated on a small scope.