Due to increasingly stringent fuel consumption and emission regulation,improving thermal efficiency and reducing particulate matter emissions are two main issues for next generation gasoline engine.Lean burn mode coul...Due to increasingly stringent fuel consumption and emission regulation,improving thermal efficiency and reducing particulate matter emissions are two main issues for next generation gasoline engine.Lean burn mode could greatly reduce pumping loss and decrease the fuel consumption of gasoline engines,although the burning rate is decreased by higher diluted intake air.In this study,dual injection stratified combustion mode is used to accelerate the burning rate of lean burn by increasing the fuel concentration near the spark plug.The effects of engine control parameters such as the excess air coefficient(Lambda),direct injection(DI)ratio,spark interval with DI,and DI timing on combustion,fuel consumption,gaseous emissions,and particulate emissions of a dual injection gasoline engine are studied.It is shown that the lean burn limit can be extended to Lambda=1.8 with a low compression ratio of 10,while the fuel consumption can be obviously improved at Lambda=1.4.There exists a spark window for dual injection stratified lean burn mode,in which the spark timing has a weak effect on combustion.With optimization of the control parameters,the brake specific fuel consumption(BSFC)decreases 9.05%more than that of original stoichiometric combustion with DI as 2 bar brake mean effective pressure(BMEP)at a 2000 r/min engine speed.The NO_(x) emissions before threeway catalyst(TWC)are 71.31%lower than that of the original engine while the particle number(PN)is 81.45%lower than the original engine.The dual injection stratified lean burn has a wide range of applications which can effectively reduce fuel consumption and particulate emissions.The BSFC reduction rate is higher than 5%and the PN reduction rate is more than 50%with the speed lower than 2400 r/min and the load lower than 5 bar.展开更多
在一台4缸2.0 L汽油发动机上试验研究过量空气系数、有效压缩比、废气再循环(exhaust gas recircu-lation, EGR)率对发动机油耗和热效率的影响。结果表明:采用稀燃可以提高发动机热效率,过量空气系数由1.0增大到1.6,发动机热效率提高约5...在一台4缸2.0 L汽油发动机上试验研究过量空气系数、有效压缩比、废气再循环(exhaust gas recircu-lation, EGR)率对发动机油耗和热效率的影响。结果表明:采用稀燃可以提高发动机热效率,过量空气系数由1.0增大到1.6,发动机热效率提高约5.7%,但继续增大稀释程度将导致油耗增加、热效率降低;当有效压缩比为12.7时,发动机热效率最大,为44.1%,进一步增大压缩比产生爆震,需要推迟点火时刻,导致燃烧持续期增加、发动机热效率降低;EGR率为4.6%时,发动机热效率最大,为44.4%,EGR率较大导致燃烧不稳定,出现发动机失火等问题。展开更多
基金supported by Shanghai Automotive Industry Technology Development Foundation and the National Natural Science Foundation of China(Grant No.51861135303).
文摘Due to increasingly stringent fuel consumption and emission regulation,improving thermal efficiency and reducing particulate matter emissions are two main issues for next generation gasoline engine.Lean burn mode could greatly reduce pumping loss and decrease the fuel consumption of gasoline engines,although the burning rate is decreased by higher diluted intake air.In this study,dual injection stratified combustion mode is used to accelerate the burning rate of lean burn by increasing the fuel concentration near the spark plug.The effects of engine control parameters such as the excess air coefficient(Lambda),direct injection(DI)ratio,spark interval with DI,and DI timing on combustion,fuel consumption,gaseous emissions,and particulate emissions of a dual injection gasoline engine are studied.It is shown that the lean burn limit can be extended to Lambda=1.8 with a low compression ratio of 10,while the fuel consumption can be obviously improved at Lambda=1.4.There exists a spark window for dual injection stratified lean burn mode,in which the spark timing has a weak effect on combustion.With optimization of the control parameters,the brake specific fuel consumption(BSFC)decreases 9.05%more than that of original stoichiometric combustion with DI as 2 bar brake mean effective pressure(BMEP)at a 2000 r/min engine speed.The NO_(x) emissions before threeway catalyst(TWC)are 71.31%lower than that of the original engine while the particle number(PN)is 81.45%lower than the original engine.The dual injection stratified lean burn has a wide range of applications which can effectively reduce fuel consumption and particulate emissions.The BSFC reduction rate is higher than 5%and the PN reduction rate is more than 50%with the speed lower than 2400 r/min and the load lower than 5 bar.
文摘在一台4缸2.0 L汽油发动机上试验研究过量空气系数、有效压缩比、废气再循环(exhaust gas recircu-lation, EGR)率对发动机油耗和热效率的影响。结果表明:采用稀燃可以提高发动机热效率,过量空气系数由1.0增大到1.6,发动机热效率提高约5.7%,但继续增大稀释程度将导致油耗增加、热效率降低;当有效压缩比为12.7时,发动机热效率最大,为44.1%,进一步增大压缩比产生爆震,需要推迟点火时刻,导致燃烧持续期增加、发动机热效率降低;EGR率为4.6%时,发动机热效率最大,为44.4%,EGR率较大导致燃烧不稳定,出现发动机失火等问题。
