摘要
针对一台电控共轨二甲醚发动机,研究了乙醇掺混比例和预喷定时对发动机燃烧及排放的影响。结果表明,采用预喷策略后,混合气放热模式由单阶段放热转变为两阶段放热,主喷定时对缸内燃烧规律影响明显变弱。随着预喷定时的提前,放热模式由两阶段转变为三阶段,NO_x排放显著降低,CO和HC排放逐渐升高。最大压力升高率在预主喷间隔角为20°CA时,由预喷燃料燃烧引起,而预喷定时提前后主要由主喷燃料燃烧引起。相同预喷定时工况下,随着乙醇掺混比例的增加,预喷燃料的放热峰值降低,放热始点延后;NO_x排放降低,CO和HC排放增大。
Effects of blend ratios and pilot injection timing on the combustion and emission characteristics were investigated in an electronically controlled common-rail DME engine.The results show that after adopting pilot injection strategy,the heat release mode of the mixed gas transforms from single-stage to two-stage heat release,and the effect of injection timing is obviously weakened.With the advance of pilot injection timing,the heat release mode transforms from two stages to three stages and NO_x emissions are significantly reduced while CO and HC emissions gradually increased.The maximum pressure rise rate is caused by the combustion of the pilot injection fuel when the pilot-main interval is 20°CA,or caused mainly by the combustion of the main injection fuel when pilot injection advances.Under the same pilot injection timing,with the increase of ethanol ratio,the peak heat release rate of the pilot injection fuel decreases and the start of heat release retards,NO_x emissions decrease and CO and HC emissions increase.
出处
《汽车工程学报》
2017年第4期235-243,共9页
Chinese Journal of Automotive Engineering
基金
国家自然科学基金(91441124)
上海浦江计划项目(11PJD014)
浙江省科技计划项目(2014C31033)
关键词
二甲醚发动机
乙醇
掺混比例
预喷定时
燃烧
排放
dimethyl ether engine
ethanol
blend ratios
pilot injection timing
combustion
emissions
