用汽油和甲醇燃油分层拓展HCCI燃烧高负荷的试验研究

在一台单缸HCCI发动机上研究了进气道喷射汽油缸内喷射甲醇形成汽油甲醇燃油分层的HCCI燃烧排放特性,探索了其拓展HCCI燃烧高负荷的潜力。试验结果表明:在汽油HCCI燃烧中喷射甲醇能够有效降低缸内混合气的温度,推迟着火时刻,延长燃烧持续期,从而降低压力升高率和缸内最高燃烧压力,有利于拓展HCCI燃烧高负荷。一定的HCCI负荷工况存在最佳的汽油甲醇比例,且汽油甲醇最佳比例随着负荷的增加不断减小。在最大压力升高率0.5MPa/°CA和较高的指示效率的限制下,自然吸气条件下采用汽油和甲醇燃油分层的HCCI燃烧最高负荷比汽油HCCI燃烧提高了近50%,达到0.62MPa。

Experimental Research on High Load Extension of HCCI Combustion Using Gasoline and Methanol Stratification

Effects of gasoline and methanol stratification on HCCI combustion and emissions were studied in a single-cylinder HCCI engine with gasoline port injection and methanol in-cylinder injection.The experimental results show that the methanol direct injection in gasoline HCCI combustion can decrease mixture temperature,retard ignition timing and extend combustion duration,the max.pressure rise rate and the max.cylinder pressure can be reduced consequently,which is good for HCCI high load extension.There is an optimal gasoline methanol ratio for a certain HCCI load condition,and it decreases with load increasing.Within the limits of max.pressure rise rate of 0.5MPa/°CA and high indicated thermal efficiency,the max.IMEP can be extended up to 0.62MPa,nearly 50%,by using the optimal fuel stratification under natural aspiration conditions.