火花点火缸内直喷灵活燃料发动机的开发

Development of a Spark-Ignited Direct Injection Flexible Fuel Engine for Gasoline and Alcohol Fuels

对一台采用火花点火、缸内直喷、周向分层燃烧系统的发动机在燃用甲醇、乙醇和汽油时系统参数进行优化,获得系统燃用这三种燃料时各自的最优参数。根据优化结果不同的参数对发动机性能影响的程度进行折中,获得灵活燃料发动机的系统参数,实现了在不改动发动机的前提下灵活燃用此三种燃料。发动机性能研究表明:由于采用分层燃烧,灵活燃料发动机具有与直喷柴油机相当的热效率,在负荷特性上,燃用醇类燃料和汽油时的NOX排放分别仅为柴油机的10%～40%和21%～78%,CO排放低于1%,HC排放略高于柴油机,燃用醇类燃料时可实现无烟燃烧,燃用汽油时仅在高负荷运转时存在少许碳烟。

By optimizing the main parameters of an engine with a spark-ignited direct injection circularly stratified-charge (DICSC) combustion system when it operates on methanol, ethanol or gasoline, the optimum parameters of the combustion system for the three fuels are obtained respectively. By compromising the different system parameters for the three fuels in terms of their effect on engine performances, the combustion system parameters of the flexible fuel engine (FFE) are obtained. It can be realized for the FFE to operate on methanol, ethanol or gasoline without changing the engine. Performances of the FFE are studied. The results show that the FFE has the advantages of high thermal efficiency equivalent to that of direct injection diesel engine due to adopting the mixture stratification. NOx emissions for alcohol and gasoline operations are only 10%-40% and 21%-78% of diesel engine's respectively at load characteristics. In the FFE, CO emission is lower than 1%, and HC emission is slightly higher than that of diesel engine. Smokeless combustion can be realized for alcohol operation at any operating conditions, and there exists little smoke emission for gasoline operation only at high load.