中文摘要：

在一台四冲程六缸增压中冷的高压共轨柴油机上采用进气总管喷射无水甲醇的方式进行柴油/甲醇组合燃烧实验（DMCC）.通过改变共轨柴油喷射的主喷射时刻以及甲醇的喷射量,对柴油机燃烧和尾气排放进行研究.试验发现,纯柴油模式下,压缩冲程缸压随着喷油提前角的减小而增大,推迟喷油,后燃期延长,排气压力增大.甲醇替代率为30%时,随着喷油提前角的增大,峰值缸压和峰值放热率均增大.在柴油/甲醇双燃料燃烧模式下主喷射时刻对减少柴油机氮氧化合物（NOx）排放具有较好的作用,同一替代率情况下NOx排放随着主喷射时刻的推后而减少;主喷射时刻对碳烟（Soot）排放的影响则比较复杂,纯柴油模式下碳烟的排放随着主喷射时刻的提前逐步减少,而柴油甲醇二元燃料燃烧（DMDF）模式下碳烟的排放则随着主喷射时刻的提前呈现出先上升后下降的趋势;DMDF模式下主喷射时刻提前CO、HC排放均降低,且替代率越大下降趋势越明显.

英文摘要：

The effect of main injection timing of common rail fuel system on combustion and exhaust emissions from a diesel/methanol dual fuel （DMDF） engine modified from a 6-cylinder turbocharged intercooling diesel engine with electrically controlled high pressure common rail injection system was investigated by changing the main injection timing and the amount of methanol in combustion. The test condition is chosen at 50% of load and 1340 r·min-1, typical during engine running. The test results show that the cylinder pressure and exhaust pressure increase with the retardation of main injection timing. At 30% substitution ratio of methanol, maximum cylinder pressure and maximum heat release rate increase with the advance of main injection timing. The main injection timing has a preferable effect on reducing NOx at DMDF mode. At the same ratio of methanol substitution, NOx emissions decrease with the retardation of main injection timing. The main injection timing has a complicated influence on soot emissions. The soot emissions gradually reduce as the main injection timing advances on the pure diesel mode, while at the DMDF mode the soot emissions tend to decrease after a slight increase. At the DMDF mode the main injection timing has a slight effect on CO, HC, methanol and oxymethylene emissions. Emissions of CO and HC decrease with the advance of main injection timing, and more significantly as the methanol substitution ratio further increases.