F-T柴油对电控高压共轨柴油机燃烧特性的影响

摘要

An experiment is carried out on a Euro III diesel engine with high-pressure common rail system, to compare the combustion characteristics of diesel engine fueled with Fischer-Tropsch (F-T) diesel fuel and diesel fuel. The results showed that F-T diesel fuel significantly shortens the ignition delay period and decreases peak value of heat release rate during a pilot injection period compared with diesel fuel when two types of fuels keep the same pilot and main injection pulse-width. In the main injection phase, F-T diesel fuel shows slight advance of ignition timing compared with diesel fuel, but the peak values of heat release rates are approximately equivalent for two types of fuels. Compared with diesel fuel, the combustion duration of F-T diesel fuel is significantly shortened during the pilot injection period, but doesn't show significant difference during the main injection period. In post injection period, F-T diesel fuel exhibits advanced ignition, lower combustion duration and closer peak value of heat release rate compared with diesel fuel. Compared with diesel fuel, the maximal pressure rise rate for F-T diesel fuel caused by pilot injection is decreased clearly. However, during main injection period, maximal pressure rise rate of F-T diesel fuel is slightly higher than that of diesel fuel, and is about 20% as much as that of F-T diesel fuel pilot injection. The in-cylinder pressure induced by diesel fuel combustion tends to be higher than that by F-T diesel fuel in any injection period. Moreover, the torque of F-T diesel fuel measured from full-load performance is decreased slightly and the specific fuel consumption is reduced by 7.1%, while the thermal efficiency is increased by 4.5% than that of diesel fuel.%在满足国Ⅲ排放的电控高压共轨柴油机上,对比研究了燃用F-T柴油和普通柴油的燃烧特性.在柴油机预、主喷射脉宽未做调整情况下,F-T柴油的滞燃期较柴油明显缩短,预喷射放热峰值明显低于柴油.主喷射时F-T柴油较柴油先着火现象不明显,但两者放热峰值相差不大.F-T柴油的预喷射燃烧持续期较柴油大幅缩短,主喷射时相差不大.后喷射时,F-T柴油先于柴油着火,放热峰值与柴油相当,燃烧持续期略低于柴油.同柴油相比,预喷射时F-T柴油的最高压力升高率明显降低,而主喷射时F-T柴油高于柴油,但只有预喷射时的20％左右.整个燃烧过程柴油缸压略高于F-T柴油.另外,F-T柴油的外特性扭矩略有下降,有效燃油消耗率较柴油平均降低了7.1％,有效热效率平均提高了4.5％.