进气氧浓度和喷油正时对柴油机低温燃烧特性影响的试验研究

Experimental Study on the Effect of Intake Oxygen Concentration and Injection Timing on Low Temperature Combustion in a Diesel Engine

在一台四缸增压直喷式柴油机上进行不同进气氧浓度和喷油正时对柴油燃料低温燃烧特性影响的试验研究。研究结果表明:降低进气氧浓度,缸内压力和放热率峰值迅速下降,放热率始点推迟,滞燃期延长,有效燃油消耗率增加,氮氧化物(NO_x)排放大幅降低,CO排放增加。当进气氧浓度较高时,碳烟排放变化较小,而随着进气氧浓度的进一步下降,碳烟排放急速增加。在相同的进气氧浓度下,随着喷油正时的提前,滞燃期先减小后增大,CA50逐渐向上止点靠近,最大压力升高率增大,燃油消耗率下降,NO_x和碳烟排放增大,CO排放减小。

The effect of different intake oxygen concentration and fuel injection timing on combustion and emission characteristics under low temperature combustion conditions were experimentally investigated on a 4 cylinder turbocharged direct injection diesel engine fuelled with pure diesel. The results show that, the decrease of inlet oxygen concentration will make the maximum combustion pressure and heat release rate decreased rapidly, the heat release rate delayed and the ignition delay period prolonged, the brake specific fuel consumption increased, meantime, the NO~ emission decreased significantly and the CO emission increased. With the increase of intake oxygen concentration the soot emission is essentially constant and with the further decrease of intake oxygen concentration the soot emission increases rapidly. At the same intake oxygen concentration, the advance of fuel injection timing will make the ignition delay period decreased first and then increased, CA50 gradually closed to the top dead center, the maximum pressure rise rate increased, and the brake specific fuel consumption decreased while the NOx and soot emissions increased and the CO emission decreased.