后喷参数对柴油机排放影响的试验研究

Experimental Study on the Influence of Post-Injection Parameters on Diesel Engine Emission

以某型高压共轨柴油机作为试验样机,研究了在转速2850r·min^(-1),负荷率为75%的工况下,轨压、主喷正时、后喷油量及主-后喷间隔角对柴油机烟度、NO_x排放及燃油消耗率的影响。结果表明:较大的轨压可以降低烟度和燃油消耗率,而推迟主喷正时可以明显降低NO_x排放量;随着后喷油量的增加,NO_x排放逐渐降低,燃油消耗率逐渐增大,CO、HC和烟度排放呈现出先降低后上升的趋势;随着主-后喷间隔角的增大,NO_x排放逐渐降低,CO、HC排放和燃油消耗率逐渐增大,烟度排放呈现出先降低后上升的趋势;与单次喷射相比,引入后喷射能使NO_x和烟度的排放均有所降低,但燃油消耗率会有所增加;采用合理的后喷射参数可以实现柴油机排放和燃油消耗率的折中优化。

The influences of rail pressure,main injection timing and parameters of post-injection on smoke,NOxand fuel consumption rate of a high-pressure common-rail diesel engine were discussed at the operating conditions of 75% load rate with speed of 2850 r·min^-1.It is found that the smoke and fuel consumption rate are reduced with higher rail pressure.The amount of NOxemission is significantly reduced with delayed main injection timing.With the increase of post-injection quantity,NOxemission is decreased and fuel consumption rate is increased,while CO、HC and smoke at first are decreased and then increased.With the increasing of the interval angle between main and post injection,NOxemission is decreased,CO、HC and fuel consumption rate are increased,while smoke at first is decreased and then increased.Compared with the single injection,NOxand smoke are reduced,but fuel consumption rate is increased with the post-injection.It could be achieved trade-off of emissions and fuel consumption rate with the reasonable post-injection parameters.