喷射定时对柴油机排放和燃烧过程的影响

Effect of Injection Timing on Emissions and Combustion Process of Diesel Engine

以一台重型柴油机为研究对象,在低速低负荷工况下,分析预喷定时和主喷定时对排放及燃烧过程的影响规律。结果表明:在主喷定时、预喷与主喷油量比例一定以及EGR率一定的情况下,随着预喷定时往压缩上止点推迟,NO_x和Soot逐渐上升,HC和CO排放逐渐下降,有效热效率逐渐上升;在预喷定时、预喷与主喷油量比例一定以及EGR率一定的情况下,随着主喷定时推迟,NO_x逐渐下降,Soot排放呈现先上升后下降的趋势,HC和CO排放逐渐上升,有效热效率逐渐下降。

Experimental study on the effects of injection timing, like pre - injection timing and main injection timing, on emissions and combustion process was carried out in low speed and low load conditions of a heavy - duty diesel engine. The results show that the NOx and Soot emissions gradually increased, HC and CO emissions decreased and the thermal efficiency gradually increased as the pre -injection timing postponed to the TDC while the main injection timing ,the fuel ratio of the pre -injection and the main injection and the EGR rate were under the same conditions. And when the pre - injection timing, the fuel ratio of the pre - injection and the main in- jection and the EGR rate were under the same conditions, the NOx emissions would decrease, Soot emissions would first increase and then decrease, HC and CO emissions would increase and the effective thermal efficiency would decrease gradually as the main injection timing was postponed.