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在一台采用高压共轨喷射系统的多缸柴油机上对3种喷嘴形状各异的喷油器进行了试验。试验采用多种喷射压力,并结合使用废气再循环技术,以获得低的NOx和碳烟排放。研究中采用的喷油器包括6孔喷嘴的、10孔喷嘴的和K系数为3的6孔收敛形喷嘴的。所有3种喷油器具有相同的流量值。所试的所有3种喷油器在各自适当的条件下均有NOx和碳烟减排效果。研究发现,低温燃烧可通过采用高的废气再循环率与晚喷相结合来实现。在传统的喷油定时下,高喷射压力明显减少了碳烟的排放。在推迟的喷射定时(即上止点后5°曲轴转角)下,喷射压力的影响不明显。研究发现,在相同的喷射条件下,与直孔喷嘴相比,收敛形喷嘴会产生更高的碳烟排放量。收敛形喷嘴对NOx排放和燃油消耗率的影响不明显。10孔喷油器中的小喷孔喷嘴可产生较小的燃油滴从而导致更好的雾化。10孔喷油器在宽广的运行条件下似乎具有更好的空气利用率从而有显著的NOx和碳烟减排作用。
In a multi-cylinder diesel engine using a high-pressure common rail injection system, three kinds of injectors with different nozzle shapes were tested. The tests employed a variety of injection pressures combined with exhaust gas recirculation techniques to achieve low NOx and soot emissions. The injector used in the study included a 6-hole nozzle, a 10-hole nozzle, and a 6-hole convergent nozzle with a K-factor of 3. The in- All three injectors have the same flow rate value. All three fuel injectors tested had NOx and soot emission reductions under their respective conditions. The study found that low temperature combustion can be achieved by using high exhaust gas recirculation rates in combination with late-stage spraying. At conventional injection timing, high injection pressure significantly reduces soot emissions. At postponed injection timing (ie 5 ° crank angle after TDC), the effect of injection pressure was not significant. The study found that, under the same injection conditions, the convergent nozzle produces a higher amount of soot emissions compared to straight-bore nozzles. The effect of convergent nozzles on NOx emissions and fuel consumption is not significant. Small orifice nozzles in 10-hole injectors produce smaller droplets of fuel resulting in better atomization. The 10-hole injector appears to have better air utilization under a wide range of operating conditions and hence significant NO x and soot emission reductions.