废气再循环对增压二甲醚发动机排放与性能的影响

Experimental Study of Effects of EGR on Emissions and Performance of Turbocharged DME Engine

以增压中冷二甲醚发动机为对象,研究废气再循环(EGR)对发动机动力性、经济性和排放特性的影响。试验结果表明:在宽广的负荷范围内采用EGR可大幅度降低二甲醚发动机的排放;发动机EGR率为4.8%～7.5%时,ESC循环试验中的CO、HC和NOx排放均可满足国-Ⅳ排放标准的限值;采用5.5%～8.7%EGR率后,发动机动力性能稍有下降,但下降的幅度较小,发动机在低转速下动力性能受EGR的影响大于在中、高转速时受到的影响;EGR率为5.5%～8.7%时,发动机中、低负荷下的燃料消耗率基本不变,高负荷工况下燃料消耗率升高1.0%～3.8%。

In a turbocharged intercooled DME engine, the exhaust gas recirculation （EGR） on engine power, fuel economy out. The results show that EGR can significantly reduce emissions experimental investigations on effects of and emission characteristics were carried in broad load range. For the EGR rate of4.8%~7. 5%, CO, HC and NO. emissions can meet China IV emysston stanaaras according to ESC test cycle. For the EGR rate of 5.5%~8.7%, engine power and torque are slightly decreased and the effects of EGR on power characteristics at low speed are larger than those at medium and high speeds. For the EGR rate of 5.5%-8. 7%, EGR affects hardly on specific fuel consumption under medium and low loads, however the specific fuel consumption increases 1.0%-3.8% in high load conditions.