气口喷射DMM/柴油混合燃料实现HCCI燃烧

为了促进缸内均匀混合气的形成,将不同比例的DMM/柴油混合燃料通过气口喷射,在单缸发动机上实现了具有超低排放特征的HCCI燃烧方式,考察了混合燃料中DMM的比例、冷却EGR率对HCCI燃烧的转速和负荷范围的影响,以及负荷、冷却EGR率和进气温度对HCCI燃烧的影响.研究表明,由于DMM/柴油混合燃料显著改善了燃料的雾化特性,因此混合燃料能够在较宽的转速和负荷范围内实现HCCI燃烧.此外,由于混合燃料含有很高比例的氧份,因此容许采用较大比例的废气再循环,并且因为冷却的废气再循环推迟了HCCI的着火时刻.通过燃料改性结合外部废气再循环在较大范围内实现了HCCI燃烧.

HCCI combustion using DMM/diesel blend fuels by port-injection

To improve the homogenous fuel/air mixture in the cylinder, different DMM/diesel blend fuels were injected into the intake port, and HCCI combustion was investigated on a single-cylinder engine. The effects of DMM contents in blend fuels and cooled EGR rate on HCCI operating ranges were studied, and the influences of engine loads, cooled EGR rates, and intake charge temperature on HCCI combustion and emissions were also evaluated. Experimental results show that, due to the improvement of atomization and spray for DMM/ diesel blends, the operation ranges of HCCI combustion can be extended to a lower engine speed with high engine load. A large EGR level can be used to control the ignition timing, combustion duration, and NOx emissions for high engine loads. HCCI combustion quality at lower engine loads shows an obvious improvement with the increase of intake charge temperature. As a result, the HCCI operating ranges can be broadened by the fuel reformation combined with external EGR.