EGR对生物柴油/异丁醇混合燃料燃烧与排放的影响

在一台四缸四冲程水冷高压共轨柴油机上研究了生物柴油/异丁醇混合燃料在不同EGR率下的燃烧及排放特性.试验结果表明:随EGR率的升高,缸内压力和放热率峰值降低,燃料滞燃期延长,燃烧持续期先缩短后延长,NO排放与核模态颗粒物数密度降低;当EGR率小于6%时,CO和HC污染物的排放都保持在较低水平.相较于生物柴油,燃用混合燃料降低CO污染物的排放;随异丁醇掺混比例的增加,缸内压力与放热率峰值逐渐升高,CO排放降低,但HC与NO的排放逐渐升高,核模态颗粒物数密度升高,积聚态颗粒物数密度和颗粒物质量浓度有不同程度的下降.

Effects of EGR on Combustion and Emission Characteristics of Biodiesel/Iso-Butanol Blends

The effects of exhaust gas recirculation(EGR)on the combustion and emission characteristics of a fourcylinder,four-storke,water-cooled,DICI engine coupled with biodiesel/iso-butanol blends were investigated.Experimental results show that the peak values of the in-cylinder pressure and heat release rate decreased with the increase of EGR,the ignition delay period was extended,and the combustion duration was shortened first but then extended.The NO emissions and the quantitative concentration of nucleation mode particles decreased.When the EGR rate was less than 6%,CO and HC emissions were kept at a low level.Blended fuels can reduce CO emissions compared with biodiesel.With the increase of iso-butanol blending ratio,the peak values of in-cylinder pressure and heat release rate gradually increased and CO emissions decreased,but HC and CO emissions and the quantitative concentration of nucleation mode particles increased,while the quantitative concentration of accumulation mode particles and the mass concentration of particles decreased to different extents.