丁醇/柴油混合燃料对压燃式发动机燃烧及微粒排放特征的影响

Effects of butanol/diesel blends on combustion and particulate emission characteristics of compression ignition engine

在一台高压共轨增压中冷四缸柴油机上试验研究了不同工况下,不同掺混比例的丁醇/柴油混合燃料对发动机燃烧及微粒排放特征的影响。结果表明:随着丁醇掺混比的增加,滞燃期延长,预混合燃烧量增加,燃烧相位滞后,且小负荷工况下的影响更为明显。丁醇/柴油混合燃料可在不增加NOx排放的前提下,显著降低排气烟度及微粒排放,但指示热效率较纯柴油略有降低。发动机燃用丁醇/柴油混合燃料的微粒排放绝大多数为超细微粒,比例超过99%;随着丁醇比例的增大,发动机各粒径段微粒数量浓度均有所下降,大负荷工况更为明显。废气再循环(EGR)的引入使得积聚态微粒和总微粒数量浓度明显增加,丁醇的加入使得混合燃料对EGR的耐受性增强。丁醇/柴油混合燃料结合EGR策略可同时降低发动机的NOx和微粒排放。

The effects of butanol/diesel blends on engine combustion and particulate emission characteristics under different operating conditions and blended ratios were investigated on a four-cylinder,common rail,turbocharged diesel engine.The results indicates that the increase in butanol blended ratio leads to prolonged ignition delay,increased premixed combustion and delayed combustion phase,the effect of which is more significant under low load conditions.Butanol/diesel fuel can dramatically reduce exhaust smoke and particulate emissions without increasing NOx emissions,however,the thermal efficiency is slightly lower than that of pure diesel.Most of the particulate emissions from butanol/diesel blended fuel are ultrafine particles,with a ratio of more than 99%.With the increase in butanol ratio,the number concentration of particles in each particle diameter range decreases,which is more distinctive under high load condition.The concentration of accumulated particles and total particles increase significantly with the introduction of Exhaust Gas Re-circulation(EGR).However,the addition of butanol enhanced the tolerance of the mixed fuel to EGR.Butanol/diesel blend fuel combined with EGR strategy can reduce NOx and particulate emissions simultaneously.