预喷射对生物柴油发动机燃烧及排放特性影响研究

Influence of Pilot-injection on Combustion and Emission Characteristics of Biodiesel Engine

研究了不同预喷条件下满足国Ⅴ排放的高压共轨柴油机燃用混合燃料BD20(含80%体积分数的国Ⅴ柴油和20%体积分数的餐饮废油制生物柴油)的燃烧及排放特性。结果表明:采用预喷射后滞燃期有所缩短,燃烧持续期有所增大。相比于预喷间隔,预喷油量对滞燃期及燃烧持续期的影响更为显著;预喷射显著减小了主燃烧的压力升高率,改善了燃烧的剧烈程度,且低负荷取较小预喷间隔、高负荷取较大预喷间隔效果较优;采用预喷射后NOx排放均有所降低,大部分预喷射条件下PM排放有所增加,各负荷均存在着较佳预喷射方案,可以同时改善NOx及PM排放。

The combustion and emission characteristics of State V diesel engine fueled with BD20 blended fuel （80% volume fraction of State V diesel and 20% volume fraction of waste cooking oil biodiesel） were researched under different pilot-injec- tion conditions. The results show that the ignition delay period and the combustion duration becomes shorter and longer respectively after pilot-injection. Compared with pilot-injection interval, the pilot-injection quantity has more significant influence on ignition delay period and combustion duration. The pilot-injection decreases the pressure rise rate of main combustion remarkably and improves the intensity of combustion with better effect when configuring a shorter pilot-injection interval in low load and a larger pilot-injection interval in high load. After applying the pilot-injection, NOx emission decreases, but PM emission increases in most conditions. For each load, there is a better pilot-injection scheme which can improve NOx and PM emission simultaneously.