预喷正时对柴油发动机燃烧和排放特性的影响

The Influence of Pre-injection Timing on the Combustion and Emission Characteristics of Diesel Engines

文章研究了预喷正时对柴油发动机燃烧和排放特性的影响,通过调整一台高压共轨直列四缸柴油发动机预喷时刻,进行相关台架试验。分析了预喷时刻对压力升高率、瞬时燃烧放热率、有效压力循环变动系数、缸内温度等燃烧特性的影响,以及对超细颗粒物、NOx比排放和大颗粒物数目比排放等排放特性的影响。试验结果表明,随着主预喷间隔的增大,峰值压力升高率降低,瞬时放热率峰值提前,超细颗粒物浓度下降,大颗粒和NOx比排放持续降低。因此可以在不改变柴油机整体结构的前提下,通过调整预喷时刻,有效改善发动机的燃烧性能,减少污染物的排放。

In this paper,the influence of the pre-injection timing on the combustion and emission characteristics of diesel engines is studied,and the relevant bench tests are carried out by adjusting the pre-injection timing of a high-pressure common rail in-line four-cylinder diesel engine.The influence of the pre-injection time on the combustion characteristics such as the pressure rise rate,the instantaneous heat release rate,the effective pressure cycle variation coefficient,the cylinder temperature,etc.,as well as the emission characteristics such as the specific emission of the number of ultrafine particles and large particles,and the specific emission of NOx.The test results show that as the main pre-injection interval increases,the peak pressure rise rate decreases,the instantaneous heat release rate peaks earlier,the ultrafine particle concentration decreases,the brake specific particle number and the brake specific nitrogen oxides continues to decrease.Therefore,the combustion performance of the engine can be improved and the emission of pollutants can be reduced by adjusting the pre-injection time without changing the overall structure of the diesel engine.