预混合氢气对柴油机燃烧和排放性能的影响

Influences of Pre-mixed Hydrogen on Diesel Engine Combustion and Emission Performance

针对预混合氢气的柴油机,在AVL Fire软件上建立了计算模型,并与试验结果进行对比,验证模型的准确性。在此基础上改变了喷射策略,对发动机缸内工作过程及相应的燃烧和排放性能进行数值模拟和分析。研究结果表明:随着预混合氢气质量分数的增加,缸内压力和温度升高,NOx排放恶化,Soot排放改善;随着预喷射油量和预喷间隔角的增加,NOx质量分数升高,Soot质量分数降低;随着后喷射喷油量的增加,缸内压力和放热率稍微减小,NOx和Soot质量分数降低;随着后喷间隔角的增加,缸内压力、放热率、NOx和Soot排放均未发生明显变化。

The numerical model for pre-mixed charge hydrogen/diesel engine was built by using AVL FIRE software and was further verified by the experimental results.Based on the modified injection strategy,the in-cylinder working process and the correspondent combustion and emission performance were simulated and analyzed with the model.The results showed that the increased fraction of hydrogen led to the increase of in-cylinder temperature and pressure and NOxemission and the reduction of soot emission.With the increase of pre-injection quantity and interval,the mass fraction of NOx and soot emission increased and decreased respectively.In addition,the in-cylinder pressure and heat release rate decreased and the NOxand soot mass fraction decreased with the increase of post-injection quantity,but they hardly changed with the increase of post-injection interval.