经过预处理后柴油机颗粒物氧化活性的变化

为评价常用的通过热重分析方法计算动力学参数的准确性，在不同发动机工况下采集了不同种类的柴油机颗粒物，在N₂氛围中进行了预处理，通过分析颗粒物预处理前后微观形态、结构参数的变化，间接评价预处理过程对颗粒物活性、反应动力学计算结果的影响. 80%负荷采集的原始颗粒和微粒聚集体样品的微观形态由洋葱状变为壳核结构，且原始颗粒的粒径显著减小，100%负荷采集的原始颗粒的微观形态变化不明显；三种颗粒物样品经过预处理后微晶的层间距均大幅度减小，且80%负荷下采集的原始颗粒减小程度最大. 80%负荷下采集的微粒聚集体和100%负荷下的原始颗粒的微晶平均长度略微增大，曲率增加显著，而80%负荷下原始颗粒的微晶长度增加较为显著，曲率略微减小.经过预处理后，颗粒物的氧化活性显著降低，间接表明经过预处理的柴油机颗粒物的动力学参数与原始颗粒物的参数有一定差异. 

Oxidation Reactivity Changes of Diesel Particulate Matter After Being Pre-treated

To evaluate the accuracy of the commonly used method based on thermogravimetric analysis in calculation of the thermal kinetic parameters, particulate matter (PM) was sampled at different engine loads and pre-treated in N₂ atmosphere. Indirect evaluation on the influence of pre-treatment on PM kinetic parameters was made based on the analysis of microstructure morphology and nanostructure parameters. Onion-like structures of raw PM and PM aggregation sampled at 80% engine load converted to core-shell like structures, however, it was almost no change for raw PM sampled at 100% load. The diameter of raw PM sampled at 80% load decreased greatly. The mean lattice fringe separation distance decreased for all the three samples and raw PM sampled at 80% load had the largest decrease. For PM aggregation sampled at 80% load and raw PM sampled at 100% load, the mean fringe length changed slightly and mean fringe tortuosity increased greatly, while it was the opposite for raw PM sampled at 80% load. The analysis indicated indirectly that the thermal kinetic parameters of pre-treated samples was different from raw samples.