DNTP对柴油机颗粒物热重特性与组织形貌的影响

Effect of DNTP on Thermogravimetric Characteristics and Morphology of Diesel PM

利用热重分析、扫描电镜和透射电镜等技术对直喷式柴油机4种工况下颗粒物(PM)样品进行分析,考察了低温等离子体(DNTP)处理前后样品中元素碳和可挥发物含量、表面形貌和初级粒子组织形式的变化。结果表明:原机PM中元素碳含量随负荷增加逐渐升高,形貌上则从团簇积聚状向层片堆叠状和多孔疏松的海绵状过渡,初级颗粒由堆叠厚度大、分形单一的块状形态逐渐向堆叠厚度小、分形复杂的线条式积聚体形态过渡;DNTP处理后,PM中元素碳含量较原机升高,形貌呈现的规律与原机相似,但在全负荷呈树杈状;初级粒子的组织形式与原机全负荷时获取的PM样品相似,表明DNTP可有效地将PM中粘性较高的可挥发物成分分解。

TGA, SEM and TEM were used to investigate the variation of PM properties before and after the treatment of direct nonthermal plasma, including the content of elemental carbon and volatile fractions, the surface morphology and the accumulation form of primary particles. The results showed that with the increasing of load, the content of elemental carbon grew and the morphology changed from accumulated clusters to folium piles and then to porous sponge, and the accumulation of primary particles changed from simple fractal block with high thickness into complex fractal stripes. After the treatment of DNTP, the content of elemental carbon grew and the morphology variation versus diesel load was similar to that of before treatment but presented dendrite structure at full load. Accumulation form of primary particles was similar with that of untreated PM obtained at full load, indicating the volatile fractions with high viscosity can be decomposed effectively by DNTP.