乙醇柴油发动机排气颗粒对助溶剂感受性

利用微孔沉积式碰撞采集器和热重分析仪研究柴油机燃用乙醇柴油排放颗粒物的特性,探讨助溶剂生物柴油和正丁醇对乙醇柴油排放颗粒的粒径分布、颗粒组分和挥发氧化性的影响。结果表明,乙醇柴油排放颗粒的粒径分布向小粒径方向移动,与0^#柴油相比,B10E10和N5E10乙醇柴油排放颗粒粒径小于1.0μm的质量分数分别增加14.1%和12.5%;与N5E10乙醇柴油相比,B10E10乙醇柴油排放颗粒在0.18~0.32 μm粒径范围内的质量分数增加3.3%,说明助溶剂种类对该粒径范围内的颗粒的量有影响。与0^#柴油相比,柴油机燃用乙醇柴油排放颗粒物中的有机物组分质量分数增加、碳烟和硫酸盐组分质量分数降低。排放颗粒物在热失重过程中经历失水干燥、可溶性物质氧化和固体碳氧化反应3个阶段,在前2个质量损失过程中,乙醇柴油排放颗粒的失重速率峰值对应的温度与0^#柴油排放颗粒的基本相同;在第3个质量损失过程中,由于助溶剂有助于降低碳烟起燃温度,使乙醇柴油排放颗粒的失重速率峰值对应的温度降低,且N5E10乙醇柴油排放颗粒物该温度的降低更明显;在上述3个质量损失阶段中,乙醇柴油排放颗粒的失重速率均高于0^#柴油排放颗粒。

Sensitivity of Particulates From Diesel Engine Fueled With Ethanol-Diesel Blends to the Cosolvent

 The effects of the cosolvent on the characteristics of the size distribution, composition and vaporization oxidization of the particulates in emission of diesel engine fueled with ethanol-diesel blends were investigated by using micro-orifice uniform deposition impactor(MOUDI) and thermogravimetric analyser. The results showed that the size distribution peak of particulates in emission of diesel engine fueled ethanol-diesel of B10E10 and N5E10 shifted to small size and the mass fractions of the particulate with the size range less than 1.0 μm were increased by 14.1% and 12.5%, respectively, compared to that of diesel engine fueled 0^# diesel. The mass fraction of particulates with the size of 0.18-0.32 μm in particulate emission of the engine fueled with B10E10 was increased by more than 3.3% compared to that with N5E10, meaning that the cosolvent in diesel affected the size distribution in the range of 0.18-0.32 μm of the particles. The mass fraction of soluble organic fraction increased and the mass fractions of the dry soot and sulfate decreased in particulate emission of the engine fueled with ethanol-diesel blends. In the TG process of particulate emission there were three distinct stages, including dehydration, oxidation of soluble organic fraction and oxidation of solid carbon. At the first and second stages, the temperature of the maximum mass loss rate of the particulate from ethanol-diesel was essentially the same as that from 0^# diesel. At the third stage, the maximum oxidation temperature of the particulate from ethanol-diesel, especially from N5E10, was lower than the corresponded temperature of the particulate from 0^# diesel due to that the cosolvent could reduce the ignition temperature. Throughout the stage of DTG, the mass loss rate of particulate from ethanol-diesel was higher than that from 0^# diesel.