公交车燃用生物柴油的颗粒物水溶性离子排放

以一辆国Ⅴ柴油公交车为研究对象，在重型底盘测功机上运行中国典型城市公交循环，试验研究了柴油（D100），体积混合比例分别为5%（B5）、10%（B10）和20%（B20）的废食用油制生物柴油-柴油混合燃料的尾气颗粒物水溶性离子（Water soluble ions，WSI）排放特性.结果表明：国Ⅴ柴油公交车尾气颗粒物呈弱酸性；WSI约占颗粒物质量的3%，主要集中在PM_0.5~2.5和PM_2.5~18粒径段，阴离子占WSI总量的72%~79%；废食用油制生物柴油对公交车尾气颗粒WSI种类没有影响；随着废食用油制生物柴油混合比例的增加，公交车尾气颗粒物WSI阴、阳离子浓度、颗粒物酸性整体增大，WSI浓度峰值向小粒径段移动；CaCl₂和NaCl可能是柴油公交车尾气颗粒物Cl^-、Ca²⁺、Na⁺的主要存在形式；控制废食用油制生物柴油硫、Na⁺、Ca²⁺和Cl^-含量，优化缸内燃烧减少NO_x排放，对降低柴油公交车尾气颗粒物WSI排放具有重要意义.

Emission characteristics of water soluble ions in particles from a diesel bus fueled with biodiesel blends

The water soluble ions (WSI) emission characteristic in particles from a China-V bus fueled with biodiesel blends at proportions of 5%, 10% and 20% (v/v) made from waste cooking oil was investigated based on a heavy chassis dynamometer under Chinese city bus cycle. The results show that the particles from this bus presented faintly acid, the WSI mass accounted for about 3% of the total particles, which main distributed in particles with size from 0.5 to 18μm. Among the WSI, the anions weighted for 72%~79%. The biodiesel had no effect on the WSI specials, but the WSI anions emissions and acidity of the particles increased with the biodiesel proportion in the blends, and the peak of WSI concentration shifted to smaller size. The Cl^-、Ca²⁺、Na⁺ might originate from CaCl₂ and NaCl. Controlling the sulfur content, Na⁺, Ca²⁺ as well as Cl^- content in the biodiesel, optimizing the cylinder combustion to reduce NO_x emission were of significance to reduce the WSI emissions in the particles from diesel bus.