重型柴油车PM2.5和碳氢化合物的排放特征

采用车载排放试验对国Ⅱ、国Ⅲ、国Ⅳ重型柴油车尾气在实际道路排放的PM2.5和碳氢化合物进行样品采集,采用电感耦合等离子体质谱技术、离子色谱仪和碳质分析仪对PM2.5各组分进行测试分析,采用五气分析仪对HC进行在线分析.结果表明,重型柴油车PM2.5和HC的排放因子分别为(0.22±0.12) g/km和(0.57±0.45) g/km,且排放因子随机动车排放标准的提高呈明显下降趋势.EC和OC是机动车尾气PM2.5的主要组分,分别占总质量百分比的38.87%~42.87%和16.22%~19.96%;水溶性离子中含量较为丰富的组分主要是SO42-、NH4+和NO3-,分别占总PM2.5质量百分比的7.64%~8.85%、2.22%~3.97%、1.91%~2.73%;元素中含量较高的组分为S、Na、Ca、Fe、和Al;PM2.5和HC的排放因子随车速的增加均呈下降趋势.

Characteristics of PM2.5 and hydrocarbon emitted from heavy-duty diesel vehicle

The PM2.5 and hydrocarbon (HC) samples emitted from heavy-duty diesel vehicles including Euro Ⅱ, Euro Ⅲ and Euro Ⅳ technologies were collected by on-board emission measurements. The PM2.5 chemical compositions were determined by inductively coupled plasma mass spectrometry, ion chromatograph, and the thermal/optical carbon analyzer. HC was analyzed online by five-gas analyzer. Results demonstrated that the emission factors of PM2.5 and HC were (0.22±0.12) g/km and (0.57±0.45) g/km, respectively. Emission reductions of PM2.5 and HC had been achieved as the control technology become more rigorous. EC and OC were the major components of PM2.5, accounting for 38.87%~42.87% and 16.22%~19.96% of the total PM2.5 mass, respectively. The abundance species of water soluble ions were SO42-, NH4+, and NO3-, accounting for 7.64%~8.85%, 2.22%~3.97%, 1.91%~2.73%, respectively. The abundance species of elements were S, Na, Ca, Fe, and Al. It was also found that PM2.5 and HC emission factors were dropped with the increase of the speed.