机动车排放车载实验及模型模拟研究

Study on On-board Measurements and Modeling of Vehicular Emissions

研究机动车的排放特征及获得排放因子 ,是建立机动车排放清单和制定相应控制策略的基础 ,而路上的机动车排放车载测试被认为是实验室台架测试的一个重要补充 .本研究利用AVLDiGas 4 0 0 0light五气分析仪 ,在澳门典型路段上对 7辆汽油轿车样本开展了尾气排放车载实验 .研究发现安装电喷加三元催化转化系统的车辆 (以下称电喷车 )在气态污染物排放上比旧的化油器车有显著降低 ,化油器车HC、CO和NO排放的体积浓度平均值分别为 2 2 7× 10 -6、1 5 7%和 14 77× 10 -6,而电喷车则分别为 33× 10 -6、0 2 1%和 131× 10 -6,约是前者的 1/11～ 1/7.但电喷车在冷启动阶段会出现高排放 ;对电喷车的CO和NO排放浓度做算术平均 ,其绝对值主要由出现频率少的高浓度值所贡献 .研究进一步估算了汽油轿车的排放因子 ,同时利用MOBILE5模型计算了澳门 2 0 0 0年汽油轿车的平均排放因子 ,模型计算值和实验数据估算结果的比值在 5 9%～ 139%之间 ,如果仅比较年平均排放因子 ,这个比值则在 6 8%～ 132 %之间 .结果表明 ,车辆采用电喷加催化转化系统 ,对控制污染物排放的作用显著 ,但催化设备存在冷启动时起燃缓慢的问题 ;对电喷车的技术改进 ,减少其在行驶过程中出现高浓度的污染物排放 ,将能进一步大大降低平均排放水平 ;

It's a basic work to study the characteristics of vehicular emissions and give emission factors for development of vehicular emission inventory and decision-making of the control strategies. On-board emission measurements of on-road vehicles are regarded as important complementary to emission laboratory dynamometer tests. On-board exhaust emission measurements were conducted on seven samples of gasoline cars in a typical road in Macao, using AVL DiGas 4000 light five-gas analyzer. It was found that there was an obvious reduction of gaseous pollutant emissions from cars equipped with electronic fuel injection and three-way catalytic converter system (referred to as EFI cars in the following), compared to old carburetor cars. The average volume concentrations of CO, HC and NO of carburetor cars were 227×10 -6,1.57% and 1477×10 -6, respectively, while those of EFI cars were 33×10 -6,0.21% and 131×10 -6, which were about 1/11 through 1/7 of the former. However, there were high emissions during the cold start of EFI cars. The arithmetical mean concentrations of CO and NO emissions of EFI cars were calculated and their absolute values were predominantly contributed by high concentrations with low frequency. Furthermore, the emission factors of gasoline cars were estimated by test data, and at the same time, MOBILE5 model was used to calculate average emission factors of gasoline cars in Macao in 2000. The ratios between the results calculated by model and estimated by experiment data were in the range of 59%～139%, which would narrow into 68%～132% if only annual average emission factors were compared. The results suggest that EFI+TWC systems equipped in vehicles have good effect on the emission reduction, but catalytic converters are not activated during the cold start. Technical improvement of EFI cars, which could reduce the occurrence of high emissions with low frequency during the operation, would decrease their average level on exhaust emissions a lot. Furthermore, it's reliable that the emission factors of gasoline cars in Macao calculated by modified MOBILE5 model.