高里程出租车的排放控制措施

出租车排放是城市大气污染的重要来源,对高排放出租车加严管理是改善空气质量的有效手段之一.在北京市选取6辆有代表性的高里程汽油出租车,较全面地评估了维护保养、更换三元催化器对出租车油耗和排放的影响,以及三元催化器在更换后的老化情况.研究表明:常规的维护保养可显著改善车辆的燃油经济性,保养后车辆的100 km油耗比原车降低了2%～4%,但对THC和NOx排放的影响很小.原车排放越高,更换三元催化器的减排效果越显著,且更换第一级三元催化器(前三元催化器)和同时更换第一、二级三元催化器(前、后三元催化器)的减排效果差别较小.更换三元催化器后行驶里程约18.5×104 km时,有4辆出租车对CO、THC和NOx的减排比例仍保持在45%、26%和29%的平均水平,说明更换三元催化器后,在约20×104km的行驶里程内对气态污染物能保持较好的减排效果.

Methods for Controlling Emissions from High Mileage Taxis

Taxi emissions are an important source of urban air pollution,so controlling emissions from high emission taxis is critically important for air quality improvement.Six representative high mileage gasoline taxis in Beijing were chosen,and the effects of vehicle maintenance and replacement of the three-way catalytic converters(TWCs) on fuel consumption and emissions were comprehensively assessed.In addition,the deterioration of the TWCs after replacement was also evaluated.The results indicated that common maintenance could significantly improve the fuel efficiency by about 2%-4%,but it had little effect on THC and NOx emissions.When the TWCs were replaced,greater emission reductions occurred for the taxis with higher original emissions.Furthermore,the difference between emission reduction by only replacing the first TWC versus replacing both the first and second TWC was negligible.The average reductions of CO,THC and NOx emissions from the four taxis were 45%,26% and 29%,respectively,even after traveling 185,000 km with the replaced TWCs.This indicated that the replaced TWCs could remain effective for the reduction of gaseous pollutant emissions within 200,000 km.