应用燃气汽车对北京市机动车排放的影响

北京市可用的燃气汽车已达4.9万辆。为评估其影响和为下一步制定政策提供依据,应用修正的M OB ILE 5和PART 5模型估算汽、柴油车的排放系数,并结合国内外测试数据估算燃气汽车的排放系数,进一步计算应用燃气汽车前后的排放量。结果表明,应用单燃料压缩天然气(CNG)车替代柴油公交车的措施最有效,单车削减尾气颗粒物和NOx排放的比例达91%和59%,2003年削减总量约为91 t和1.5 k t,占出租车和公交车使用燃气时排放削减总量的91%和88%;但HC和CO排放增加。今后应加强CNG公交车的维护保养,在发展液化石油气(LPG)汽车时应选用单燃料车。

Impact of gas powered vehicles on vehicular emissions in Beijing

The impact of 49 thousand gas powered vehicles in Beijing was evaluated to assess the current impact of alternative fuels used in transportation on air quality in Beijing.Modified MOBILE5 and PART5 models were used to calculate the emission factors of gasoline and diesel vehicles.The vehicular emissions with and without gas powered vehicles were calculated using domestic and international test data.The results show that the replacement of diesel buses by CNG buses is the most effective way to reduce exhaust particulate matter and NO_x emissions with particulate reductions of 91% and NO_x reductions of 59% for each vehicle.The replacement of diesel buses by CNG buses would reduce particulate emissions by 91 tons and NO_x emissions by 1 500 tons in 2003,which are 91% and 88% of the total emission reductions for gas powered taxies and buses.However,the introduction of gas powered vehicles would increase HC and CO emissions so the vehicles must be carefully maintained and dedicated vehicles should be developed specifically for gas powered systems.