Studies On Vehicle Emission Factor In Xi'an City Under MOBILE6.2 Mobile Source Emission Factor Model

The MOBILE6.2 mobile source emission factor model developed by USEPA is applyed in calculating vehicle composite emission factor of Xi'an, Scenario analysis is used in testing input parameters's sensitivity that affects 5 emissions factors VOC, NOx, CO, PM and CO₂. Sensitivity analysis shows that: different parameter has different affection,for 5 emissions factors, choosing the proper calandar year is in the leading place;registration distribution,diseal fractions, mileage accumulation, vmt fraction etc. are in the next place, CO₂ only is affected by vehicle fuel economy datas;2 commands, 7 commands, 12 commands, 13 commands and 14 commands are sensitive to CO₂, PM, NOx, CO and VOC, respectively. There is an obvious rule that the changing trends between LDGV's and All fleet are idential.Meanwhile the sensitive parameters table and a simple input commands document are given, according to the local vehicle characteristic of Xi'an, seven kinds of datas that external condition commands, vehicle fleet characteristic commands, activity commands, state programs, fuel commands alternative emission regulations and control measures are collected, aftersome parts of value and datas are revised, the vehicle composite emmision factor in 1996 and 2005 are outputed, it shows that: the VOC, CO, NOx and PM decreased 28%,29%,15% and 43%, respectively,from 1996 to 2005. On the contrary, the total emissions are increased, except PM increased about 41%, VOC, CO and NOx are all increased more than 50%.The compare between road tunnel testing and the simulant outputs show: the values of VOC, CO from the road tunnel testing and the model output are similarity, The value of NOx from the model are almost a factor of 2 of the testing datas.How to correspond the relationship among the different governmental department and prompe the datas sharement and communiation is the first problom that should be solved inapplying the MOB1LE6.2 model. Last the papar gives a management sketch in order to manage vehicle pollution, and suggests that creating the vehicle management system under the frame as soon as possible.There is no model to caculate the emission factor from the vehicle source in China, so using the USEPA developed MOBILE6.2 model is a good way to caculate the vehicle composite emmision factor.