Study On The Driving Cycle And Emission Characteristics Of Wuhan Light-duty Vehicle

The vehicle exhaust emission problem has been continuously deteriorated along with the rapid increase of urban motor vehicle.It has become the key problem which is urgent to be solved in the field of traffic environment.The development of driving cycle is the basis for measuring and evaluating vehicles road emission and is the precondition to stipulate for the control strategy of urban vehicle.The emerging and decelopment of the portable emissions measurement system (PEMS) technology provides an innovative experimental instrument for the research on vehicle emission controls.In addition,its advantages in terms of convenience,real-time nature, accuracy,and massive data collection capability also provide a bran-new access to the development of vehicle driving cycles.Introducing an on-board emission measurement system,which is consist of a portable emissions measurement system OEM-2100 and a Global Position System,this thesis collected four different types of light-duty vehicles' emission data and velocity data second by second on selected routes in Wuhan.Then the driving characteristics of different road were studied and compared with the standerd driving cycle by analyzing of the speed data.The results showed that there was much difference between the driving condition of light-duty vehicle in Wuhan and standerd driving cycle.Using Matlab program,a 1164s light-duty vehicle's driving cycle of Wuhan based on 12 parameters from speed data of roda tests was synthesized, which may reflect the actual driving condition of Wuhan more properly.The average emission factors on different roads in Wuhan were calculated by analyzing of the emission data from road tests. The results showed that the average emission factors of the four light-duty vehicles distinctly exceed the standerd level of Euro II .According to the comparative analysis,we also understood that travel mileage affects vehicle's emission to some extent.More mileage results in more seriously deterioration and more emission.The emission characteristics of four main emission pollutions NOx, HC, CO and CO₂ were studied by analyzing of the emission factors distribution on speed-acceleration plane, and the causation were discussed combined with their producing mechanism respectively.Further,the relationships between the emission factor and three parameters speed,acceleration and vehicle specific power(VSP) were studied.The results showed that speed and acceleration affect vehicle's emission intensively.The best emission performance came true when its velocity range from 30km/h to 50km/h and acceleration range from -0.5 m/s² to 0.5m/s². The conception of vehicle specific power, which has strong relationship with vehicle emission, provides a reasonable explanation of the relationship between emissions and driving modes in the physical process of the driving. The results showed that the dependence of four main emission pollutions on VSP was better than on velocity and acceleration.