Variability in Gram per Gallon Vehicle Emission Factors with Engine Load and Among Driving Cycles

摘要

Fuel-based emission factors vary substantially with engine load for NO_x and, to a lesser extent, for HC and CO for the tested vehicle. Similarly, there is more variability in route average fuel-based emission factors for NO_x than HC and CO. Whereas the modal NO_x emission factors vary by a factor of 7.9, the route averages vary by 40 percent. However, a site-specific emission factor such as could be observed at a hypothetical RSD site could differ from the route average by as much as 87%, leading to a substantial overestimate if used for an area-wide fuel based inventory. Because these results are based on only one vehicle, the results are merely illustrative. As part of ongoing work, additional vehicles will be measured and analyzed to develop more representative findings.