Performance of a continuous regenerating trap on city buses in real traffic conditions

A lot of effort is done to reduce emissions of city traffic. An important part of pollutants (especially PM and NOx) in cites is emitted by diesel-fueled buses. Possibilities to reduce these emissions are the use of alternative fuels (like CNG) or the use of aftertreatment systems or diesel engines. In this study, the emissions of a diesel bus with CRT (Continuous Regenerating Trap) are measured in real city traffic in Lausanne. Thus, the performance of the CRT can be evaluated in representative driving circumstances. The results of the CRT bus are compared to a lean-burn CNG and an old diesel bus. The CNG and CRT bus have both low emissions. The emissions of CO₂, CO, THC and NOx of the CRT bus are respectively 3, 16, 96 and 28% lower than the CNG bus emissions. Both buses have particle emissions of less than 0.02 g/km. It can be concluded that the CRT has a good performance in real city traffic. Comparison of the CRT bus with an old diesel technology indicates the importance of the technological developments in diesel engines and aftertreatment technology.