Real life evaluation of the emission reduction potential of a city bus retrofitted with a continuous regenerating trap

A cost effective measure to reduce particulate matter (PM) emissions of city buses is retrofitting with a continuous regenerating trap (CRT). In this paper, the performance of the CRT is evaluated in real life conditions using an on-the-road emission and energy measurement system developed previously in our laboratory.The CRT is found to reduce PM emissions to over 90% thereby also reducing CO and THC to at least 65%. No significant NOx change is detected. The raise in fuel consumption is not significant. The exhaust gas temperature at the CRT is over 250 °C for 70% of the time thus easily fulfilling the manufacturer's demand. The demand for a NOx/PM ratio of 15 is at least realised during 70% of the time.Follow-up measurements after 1 year showed no deterioration of the CRT.