Roadside NOx and Particle Number PTI Emission testing of Heavy-duty trucks

Abstract

This presentation deals with roadside NOx and particle number measurements of heavy-duty trucks on motorways in Austria. Within three consecutive days, more than 500 vehicles were investigated by using different measurement methods.

Methodology: An initial examination was carried out at the truck stop bevor the scale by means of direct sampling at the tailpipe at idle speed with PTI shortest procedure. Conspicuous vehicles were separately submitted to a full universal short test procedure at high idle speed. For validation purpose additional remote sensing at accelerated pass-by was carried out. Three ultra-compact measuring systems based on the OBM 5.0 were used. The analysis of the pollutants contains the components NOx, NO, CO2, CO, HC, O2, particles number PN and the mean particle size. As important reference for the engine setting the Lambda values were calculated from the exhaust composition. For a sufficient comparability of the different vehicles the measured concentrations were related to the Lambda values.

Result: All measurement methodologies worked satisfying. Significantly high fluctuations of the emission concentrations were observed within the Euro emission classes. This fact could be confirmed from the short-test tailpipe measurements at idle speed and the full universal short test. About 20% of the examined vehicles had remarkably high nitrogen oxide and/or PN emissions. Some high emitting vehicles had concentrations more than 100 times of well-functioning ones.