Impact of the driving cycle on the NOx and particulate matter exhaust emissions of diesel passenger cars

Abstract

The impact of driving cycle on NOx and particulate matter (PM) exhaust emissions of two different passenger cars equipped with the same Euro3 diesel engine is studied in this work. The driving cycles used are the New European Driving Cycle (NEDC), the 11 and 15 modes Japanese cycles, and three U.S. driving cycles: Federal Test Procedure (FTP-75), US06, and Highway. The obtained results show that NOx and PM emissions increase with vehicle weight, as the engine has to operate to higher speed/load points, to satisfy the energy demand of the cycle. NOx emissions increase when a cycle forces the engine to operate at higher speeds and loads, especially in the case of the heavier vehicle. PM emissions generally increase with engine speed, as the load demand requires a higher fuel/air equivalence ratio, and consequently particulate emissions are higher. The indicator NOx + 10PM is used to classify the severity of each cycle: US06 is the highest pollutant emitter, followed by 11 modes, NEDC, FTP, 15 modes, and finally Highway. A driving cycle indicator is also developed in this work; NOx and NOx + 10PM emissions of both vehicles show a very good correlation with this indicator. © 2008 American Chemical Society.