Exhaust emissions measured on euro 1 heavy-duty vehicles
Type de document
CHAPITRE D'OUVRAGE (CO)
Résumé / Abstract
The tail-pipe emission features of 5 heavy-duty vehicles were assessed, following an experimental method. The 5 vehicles, ranging from a 3.5-tonne van to a 40-tonne semi-trailer were selected according to several criteria of representativity. Each model was chosen from a small sample of 5 identical, in-service vehicles, from a short smoke test. The high variability found among vehicle samples in smoke opacity and smoke flow is underlined. It points out the need for testing numerous vehicles to get representative data for each category (van, solo truck, semi-trailer). Specific driving cycles were set up to reproduce the actual operating conditions for each selected vehicle. 8 cycles representing more than 2 hours of driving describe the various uses of each vehicle. Emission measurements were carried out on a chassis dynamometer with the as-received vehicles and mass emissions of CO, C02, HC, NOx and particles were expressed per km. Comparisons with the MEET or COPERT functions defined for the equivalent EURO 1 vehicles show a good consistency in the average speed related trends. Similar comparisons are carried out with data proposed by the Technical University of Graz (in g per kg of fuel). Driving behaviour contribution has also been studied on the basis of the 8 cycles which combine 2 driving behaviours (a smooth and a stressed one) with 4 average speeds. Speed deviation along cycles was found to be a good accountable factor for the emission levels observed. However, the regulated pollutants do not all vary in the same way with driving behaviour. The road gradient contribution (up to 6 %) was also studied at various steady speeds. NOx emissions are easily derived from the gradient value (linear relation), independently of vehicle speed.