Calcul des émissions unitaires de polluants des véhicules utilitaires

To assess pollutant unit emissions for duty vehicles we combine engine emission maps with engine operating conditions as calculated by a vehicle simulation model. The SIVA model takes into account the vehicle characteristics (engine, transmission, etc.) including load, and the characteristics of the route taken (road gradients and curves, speed limits, stops). This model calculates instantaneous operating conditions, in particular the engine torque and speed which in turn enables the calculation of pollutant emissions. CO2, CO, HC, NOx and particulate emissions as well as fuel consumption were calculated for three duty vehicles, a small 3.5-tonnes duty vehicle, a 19-tonnes truck and a 40-tonnes semi-trailer truck. Simulated operating conditions corresponded to highway (a 65-km trip), main road (a 93-km trip) and steady vehicle speed conditions for various values of road gradient from −4% to +6%. Results show the significant influence of vehicle mass on fuel consumption and pollutant emissions, engine technology (injection, aspiration), engine tuning (legislation, regulation), vehicle speed and road gradient. Collecting data on pollutant emissions and data on operating conditions in actual vehicle use are thus of great interest.