Modelling of cold start emissions for road vehicles


Type de document
Résumé / Abstract
A survey was carried out among a lot of European laboratories. We obtained data concerning 661 vehicles and 15500 measurements (1 measurement corresponds to 1 vehicle, 1 driving cycle and 1 pollutant). The date received was analyzed in order to model cold-start-related excess emissions (defined as the difference in grams per start between cold and hot emissions, for a same cycle) for 4 pollutants (co, c02, hq nox) and fuel consumption as a function of various parameters: technology (diesel, catalyst and conventional cars), average speed, ambient temperature and travelled distance. Data were measured during standardised and representative cycles. Using all these data, we proposed an equation describing the relation between excess emission levels and the above parameters. The obtained data were measured for passenger cars, and an extension to the duty vehicles is envisaged. In a second step the model is extended from a single trip to a whole traffic characterized by a number of parameters such as vehicle flow, average speed and environment conditions, using measured distributions of average speed during cold start conditions versus overall average speed, engine start-up temperature versus ambient temperature, and cold start trip number versus trip length. The proposed final model is part of an emission inventory model.

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