EVOLUTION OF POLLUTANT EMISSIONS FROM PAS SENGER CARS DURING COLD STARTS

Evolution of pollutant emissions from passenger cars under cold start conditions. CO, CO2, HC, CH4, NOx and N2O emissions were measured on t en conventional petrol-engined passenger cars, ten vehicles equipped w ith a three-way catalyst, and five diesel-engined vehicles over a grea t number of driving cycles under hot or cold start conditions: two sta ndardized European and American cycles, four hot cycles representative of real-world driving conditions, and three representative mini-cycle s, which were repeated 15 times after a cold-start. Simultaneously, wa ter and oil temperatures were measured to assess engine temperatures. The analysis of the results enabled the follow up of emission and temp erature changes with time for various kinematic types. The limit of ho t temperature, the duration of cold-start emissions (over about 6 km) and excess emission rates under cold start conditions could be thus de termined. These parameters significantly vary a lot according to vehic le technology, driving behaviour and pollutant type. These results sho uld allow an accurate modeling of excess emissions under cold start co nditions.