During the period in which a petrol-driven private car is driven with a cold engine, it uses a richer petrol/air mixture in order to overcome carburation difficulties in the inlet manifold. This results in higher emission. With or without catalytic converters, petrol-driven private vehicles show considerably higher emission during the first 2 to 3 minutes of a journey when the engine is cold. Cold-start proportion, at street level and at national level, of petrol-driven cars was studied. The definition used for cold starting of a petrol-driven private car was that it has been running for less than 2,5 minutes and that the car has been stationary, with the engine switched off, for more than two hours. This applied on condition that the ambient temperature is around 7C. It was concluded that when catalytic converters are installed in all private cars, the total emission of CO and hydrocarbons will drop to about 43 % of the level found when catalytic converters were not installed in any private cars, on condition that the traffic volume remains the same as it is today. At the same time, the distribution of total emission levels when driving with cold and hot engines is 60% and 40%, respectively. This is in spite of the fact that petrol-driven private cars are only driven with cold engines for less than 9% of the time. With regard to the proportion of pollutive emission resulting from 'short' journeys (up to 6 km), especially with a cold engine, it appears that about 34% of the emission will result from short journeys, with a distribution of 27 and 7 per cent points for driving with a cold and hot engine, respectively, when catalytic converters are installed in all private cars. In the effort to limit emission, there is therefore a clear potential for using some other, less polluting, form of transport for short journeys. (AB) (27 refs.)
Koldstartsanalyse. (Cold start analysis)
1994
158 pages
Report
Keine Angabe
Englisch
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