Regulated and unregulated exhaust emissions from nine passenger cars

Nine different cars with latest exhaust gas treatment systems were tested on a chassis dynamometer in the certification cycles MVEG and FTP-75 as well as in two more demanding driving cycles. The cars had different engine concepts, i.e. conventional gasoline engine, gasoline engine with direct fuel injection and diesel engine. While all cars fulfilled the exhaust limits in the certification cycle, some severe exceedances were found in other cycles, especially for carbon monoxide in the case of gasoline engines. High emissions of NOx and here especially nitrogen dioxide from diesel engines and gasoline engines with direct fuel injection are especially interesting from the perspective of air quality due to their relevance for ozone chemistry. Keys-words: exhaust, emissions, gasoline, diesel, ozone. Résumé Emissions de gaz d'échappement régulées et non-régulées de neuf voitures Neuf voitures différentes avec les systèmes les plus modernes de traitement de gaz d'échappement ont été testées sur un banc d'essai à dynamomètre sous les conditions des cycles de certification MVEG et FTP-75 et dans deux cycles de conduite encore plus exigeants. Les véhicules avaient des concepts de propulsion différents, à savoir des moteurs Otto conventionnels, des moteurs Otto à injection directe ainsi que des moteurs Diesel. Dans le cycle de certification, les véhicules étaient conformes aux normes pour les gaz d'échappement, mais dans d'autres cycles de test des dépassements considérables ont été constatés, notamment en ce qui concerne les monoxydes de carbone dans le cas des moteurs Otto. Les émissions élevées en NOx – et ici notamment en NO2 – des véhicules Diesel et des moteurs à injection directe ont une importance particulière du point de vue de la qualité de l'air dû à leur importance pour la chimie de l'ozone. Mots cle: gaz d'èchappement, émissions, essence, Diesel, ozone. Introduction Emissions of passenger cars were first regulated at European level in the early 1970s by the directives 70/220/EEC (gasoline engines) and 72/306/EEC (diesel engines). Thereafter, several directives have sharpened the limits considerably. Today, the EURO3-limits are effective, and most new gasoline cars already fulfill the EURO4-limits, which is not mandatory before the year 2005. Nevertheless, the type approval figures do not necessarily reflect the real world emissions of vehicles because the approval testing cycle MVEG is quite undemanding (Hassel 1994), even though cold start emissions were included for EURO3and EURO4-cars. Therefore it seems to be important to quantify the emissions of modern cars under rather realistic conditions. Furthermore it has to be noted that from the perspectives of air quality and climate not only the regulated compounds CO, NOx, HC and PM play major roles. For example, NO and NO2 are recorded as sum NOx although they play contrary roles in ozone chemistry. Therefore, several in-depth investigations beyond the regulated compounds seem to be necessary (Harrison 1996). In this work, nine different cars were tested on a chassis dynamometer. The cars had different engine concepts, i.e. conventional gasoline engine, gasoline engine with direct fuel injection and diesel engine. Besides the well-known European and American driving cycles MVEG and FTP-75 which are used in type approvals, all cars were tested also in the ”Autobahn-cycle”, which represents the driving on German highways, and in the ”MOBINET-cycle” which represents driving in the city of Munich. O2, CO, CO2, N2O, NO, NO2, HC, fuel consumption and air mass were recorded on a second-by-second basis. A brief overview of the literature was recently given by the authors (Mittermaier 2003). 1 Experimental Vehicles and driving conditions The measuring program included eight different cars of the model years 2000 and later which were compliant with EURO3, EURO4, D3 or D4-exhaust regulation standard. For reasons of comparison to older cars, one EURO2 car (model year 1996) was tested either. Three cars had conventional gasoline engines (spark ignition, SI), three cars had SI-engines with direct fuel injection (SI-DI) and three cars had diesel engines (compression ignition, CI) with direct injection. All SI-engines had three-way-catalysts; the diesel engines were equipped with oxidative catalytic converters. For details see Table 1. n° Name Engine type Capacity [cm3] Power [kW] Model Year Mileage [km] Exhaust limit Source 1 Ford Mondeo SI 1796 85 2000 6.100 D4 FZ Jülich 2 VW Golf IV SI 1984 85 2000 83.600 D4 FZ Jülich 3 Ford KA SI 1299 44 2001 53.400 D4 car rental 4 VW Polo FSI SI-DI 1390 63 2002 5.900 EURO4 Volkswagen AG 5 Mitsubishi GDI Space Star SI-DI 1834 9