Influence of different configurations of a catalyst and a trap on particulate emission of a diesel passenger car

Abstract

New particulate emission measurements performed on a diesel passenger car to see the influence of different configurations of after-treatment systems are reported. Five combinations of a particle trap and an oxidation catalyst are investigated. These configurations are discussed in view of particulate emission, measured by number and mass. All measurements were carried out at a chassis dynamometer of the EMPA. A diesel passenger car with an IDI engine was operated at four steady state conditions. Exhaust gas was diluted in a standard constant volume sampler (CVS) device (full flow dilution tunnel). Particulate size distributions were measured with a scanning mobility particle sizer (SMPS) and gravimetric measurements were performed according to regulations. Furthermore, measurements without CVS tunnel were done by using external dilution units to see the influence of the sampling method. We used a thermo desorber to distinguish volatile and non-volatile aerosol fractions and we analysed filter samples for determination of organic soluble fraction, water-soluble fraction and sulphur content. Huge differences depending on the configuration of the after-treatment system and load were observed. In general it was found that a large reduction of particulate emission could be obtained by using a particle trap. A catalyst converter has minor effect on particulate emission. Nucleation of new particles was observed under certain conditions depending on configuration and sampling method.