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This paper presents a study of the transient behaviour of the turbocharged engine equipped with a diesel particulate trap. The trap is considered to be placed before the turbine, to fully exploit the high regeneration potential of the turbocharged engine. This necessitates some design changes to the exhaust system in front of the turbine, in order to keep a good turbocharger response. The fast temperature response of a light-weight exhaust manifold, partially offsets the effect of the trap thermal inertia. However, the turbocharger lag may deteriorate in some cases, due to the significant modifications produced by the trap dead volume on the pulse turbocharging system operation. This effect varies with trap size and mean pressure drop, and it could necessitate a new turbocharger matching.

The rare occurrence during city driving of the exhaust temperature levels required for ceramic trap regeneration without catalytic aid, seems to be the main reason of delay in wide application of the trap. The use of catalysts seems to be more or less necessary. Study of the catalytic activity during trap regeneration had not been very effective so far. This holds equally true for the case of catalyzed trap as for the case of catalytic fuel additives. The lack of a satisfactory theory for the explanation and prediction of catalytic activity, directed international research and development towards the quest of the optimum catalyst, which could support a very simple and low-cost regeneration system. The new approach to the explanation of catalytic activity presented in this paper, denies the above assumption.

A large sample of the in-use vehicles of greater Athens was tested in order to determine the CO, Total HC, NOx and Particulate emissions of these vehicles. The testings were performed according to ECE 15 specifications in a mobile laboratory specially designed and assembled for this purpose. The test results, led to the quantitative estimation of the total air pollution by road traffic in greater Athens and to the expression of emission factors for all the in-use vehicle fleets.

A shore test for the exhaust gas emission control has been developed. The proposed method estimates quantitatively the exhaust gas emissions (g/km) using only the following variables: engine displacement emission at idle emission at increased idle This method also permits the evaluation of the spark timing and the dwell angle influence on the total emissions of the vehicle. The proposed method can be used to identify vehicles with emissions exceeding the permissible standards and it is also sufficiently effective in identifying vehicles requiring maintenance of the ignition system and/or mixture preparation system.