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An automatic forced regeneration ceramic trap system with throttling before the trap, using Ce based fuel additives, for installation on light-duty diesel passenger cars is described. The system was installed on two vehicles and tested in the laboratory. The repeatability of the back pressure variation due to the soot accumulation during successive FTP cycles was determined, and the operation period of the system was defined. The operation of the system in both applications was equivalent to about 35 km of urban driving. The filtration efficiency approached 80% in FTP cycle and 90% in ECE and JAPAN 13 mode tests, while gaseous emissions and fuel consumption were practically not affected by the system.

The effect of three oxidation catalysts (Honeycat DEP 290, Engelhard PTX 623, Herapur 20L) and one catalytic trap oxidizer (Johnson Matthey JM 13/II) on the emissions of a RABA (M.A.N. Licensed) heavy-duty diesel engine has been comparatively studied. Tests were conducted according to EPA 13 mode test to measure CO, total HC, NOx and total particulate matter emitted by the engine with and without devices. The test results were also correlated to the total emissions of the Athenian buses through new weighing factors of an “Athenian 13 mode test”. The engine tests for all four devices resulted in: (1) considerable reduction of the engines CO and total HC emissions - being already low (2) practicaly no difference in NOx emissions and (3) increase of the total particulate emissions at high load modes.