Comparative measurement of the Efficiency of Catalytic After-Burning Devices on a Heavy-Duty Diesel Engine

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, NO_x 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 NO_x emissions and (3) increase of the total particulate emissions at high load modes.