Observation of Particle Oxidation in Diesels: Prospect for Combustion Research and Particulate Control

An experimental study of carbon particle oxidation was performed by seeding the intake air of two diesel engines with activated carbon (<5 μm dia) and measuring the exhaust breakthrough of the seed particles under different engine speeds, loads and equivalence ratios. Engine-out particulate mass emissions in these tests were found to increase only marginally upon introduction of particle-laden intake air. These results agree with the qualitative results of previous investigations and suggest that on-board incineration of exhaust particulate can provide an emissions control route that does not require a particle oxidation process external to the engine.

Particle oxidation under unfueled, motored operation was found to be independent of engine speed (40% breakthrough) over the range 780-2300 rpm suggesting further experiments and the need for model development for particle oxidation in diesels. The technique of seeding solid species into the intake air of motored diesels is presented as an experimental departure point from which particle oxidation in diesels can be investigated distinct from particle formation.