| abstract |
An emission control system (18, 118) for injecting oxygen-enriched air into an exhaust system (16, 116) of an engine (10, 110) includes a selectively permeable air separating membrane device (20, 120) that produces the oxygen-enriched air (permeate) as well as nitrogen-enriched air (retentate). The oxygen-enriched air being so produced can be introduced into the exhaust system (16, 116) (a) into an exhaust duct (168) extending from an exhaust manifold (28, 128) of the engine (10, 110), (b) into the exhaust manifold (28, 128) of the engine (10, 110), or (c) into a polluant reducing device (130) that is mounted in line with the exhaust duct (128) of the engine's exhaust system (116). The nitrogen-enriched air being produced by the permeable membrane device (20) can be used to further reduce NOx by being mixed with air being supplied to an intake manifold (12) of the engine (10) or by being introduced into a plasma device (32) to generate monatomic nitrogen that is injected in the exhaust gases to react with NOx in those gases. |