Abstract: The present invention provides methods and apparatus for injecting fluid, such as an aqueous urea solution, into an exhaust stream in order to reduce oxides of nitrogen (NOx) emissions from diesel engine exhaust. The present invention uses mechanical spill return atomization techniques to produce droplets having an average size of approximately 50 ?m SMD or smaller. This size range is appropriate to allow urea to react into ammonia within the residence time associated with an on-road diesel engine. This effect is achieved through the use of a whirl plate having a plurality of whirl slots surrounding an exit orifice of the injector, which produce a high velocity rotating flow in the whirl chamber. When the rotating flow of fluid is passed through the exit orifice into an exhaust stream, atomization occurs from a combination of centrifugal force and shearing of the fluid by air as it jets into the exhaust stream.

Abstract: The present invention provides methods and apparatus for injecting fluid, such as an aqueous urea solution, into an exhaust stream in order to reduce oxides of nitrogen (NOx) emissions from diesel engine exhaust The present invention uses mechanical spill return atomization techniques to produce droplets approximately 50 ?m SMD (Sauter mean diameter) or smaller. This size range is appropriate to allow urea to react into ammonia within the residence time associated with an on-road diesel engine. This effect is achieved through the use of a whirl plate having a plurality of whirl slots surrounding an exit orifice of the injector, which produce a high velocity rotating flow in the whirl chamber. When the rotating flow of fluid is passed through the exit orifice into an exhaust stream, atomization occurs from a combination of centrifugal force and shearing of the fluid by air as it jets into the exhaust stream.

Abstract: The present invention provides methods and apparatus for injecting fluid, such as an aqueous urea solution, into an exhaust stream in order to reduce oxides of nitrogen (NOx) emissions from diesel engine exhaust The present invention uses mechanical spill return atomization techniques to produce droplets approximately 50 ?m SMD (Sauter mean diameter) or smaller. This size range is appropriate to allow urea to react into ammonia within the residence time associated with an on-road diesel engine. This effect is achieved through the use of a whirl plate having a plurality of whirl slots surrounding an exit orifice of the injector, which produce a high velocity rotating flow in the whirl chamber. When the rotating flow of fluid is passed through the exit orifice into an exhaust stream, atomization occurs from a combination of centrifugal force and shearing of the fluid by air as it jets into the exhaust stream.