Engine systems and methods use a dual air injection approach to control exhaust reactions and to maintain temperatures below a maximum limit of exhaust system components during engine enrichment operation conditions. Dual air injectors are disposed in the exhaust system with one upstream from, and another downstream from, the catalytic converter. Providing air injection before and/or after the converter helps convert all HC, CO, and PM emissions while keeping the catalyst temperature below the catalyst protection temperature limit. Air injection quantity may be controlled and diagnosed by monitoring the temperatures before and after the catalytic converter. The catalytic converter may be a three-way catalytic converter for lower cost or a downstream two-way catalytic converter may be added if further emission reduction is necessary.

A mixing conduit for use within an exhaust treatment system of a work vehicle. The mixing conduit is configured to receive engine exhaust and a mixture of engine exhaust and reductant. The mixing conduit includes an outer tube and an inner tube within the outer tube. Each tube extends lengthwise from upstream ends to downstream ends of the inner and outer tubes, respectively. The inner tube includes an exterior surface, and the outer tube includes an interior surface. The inner tube defines an inner flowpath within the inner tube. The outer tube and inner tube also define an outer flowpath radially between the exterior surface of the inner tube and the interior surface of the outer tube. The mixing conduit further includes one or more swirler vanes extending radially between the exterior surface of the inner tube and the interior surface of the outer tube and within the outer flowpath.

A multi-stage mixer includes a multi-stage mixer inlet, a multi-stage mixer outlet, a first flow device, and a second flow device. The multi-stage mixer inlet is configured to receive exhaust gas. The multi-stage mixer outlet is configured to provide the exhaust gas to a catalyst. The first flow device is configured to receive the exhaust gas from the multi-stage mixer inlet and to receive reductant such that the reductant is partially mixed with the exhaust gas within the first flow device. The first flow device includes a plurality of main vanes and a plurality of main vane apertures. The plurality of main vane apertures is interspaced between the plurality of main vanes. The plurality of main vane apertures is configured to receive the exhaust gas and to cooperate with the plurality of main vanes to provide the exhaust gas from the first flow device with a swirl flow.

An exhaust aftertreatment system for an internal combustion engine includes an outer casing defining an exhaust flow path for exhaust gases from the internal combustion engine, a selective catalytic reduction unit provided in the exhaust flow path for reducing nitrogen oxides, a urea dosing device for adding urea to the exhaust flow upstream of the selective catalytic reduction unit, and a rotatable mixer device for mixing the urea with exhaust gases upstream of the selective catalytic reduction unit. The exhaust aftertreatment system further comprises an air inlet valve provided upstream of the mixer device for introducing air into the exhaust flow path, and an electric motor arranged for rotating the mixer device to create a suction of air into the exhaust flow path via the air inlet valve.

Methods, apparatuses, and systems for managing a multiple, and particularly a dual-selective catalyst reduction (SCR), exhaust aftertreatment system according to one or more determined reductant dosing strategies are disclosed. A method includes: receiving, by a controller, data indicative of a catalyst of an aftertreatment system; determining, by the controller, a reductant dosing strategy based on a comparison of the data indicative of the catalyst to a respective threshold; and commanding, by the controller, an amount of reductant dosing based on the determined reductant dosing strategy.

A method for controlling emissions from a power plant having an ammonia injection grid that includes a plurality of ammonia injection points includes the steps of injecting ammonia into a flow of exhaust gas at an injection location, the injection of ammonia defining a spatial distribution of ammonia across an exhaust gas flowpath, measuring at least one parameter of the exhaust gas downstream from the injection location, comparing a measured value for the at least one parameter of the exhaust gas to a threshold value for the at least one parameter and, if the measured value for the at least one parameter exceeds the threshold value for the at least one parameter, automatically modifying the spatial distribution of ammonia injection across the exhaust gas flowpath.

An exhaust treatment system for a work vehicle includes a selective catalytic reduction (SCR) system having an SCR outlet for expelling treated exhaust flow therefrom, a flow conduit in fluid communication with the outlet, an exhaust sensor positioned within the flow conduit downstream of the outlet, and a flow mixer positioned upstream of the exhaust sensor. The flow mixer has an end wall defining sector openings circumferentially extending between first and second sector sides and radially between radially inner and outer sector ends. Moreover, the flow mixer has swirler vanes, where each of the swirler vanes extends circumferentially from the first sector side of a respective one of the sector openings and radially between radially inner and outer vane ends. Particularly, the radially outer vane end of each of the swirler vanes is spaced apart from the radially outer sector end of the respective one of the sector openings.

A selective catalytic reduction (SCR) catalyst is disposed in an exhaust gas system of an internal combustion engine. A reductant injector is coupled to the exhaust gas stream at a position upstream of the SCR catalyst, and first and second NO.sub.x sensors provide NOx measurements upstream of and downstream of the SCR catalyst, respectively. A system and method is disclosed for operating the system to determine a NOx amount and/or a NH3 slip amount downstream of the SCR catalyst by decoupling NOx-NH3 measurements from the output of the second NOx sensor to provide control of the reductant injection amount.

A method for controlling the operation of an exhaust aftertreatment system (EATS) in a vehicle is described. The EATS comprises a main SCR catalyst and a pre-SCR catalyst, a pre-injector arranged upstream the pre-SCR catalyst for providing reductant, a bypass channel fluidly connected to the fluid channel and arranged to bypass the pre-SCR-catalyst and the pre-injector, and a valve configured to control a split of exhaust gases between the pre-SCR catalyst and the bypass channel. The method includes determining the amount of ammonia stored in the pre-SCR catalyst; determining the temperature of the main SCR catalyst; when the ammonia storage in the pre-SCR catalyst is below an ammonia storage threshold and the temperature of the main SCR catalyst is above a temperature threshold, injecting reductant by the pre-injector and controlling the valve to allow a flow of exhaust gases to the pre-SCR catalyst sufficient for transporting the injected reductant to the pre-SCR catalyst for increasing the ammonia storage.

An arrangement for testing or treating a dosing valve of a dosing device of a dosing system in a vehicle includes connecting an electrical test drive to an electrical connector of the dosing device and connecting a dosing tester to a liquid inlet of the dosing device. Thereafter, an outlet valve of the dosing tester is opened to provide liquid under pressure to a liquid inlet of the dosing device. After a first given time, the electrical test drive provides pulses to repeatedly attempt to open the dosing valve. Upon a reduction in liquid level of liquid within the dosing tester in response to opening of the dosing valve, an operator closes the outlet valve of the dosing tester to discontinue the treatment.