Abstract: An aftertreatment system (100) includes a decomposition chamber (108), a reductant pump (120), a first dosing module (110), a second dosing module (112), and a controller (133). The first dosing module (110) is coupled to the decomposition chamber (108) and configured to receive reductant from the reductant pump (120). The second dosing module (112) is coupled to the decomposition chamber (108) and configured to receive reductant from the reductant pump (120) independent of the first dosing module (110). The controller (133) is communicatively coupled to the first dosing module (110) and the second dosing module (112). The controller (133) is configured to independently control a first volumetric flow rate of reductant provided from the first dosing module (110) into the decomposition chamber (108) and a second volumetric flow rate of reductant provided from the second dosing module (112) into the decomposition chamber (108).

Abstract: Systems and methods described herein relate to generating ammonia from engine exhaust instead of or in addition to using on-board storage tank(s) and/or doser(s) to provide the necessary chemical reagents for purification of the exhaust stream. Systems and methods for generating ammonia and/or hydrogen from engine exhaust in exhaust aftertreatment systems under ambient conditions comprise at least one water-gas shift (WGS) catalyst and at least one ammonia synthesis catalyst (AMS catalyst) positioned downstream of the WGS catalyst. The WGS catalyst is configured, using the engine exhaust gas as an input, to generate hydrogen used by the AMS catalyst as inputs to generate ammonia and/or hydrogen. The ammonia and/or hydrogen thus generated are used downstream in ammonia- and/or hydrogen-based selective catalytic reduction catalysts (SCR).

Abstract: A turbocharger system comprises a first relatively small high-pressure (HP) turbocharger and a second relatively large low pressure (LP) turbocharger. The turbine of the LP turbocharger is connected in series downstream of the turbine of the HP turbocharger in a first exhaust gas passage. An exhaust bypass flow passage provides a bypass flow path around the HP turbine. A rotary valve is located at a junction of the bypass flow passage and a first exhaust gas flow passage. The rotary valve comprises a valve rotor which is rotatable to selectively permit or block flow to the LP turbine from either the first exhaust gas passage or the bypass gas passage.