Methods and system are provided to heat a catalyst of an after-treatment system for a vehicle. The after-treatment system comprises a heating module having a plurality of heating elements. Each of the plurality of heating elements is independently operable to provide thermal energy to the catalyst of the after-treatment system. One or more of the heating elements of the heating module are selectively operated to provide heat to the catalyst based on an operational parameter of the after-treatment system.

The present disclosure describes methods for evaluating ammonia storage capacity of a close-coupled SCR unit while remaining compliant with prescribed emissions limits, methods of controlling an emission aftertreatment system including multiple SCR units and emission management systems for a vehicle including an internal combustion engine and an emission aftertreatment system that includes two or more SCR units.

A method of operating an engine includes igniting a combustible mixture in a combustion chamber of the engine, which produces exhaust gases. The exhaust gases are ejected into an exhaust manifold of the engine to create a primary exhaust stream. A portion of the exhaust gases is separated from the primary exhaust stream to create a secondary exhaust stream. Air and fuel are then mixed with the secondary exhaust stream to form a reformer feed mixture. The reformer feed mixture is reacted in a catalytic reformer to create a reformate exhaust stream, which is then mixed with an intake air stream to create a mixed air stream. The mixed air stream is the fed to the combustion chamber of the engine as the combustible mixture.

An aftertreatment system comprises a housing defining a first and a second internal volume fluidly isolated from each other. A first aftertreatment leg extends from the first to the second internal volume and includes an oxidation catalyst and a filter. The oxidation catalyst receives exhaust gas from an inlet conduit and the filter emits exhaust gas into the second internal volume. A second aftertreatment leg extends from the second to the first internal volume and includes at least one SCR catalyst disposed offset from the first aftertreatment leg. A decomposition tube is disposed offset from the SCR catalyst and the oxidation catalyst. The decomposition tube is configured to receive the exhaust gas from the second internal volume and communicate it to the inlet of the at least one SCR catalyst. A reductant injection inlet is defined proximate to the inlet of the decomposition tube for reductant insertion.

A method for predicting urea crystal build-up in an engine system when operating according to an intended drive cycle. The method includes providing data representing engine operational conditions for the internal combustion engine during the intended drive cycle, wherein the data comprises values for at least engine speed and engine torque distributed over a time period representing the intended drive cycle; determining values and time variation for at least one exhaust parameter during the time period of the intended drive cycle when the engine system is operated according to the engine operational condition data; providing a reference relation between values and time variation for the at least one exhaust parameter and an expected urea crystal build-up in the engine system when operating the engine system at different engine operational conditions, predicting urea crystal build-up in the engine system when operating according to the intended drive cycle by comparing the determined values and time variation for the at least one exhaust parameter with the reference relation.

A lean-burn internal combustion engine and an exhaust aftertreatment system having an oxidation catalyst are described. A controller determines a fueling rate and a mass flowrate of the exhaust gas feedstream. An inlet temperature of the exhaust gas feedstream upstream of the oxidation catalyst is determined via the first temperature sensor, and an in-use outlet temperature of the exhaust gas feedstream is determined downstream of the oxidation catalyst via the second temperature sensor. An expected outlet temperature from the oxidation catalyst is determined based upon the inlet temperature, the fueling rate, and the mass flowrate of the exhaust gas feedstream. The oxidation catalyst is evaluated based upon the expected outlet temperature and the in-use outlet temperature.

The present disclosure is directed towards a filter arrangement for a reductant supply system of a selective catalytic reduction system. The reductant supply system comprises a tank and a suction tube mounted at least partially in the tank for receiving reductant liquid from the tank. The filter arrangement comprises a restraining body, a filter at least partially forming a filter chamber, a filter outlet from the filter chamber formed through the restraining body and/or filter and a filter mount mounted to the restraining body and/or filter. The restraining body extends radially outwardly from the filter mount and is configured to restrain the filter such that, under the effect of buoyancy in the tank in use, gas in the filter chamber is directed towards the filter outlet.

Systems and methods for controlling a gasoline urea selective catalytic reductant catalyst are described. In one example, an observer is provided that corrects an estimate of an amount of NH.sub.3 that is stored in a SCR. The amount of NH.sub.3 that is stored in the SCR is a basis for generating additional NH.sub.3 or ceasing generation of NH.sub.3.

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.

Various embodiments of the teachings herein include a method for determining the nitrogen oxide content and/or ammonia content in the exhaust gas of an internal combustion engine with a catalytic converter arranged in an exhaust tract and an exhaust gas sensor downstream of the catalytic converter. In some embodiments, the method comprises: determining an operating state of the internal combustion engine, the operating state indicating either lean operation or rich operation of the internal combustion engine; generating a signal using the exhaust gas sensor; and determining the nitrogen oxide content and/or ammonia content in the exhaust gas at least partially based on the determined operating state of the internal combustion engine and the signal.