The present disclosure describes methods for evaluating quality of DEF dosed to an EAS including a close coupled SCR unit a downstream SCR unit. A NOx conversion efficiency of the close coupled SCR unit and a NOx conversion efficiency of the downstream SCR unit are used to evaluate quality of DEF. In some embodiments, the NOx conversion efficiency of close coupled SCR unit is used to evaluate quality of DEF. Operation of an EAS using the results of the evaluation of quality of DEF are described.

An exhaust-gas purification system of an internal combustion engine includes an electrically heated catalytic device and a three-way catalytic device. The electrically heated catalytic device includes a first honeycomb base having a large number of honeycomb passages and a first catalyst component that is supported on, by a predetermined thin-film treatment, surfaces that define the honeycomb passages and that contains one or more types of noble metals. The three-way catalytic device includes a second honeycomb base having a large number of honeycomb passages and a second catalyst component that is supported on surfaces defining the honeycomb passages and that contains one or more types of noble metals. The total noble metal content per unit volume of the second honeycomb base is higher than the total noble metal content per unit volume of the first honeycomb base.

A modular exhaust subsystem for purifying an exhaust gas feedstream of a compression-ignition internal combustion engine upstream of a base exhaust aftertreatment system includes a selective catalytic reduction (SCR) catalyst, and a first exhaust gas sensor and a first temperature sensor that are arranged to monitor the SCR catalyst. A reductant delivery system is arranged to inject a reductant upstream of the SCR catalyst. A controller is in communication with an engine-out exhaust gas sensor, a second exhaust gas sensor and a second temperature sensor that are arranged to monitor the base exhaust aftertreatment system. The controller controls the reductant delivery system to inject the reductant into the exhaust gas feedstream upstream of the SCR catalyst based upon inputs from the first and second exhaust gas sensors, the engine-out exhaust gas sensor, and the first and second temperature sensors.

The present disclosure relates to a method for determining urea feeding in an exhaust gas aftertreatment system (100,200), the exhaust gas aftertreatment system (100,200) being connectable to an internal combustion engine (101,201) operating under an engine operating condition, the system (100,200) comprising a first Selective Catalytic Reduction (SCR1) system comprising a first selective reduction catalyst (SCR1c) and a first doser (103,203) configured for feeding urea upstream the SCR1 system, at least one Particulate Filter (PF) downstream the SCR1 system or as a substrate for the SCR1c and a second Selective Catalytic Reduction (SCR2) system downstream the PF, the SCR2 system comprising a second selective reduction catalyst (SCR2c) and a second doser (104,204) configured for feeding urea upstream the SCR2c, the method comprising the steps of estimating the amount of particles in the PF; and determining the amount of urea to be fed by the respective first and second doser (4,5) based on the engine operating condition and such that: a) the amount of particles in the PF is within a predefined particle amount range, and, b) the NOx level of the exhaust gas exiting the SCR2 system is within a predetermined NOx level range. The present disclosure also relates to an exhaust gas aftertreatment system (100,200) and a vehicle comprising the exhaust gas aftertreatment system (100,200), a computer program comprising program code means for performing the steps of the method, a computer readable medium carrying a computer program comprising program code means for performing the steps of the method and a control unit for controlling urea feeding in the exhaust gas aftertreatment system (100,200).

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.

An automotive exhaust aftertreatment system includes a three-way catalyst (TWC) fluidly coupled to an internal combustion engine and a muffler, a selective catalytic reduction (SCR) unit located downstream from the TWC and upstream from the muffler, the SCR unit configured as a NOx catalytic converter and a hydrocarbon (HC) trap, and an electrically heated catalyst (EHC) located downstream from the SCR and upstream from the muffler, the EHC configured as a catalytic converter for the trapped HCs once the HCs are released from the SCR.

An electrical heating unit H for introduction into the exhaust gas system of an internal combustion engine, in particular upstream with respect to an exhaust gas purification unit, for instance a catalytic converter, which for its operation requires a temperature higher than the ambient temperature, comprises a casing (13) and at least one resistance heating element (14) which is designed as a band and is retained inside the casing (13), wherein the at least one heating band (14) is arranged so that it runs in a meandering pattern and with its flat face parallel or substantially parallel to the longitudinal axis of the casing (13). The heating unit H also comprises at least one support structure (19, 19.1) which is arranged on the end face relative to the heating band (14) and mechanically connected to the casing (13) and has slot-shaped heating band bearings (27) to retain the heating band (14) inside the casing (13), into which slot-shaped heating band bearings (27) the heating band (14) engages by an edge portion and via which support structure (19) the heating band (14) is electrically insulated from the casing (13).

An exhaust aftertreatment system and associated method for purifying an exhaust gas feedstream of a lean-burn or other compression-ignition internal combustion engine is described. An instruction set is executable to determine an engine-out NO2 concentration upstream of an oxidation catalyst and determine a first parameter associated with O2 concentration. A consumption of oxygen in the oxidation catalyst due to oxidation reactions is determined, and a concentration of NO2 generated by the oxidation catalyst is determined based upon the consumption of oxygen in the oxidation catalyst. A concentration of NO2 downstream of the oxidation catalyst is determined. A NO2/NOx ratio in the exhaust gas feedstream downstream of the oxidation catalyst is determined based upon the concentration of NO2 downstream of the oxidation catalyst and the NOx concentration measured by the downstream NOx sensor. The oxidation catalyst is evaluated based upon the NO2/NOx ratio.

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.

An aftertreatment system for treating an exhaust gas comprises an exhaust conduit, a preheating oxidation catalyst, a primary oxidation catalyst disposed downstream of the preheating oxidation catalyst, and a selective catalytic reduction system disposed in the exhaust conduit downstream of the primary oxidation catalyst. A controller is configured to determine a temperature of an exhaust gas at an inlet of the selective catalytic reduction system. In response to the temperature being below a threshold temperature, the controller generates a hydrocarbon insertion signal configured to cause hydrocarbons to be inserted into or upstream of the preheating oxidation catalyst so as to increase a temperature of the exhaust gas to above the threshold temperature.