A diesel exhaust system includes multiple injectors for providing diesel exhaust fluid to an exhaust to reduce NO.sub.x emissions. Two or more injectors provide DEF to the exhaust system of an engine. In one mode, the injectors alternately inject DEF fluid. In one embodiment, the system includes a NO.sub.x sensor or a NO.sub.x model to assist in determining an amount of DEF that must be provided. In a high DEF output operating mode, the DEF amount for one injector is output at a higher rate than the other injector such that deposits may form. After the injector at the higher rate of injection operates for a selected fraction of time, the other injector provides DEF fluid at the higher rate. Further, the system calculates an estimated developed liquid film mass for each injector output. When the estimated developed liquid film mass is not less than a parameter limit film mass, the system performs ATS regeneration.

The invention concerns a method for controlling an SCR catalytic converter. A first modelled level of ammonia (NH3_mod1) and a second modelled level of ammonia (NH3_mod2) of the SCR catalytic converter are determined from two different models. The second modelled level of ammonia (NH3_mod2) is assessed by comparing it with the first modelled level of ammonia (NH3_mod1).

A catalyst state estimation apparatus includes a first sensor, a memory and a processor. The first sensor is configured to acquire information about a catalyst that removes a toxic substance in an exhaust gas, the first sensor being provided in a main passage into which the exhaust gas flows from an internal combustion engine. The memory is configured to previously store a catalyst state estimation model that includes at least one mathematical model. The processor is configured to estimate a removal performance of the catalyst by applying the information about the catalyst acquired by the first sensor to the catalyst state estimation model.

A method for operating an internal combustion engine with an exhaust gas aftertreatment device has a control system that determines a vector field of corresponding engine operating points (n.sub.Eng.sup.i, M.sub.Eng.sup.i) depending on a predetermined reducing agent-fuel consumption weighting q.sub.FD to be maintained during the operation of the internal combustion engine in order to derive a specific DEF-fuel consumption BSFC.sup.i for each of the engine operating points (n.sub.Eng.sup.i, M.sub.Eng.sup.i). The control system selects the element i.sup.Set from the identified vector field to which a minimum specific DEF-fuel consumption BSFC.sup.Set corresponds as the setpoint engine operating point (n.sub.Eng.sup.Set, M.sub.Eng.sup.Set), wherein the control system specifies a setpoint engine speed n.sub.Eng.sup.Set according to the selected element i.sup.Set and specifies therefrom a setpoint gear ratio r.sup.Set, taking into account a current gearbox output speed n.sub.out.

A process for testing a plurality of components of an exhaust gas aftertreatment system (100) is disclosed, wherein the plurality of components comprises a first SCR catalyst and at least one further SCR catalyst arranged downstream of the first SCR catalyst in the flow direction of exhaust gas to be passed through the exhaust gas aftertreatment system, a first NOx sensor assigned to the first SCR catalyst and at least one further NOx sensor and a first DeNOx element assigned to the first SCR catalyst and at least one further DeNOx element and wherein the process comprises at least the following steps: conditioning the SCR catalysts, testing the NOx sensors, testing the DeNOx systems testing a storage capacity for the reductant of the SCR catalysts.

Apparatuses, systems, and methods are disclosed for emissions control. An emissions monitor module measures at least one pollutant level for an exhaust gas flow produced by a combustion source and treated by a pollution control device. The at least one pollutant level may be controllable based on at least one combustion source operating parameter and at least one pollution control device operating parameter. A control module controls the at least one combustion source operating parameter and the at least one pollution control device operating parameter based on the at least one measured pollutant level.

An auxiliary system with purge control automatically supplies diesel exhaust fluid (DEF) to an onboard DEF tank of a diesel engine to enable prolonged unattended operation. The system includes an auxiliary DEF tank, an auxiliary DEF supply line, a controller, a pump, an air inlet, and a three-way valve configured to switch the pump inlet between the auxiliary DEF tank and air. In response to low-level DEF, the pump delivers DEF through the supply line to replenish the onboard DEF tank. The controller may automatically calculate onboard DEF tank volume based on the delivered volume of DEF, and DEF level data received from an ECM, to enable replenishment control regardless of engine make and model. In response to high-level DEF, engine stoppage, or other system fault, the controller switches the valve to air and runs the pump for a predetermined time to purge DEF from the supply line. The auxiliary system may be skid-mounted, portable, and configured to supply DEF to multiple diesel engines.

A diesel exhaust fluid (DEF) control system includes: a target module configured to determine a target rate of injection of a DEF by a DEF injector; an adjustment module configured to determine an adjustment based on a concentration of urea in the DEF; an adjusting module configured to adjust the target rate based on the adjustment to produce an adjusted rate of injection of the DEF by the DEF injector; and an injector control module configured to control injection of the DEF by the DEF injector based on the adjusted rate.

When an internal combustion engine is driven at a low rate below a certain threshold value, exemplary embodiments as disclosed herein allow and restrict a reductant flow to an injector in repeating allowing cycles and restricting cycles. During the allowing cycles the controller is set to keep the reductant flow as close as possible a determined low point setpoint value. During the restricted cycles the reductant flow is prevented.

A diesel exhaust fluid (DEF) control system includes: a target module configured to determine a target rate of injection of a DEF by a DEF injector; an adjustment module configured to determine an adjustment based on a concentration of urea in the DEF; an adjusting module configured to adjust the target rate based on the adjustment to produce an adjusted rate of injection of the DEF by the DEF injector; and an injector control module configured to control injection of the DEF by the DEF injector based on the adjusted rate.