Disclosed are a method of determining a correcting logic for a reacting model of an SCR catalyst, a method of correcting parameters of the reacting model of the SCR catalyst and an exhaust system to which the methods are applied. The reacting model of the SCR catalyst is defined by m parameters and has n input variables, where m and n are natural numbers with n smaller than m. The reacting model of the SCR catalyst may be adapted to predict nitrogen oxide (NOx) concentration at a downstream of the SCR catalyst at the least.

A system includes a controller having at least one processor coupled to a memory storing instructions that, when executed by the at least one processor, causes the controller to: receive data indicative of operating conditions of at least one of an engine or of an aftertreatment system; determine, during a first period of time, that an amount of NOx output from the aftertreatment system satisfies a low NOx operating mode condition based on the data indicative of operating conditions; determine, during a second period of time, that operating conditions for a conversion efficiency are present based on the data indicative of the operating conditions of the aftertreatment system; determine that the amount of NOx output from the aftertreatment system satisfies a high NOx operating mode condition; and selectively set an alert based on a retrieved minimum value and a retrieved maximum value of the amount of NOx outputs.

An exhaust gas control apparatus includes a first catalyst, a filter, and an electronic control unit. The electronic control unit is configured to alternately execute lean control and rich control multiple times. The lean control is control for, over a period longer than a period from when a target air-fuel ratio is set to a predetermined lean air-fuel ratio until an air-fuel ratio of exhaust gas flowing out from the first catalyst becomes greater than the stoichiometric air-fuel ratio, setting the target air-fuel ratio to the predetermined lean air-fuel ratio. The rich control is control for, over a period longer than a period from when the target air-fuel ratio is set to a predetermined rich air-fuel ratio until the air-fuel ratio of exhaust gas flowing out from the first catalyst becomes smaller than the stoichiometric air-fuel ratio, setting the target air-fuel ratio to the predetermined rich air-fuel ratio.

An aftertreatment device for reducing NOx, PM, HC, and CO generated by a compression-ignition engine. In this device, lean exhaust air generated in the engine is enriched using a reactor together with an oxygen sorption device according to a target deNOx efficiency value, and heat energy is recovered. The enriched exhaust gas then passes through an oxidation catalyst, where NOx is reduced with CO and HC. PM in the exhaust gas is further trapped in a DPF. To lower energy cost, an heat exchanger is used for more effectively heating the DPF during regeneration, and an exhaust gas compressor positioned upstream from the DPF is employed to control engine back pressure. When exhaust gas temperature is low, to regenerate the DPF with minimum energy consumption, an electrical heater is used to heat dosing fuel before it is mixed with exhaust gas, and a regeneration heating process is then jump-started.

A method is provided for monitoring an emission device coupled to an engine. In one example approach, the method comprises: following a deceleration fuel shut-off duration, indicating degradation of the emission device based on an amount of rich products required to cause a sensor to become richer than a threshold. The amount of rich products required may be correlated to an amount of oxygen stored in the emission device.

A diesel exhaust fluid (DEF) delivery system and method for operating same. The method includes determining, by an electronic processor, an operating pressure, and receiving, from a pressure sensor of the DEF delivery system, a system pressure. The method further includes determining, by the processor, a dosing request and a pressure disturbance based on the dosing request. The method further includes determining, by the processor, a control request based on the system pressure and the operating pressure, and a feed forward control value based on the pressure disturbance. The method further includes generating, by the processor, an adjusted control request based on the control request based and the feed forward control value. The method further includes controlling, by the processor, a dosing valve of the DEF delivery system based on the dosing request, and a pressure adjustment component of the DEF delivery system based on the adjusted control request.

A combined heat and power system for generating power using a hydrogen internal combustion engine and producing usable heat from the exhaust gases of the hydrogen internal combustion engine is described. The system includes a heat exchanger and reduction device, such as a catalytic converter. The heat exchanger may extract heat from the exhaust gases upstream of the catalytic converter and thereby control the heat of exhaust gases provided to the catalytic converter for reduction of exhaust gases. The catalytic converter may use hydrogen as a reducing agent, thereby using the same fuel source for powering the engine and reduction of the exhaust gases rather than separate working fluids. The heat exchanger and/or operating parameters of the system may be controlled to control a temperature of exhaust gases at the catalytic converter and thereby control efficiency of the conversion of exhaust gases.

A method of determining suitability of correction for a control logic of a selective catalytic reduction (SCR) catalyst, may include determining a suitability function of the correction based on a previous error and a current error when the correction has been performed, determining a suitability coefficient based on the suitability function of the correction, determining whether the correction may be suitable based on the number of corrections and the suitability coefficient, and resetting the control logic when the correction may be not suitable.

A control system is arranged to control the heater system; wherein the control system is programmed to heat the exhaust after treatment system based on a setpoint value. The control system comprises a controller having an error input and an output; that outputs a heating power setpoint value that is adjusted by a feedback signal, said adjusted setpoint value provided in parallel to a branch including the heater system and a branch including a dynamic response system. The dynamic response system comprises a dynamic response part and a delay part. A first subtractor subtracts a measured heat output and an output of the dynamic response system; an adder adds an output of the dynamic response part and an output of the first subtractor. A second subtractor subtracts a heating power setpoint from the output of the adder to provide a control error signal for the error input of the controller.

In a method for diagnosing an SCR catalyst system of an internal combustion engine, the SCR catalyst system comprises at least one first SCR catalyst device (20) and at least one second SCR catalyst device (30). A first injection position upstream of the first SCR catalyst device (20) in the form of a first metering device (40) is provided for injecting liquid reducing agent for the SCR catalyst devices (20, 30). A second injection position between the two SCR catalyst devices (20, 30) in the form of a second metering device (50) is furthermore provided. Both SCR catalyst devices (20, 30) are monitored in a differentiated way by means of active and passive diagnostic methods.