A species-specific gas sensor and monitor comprising a light source, a sample enclosure or measurement chamber, an optical interface between the light source, the sample and the detection system, electronics that integrate the light source and the detection system, and computational components, such as an onboard microprocessor for calculation of the gas composition and communications between the sensor and the vehicle electronics. The species-specific gas sensor of the present invention can be used to target gases, such as nitric oxide (NO), nitrogen dioxide (NO.sub.2) ammonia (NH.sub.3), and sulfur dioxide (SO.sub.2) which are measurable in the UV spectrum.

An apparatus includes an engine module, an in-cylinder content module, and an engine out NOx module. The engine module is structured to interpret engine in-cylinder data regarding an operating condition within a cylinder of an engine, wherein the engine in-cylinder data includes an engine torque, an engine speed, a rail pressure, and a start-of-injection. The in-cylinder content module is structured to interpret at least one additional in-cylinder data point regarding the operating condition within the cylinder of the engine. The engine out NOx module is structured to determine an engine out NOx amount responsive to the engine in-cylinder data and the at least one additional in-cylinder data point.

Disclosed is a method for control of dosage of a reducing agent into an exhaust stream, which includes: determining at least one sensor signal S.sub.NOx from at least one nitrogen oxides NO.sub.x sensor arranged downstream of at least one of the one or more reduction catalysts as at least one sensor correction value S.sub.NOx_corr, respectively, if: 1) the engine rotates without fuel supply; 2) an exhaust mass flow M′.sub.exh is greater than an exhaust mass flow threshold M′.sub.exh_th; M′.sup.exh>M′.sub.exh_th; and 3) the sensor signal S.sub.NOx has had a value smaller than a sensor signal threshold S.sub.NOx_th; S.sub.NOx<S.sub.NOx_th; during at least a predetermined time period T.sub.con; determining at least one adjusted sensor signal S.sub.NOx_adj based on the at least one sensor signal S.sub.NOx and the at least one sensor correction value S.sub.NOx_corr, respectively; and controlling the dosage of the reducing agent based on the at least one adjusted sensor signal S.sub.NOx_adj.

An exhaust gas treatment system for an internal combustion engine includes an exhaust gas pathway that receives exhaust gas from the engine, a temperature sensor configured to generate a temperature signal associated with a temperature of the exhaust gas at a position along the exhaust gas pathway, and a reductant source. The system also includes first and second injectors in fluid communication with the reductant source. The first and second injectors are configured to inject reductant into the exhaust gas pathway at first and second rates. The system also includes a first treatment element positioned downstream of the first injector and within the exhaust gas pathway, and a controller in communication with the temperature sensor. The controller is configured to receive the temperature signal from the temperature sensor and adjust at least one of the first rate or the second rate based at least in part on the temperature signal.

A deterioration determination apparatus is usable with an ammonia sensor that includes an ammonia element portion that includes, a solid electrolyte, an ammonia electrode, and a reference electrode. The deterioration determining apparatus compares a first evaluation value and a second evaluation value, and determines whether deterioration has occurred in the ammonia element portion of the ammonia sensor at an evaluation time or subsequent to the evaluation time. The first evaluation value is based on a first sensor current obtained when a DC voltage is applied between the ammonia electrode and the reference electrode of the ammonia element portion at an initial time that is during an initial use period of the ammonia sensor. The second evaluation value is based on a second sensor current obtained when the DC voltage is applied between the ammonia electrode and the reference electrode subsequent to the initial period of use of the ammonia sensor.

The present invention relates to a system and method for monitoring the concentrations of various species in exhaust gas expelled from a stationary source. The system comprises an exhaust passage and monitoring apparatus for monitoring exhaust gas, the monitoring apparatus comprising: a sampling tube extending into the exhaust passage for collecting a sample of exhaust gas; a sampling cavity in communication with the sampling tube; and one or more sensors for measuring the concentration of one or more airborne species within the sampling cavity, wherein the monitoring apparatus comprises suction generating apparatus in communication with the sampling cavity for drawing exhaust gas along the sampling tube into the sampling cavity. The invention further relates to a monitoring apparatus for attachment to an exhaust passage of a stationary source and a method of fitting the apparatus to an exhaust passage.

A method of monitoring an SCR catalyst in which an area factor (a) of the SCR catalyst is ascertained by means of an observer. It is concluded that there is a fault in the SCR catalyst when a comparison shows that the area factor (a) has gone below a threshold value (S).

An exhaust gas after-treatment system for an internal combustion engine includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device in communication with exhaust gases from the internal combustion engine and having treated exhaust gas output. An oxides of nitrogen (NOx) sensor is coupled to treated exhaust gases and has a NOx sensor output signal that is NOx and ammonia (NH.sub.3) cross-sensitive. A closed loop observer (CLO) is operatively coupled to receive the NOx sensor output signal and provides a NOx concentration signal to an electronic control unit operatively associated with the exhaust gas after-treatment system and the internal combustion engine. CLO output at least includes an exhaust gas NOx concentration estimate and the ECU is arranged to be operable upon the NOx concentration estimate to control exhaust gas after-treatment system and internal combustion engine to effect an overall reduction in actual NOx concentration with the exhaust gases.

A particular-gas concentration-measuring apparatus measures a particular gas concentration being the concentration of a particular gas in a measurement-object gas. The particular-gas concentration-measuring apparatus comprises a particular-gas concentration derivation unit. The particular-gas concentration derivation unit causes an electromotive-force acquisition unit to acquire an electromotive force and derives a correction value compensating for the difference between a correction-value derivation electromotive force that is the electromotive force and the reference electromotive force at a correction-value derivation time. The correction-value derivation time is a time during which a sensing electrode is exposed to a correction-value derivation gas, the correction-value derivation gas being the measurement-object gas where neither ammonia nor a combustible gas is assumed to be included. The particular-gas concentration derivation unit derives the particular gas concentration using a corrected electromotive force determined by correcting the electromotive force with the correction value.

Technical solutions described herein include an emissions control system for treating exhaust gas in a motor vehicle including an internal combustion engine. The emissions control system includes a model-based controller to control reductant injections into the exhaust gas. Controlling the reductant injections includes determining an amount of NOx and an amount of NH3 at an outlet of the first SCR device, and at an outlet of the second SCR device. The controlling further includes computing an amount of reductants to inject to maintain a first predetermined ratio between the amount of NH3 and the amount of NOx at the outlet of the first SCR device and to maintain a second predetermined ratio between the amount of NH3 and the amount of NOx at the outlet of the second SCR device. Further, the controlling includes sending a command for receipt by the reductant injectors to inject the computed amount of reductants.