A reductant dosing system includes: an injector; a fixed displacement pump in fluid communication with the injector; a reductant source in fluid communication with the fixed displacement pump; a pressure sensor assembly configured to detect a pressure of reductant in the reductant dosing system; and a controller communicatively coupled to the fixed displacement pump and to the pressure sensor assembly, wherein the controller is configured to calculate a flow rate of the fixed displacement pump based on at least a calibration value determined based on data received from the pressure sensor assembly.

A selective catalytic reduction (SCR) system for treating exhaust gas from a diesel engine is provided, along with a method of assembling such a system. The system comprises a frame, a SCR catalyst contained within a SCR canister, and an ammonia oxidation catalyst contained within an ammonia oxidation canister. Each of the SCR and ammonia oxidation canisters is removably attached to the frame.

Selective catalytic reduction (SCR) systems are known and are generally included in the exhaust systems of diesel engines in order to treat the exhaust gases of such engines. Such systems typically involve the introduction of a diesel exhaust fluid (DEF) into exhaust gas flowing in an exhaust passage of an engine. DEF dosing systems are limited by the amounts of DEF that can be delivered without deposits forming on surfaces of the aftertreatment system. An impaction device is dosed with DEF at a first rate based on a set of characteristics of the SCR system. A second set of characteristics, such as an available storage capacity for DEF, is determined based on a set of criteria, such as a decomposition rate of DEF. Based on the second set of characteristics, the DEF dosing rate is changed to a second rate. The dosing rate is reverted to the first rate after a second set of criteria, e.g. a lower threshold of available storage for DEF, are fulfilled.

A selective catalytic reduction (SCR) system is provided for treating exhaust gas in an exhaust passage. The system comprises a hydrolysis catalyst located in the exhaust passage, and a diesel exhaust fluid (DEF) dosing unit configured to inject DEF onto the hydrolysis catalyst. A SCR catalyst is located in the passage downstream of the hydrolysis catalyst, and a controller controls DEF dosing by the dosing unit. The controller is configured to control the DEF dosing unit such that the DEF is injected at a modulated frequency of less than or equal to 1 Hertz. A method of treating exhaust gas in an exhaust passage using an SCR system is also provided.

A decomposition chamber for an exhaust gas aftertreatment system includes an inlet tube, a selective catalytic reduction (SCR) catalyst member, a mixing collector wall, a distribution cap, and a dividing tube. The inlet tube is configured to receive exhaust gas. The mixing collector wall includes a mixing assembly flow aperture. The distribution cap is coupled to the inlet tube and configured to receive the exhaust gas from the inlet tube. The dividing tube is coupled to the mixing collector wall. The dividing tube separates the distribution cap from the mixing assembly flow aperture. The dividing tube includes a first dividing tube inlet aperture that is configured to receive the exhaust gas from the distribution cap. The dividing tube outlet aperture is configured to provide the exhaust gas to the mixing assembly flow aperture.

The method for suppressing formation of a high-melting-point pipe-clogging substance includes disposing a urea-solution supply pipe (6) configured to supply pressurized air and a urea solution into a pipe through which exhaust gas flows, connecting a urea-solution spray nozzle (7) near a tip of the urea-solution supply pipe (6), providing a mixing section (8) configured to mix the exhaust gas flowing through the pipe and a sprayed urea solution sprayed from the urea-solution spray nozzle (7), circumferentially providing a metal sheet (9) on all or part of an inner wall surface of the pipe in a belt-like manner around the mixing section (8), and forming a hydrolysis catalyst layer (10) configured to promote hydrolysis of urea on an inner surface of the metal sheet (9).

A method for exhaust gas post treatment is provided, comprising the following steps: a) providing a nitrogen oxide-containing raw exhaust gas, b) introducing the nitrogen oxide-containing raw exhaust gas into a catalytic evaporator (1), c) introducing a fuel into the catalytic evaporator (1), whereby a converted fuel is obtained, d) mixing urea with the converted fuel, and e) feeding the mixture obtained after step d) into an exhaust gas post treatment system (8). Alternatively or in addition, a device may be provided for exhaust gas post treatment.

An exhaust system comprising: a NOx storage catalyst; an electric heating element; and a NOx reduction catalyst wherein the heating element is located downstream of the NOx storage catalyst.

A reductant injecting device includes: a honeycomb structure comprising: a pillar shaped honeycomb structure portion having a partition wall that defines a plurality of cells each extending from a fluid inflow end face to a fluid outflow end face; and at least one pair of electrode portions arranged on a side surface of the honeycomb structure portion; an outer cylinder being configured to house the honeycomb structure, the outer cylinder having a carrier gas introduction port on the fluid inflow end face side; a urea sprayer arranged at one end of the outer cylinder; a carrier gas introduction cylinder provided at the carrier gas introduction port of the outer cylinder; and a carrier gas flow rate amplifier provided in the carrier gas introduction cylinder.

An aftertreatment system for treatment of exhaust gases exiting an engine includes a first Selective Catalytic Reduction (SCR) device in fluid communication with the engine. The first SCR device receives the exhaust gases exiting the engine for reducing a first quantity of oxides of nitrogen (NOx) present in the exhaust gases. The aftertreatment system also includes an oxidation catalyst in fluid communication with the first SCR device. The oxidation catalyst receives the exhaust gases exiting the first SCR device for oxidizing ammonia present in the exhaust gases into a second quantity of NOx. The aftertreatment system further includes a second SCR device in fluid communication with the oxidation catalyst. The second SCR device receives the exhaust gases exiting the oxidation catalyst for reducing the second quantity of NOx.