A method and system may be provided to perform a process for controlling NO x emissions of an target engine. In one embodiment of the invention, the process may include determining predicted NO x values based on a model reflecting a predetermined relationship between control parameters and NO x emissions, wherein the control parameters include ambient humidity, manifold pressure, manifold temperature, fuel rate, and engine speed associated with the engine. Further, the process may include adjusting the model based on a determination of whether the predicted NO x values meet a predetermined criteria associated with actual NO x values. The adjusted model may be stored in a memory associated with the engine whereby NO x emissions exhausted from the engine may be reduced based on virtual NO x emission values determined from the adjusted model.

NOx emission-control system using a virtual sensor

A method of selectively catalysing the reduction of NO x in an exhaust gas flowing in an exhaust system of an internal combustion engine comprising a filter ( 40 ) for particulate matter comprising a catalyst capable of selectively catalysing the reduction of NO x with a reducing agent, which method comprising introducing a reducing agent, or a precursor thereof, into the exhaust gas and contacting the resulting gas with the filter ( 40 ).

Selective catalytic reduction

An accurate thermodynamic model of an Active Lean NOx (ALNC) Catalyst is presented. The model takes into account hydrocarbon storage and release mechanisms of the ALNC, as well as the degradation in the ALNC hydrocarbon conversion efficiency due to ageing, and thus provides a more accurate estimate of an exotherm generated by hydrocarbon combustion in the ALNC. The estimated exotherm can them be used to detect system degradation and identify components responsible for the degradation.

Diesel aftertreatment systems

A thermo-hydrolysis reactor (1) for producing ammonia-containing gas by heating an aqueous solution of urea is described. The reactor (1) comprises an elongate vessel (2) having a middle tubular section, an enlarged lower section (4) having an inlet (5) for the urea solution, and an enlarged upper section (3) having an outlet (6) therein for the ammonia-containing gas. The reactor (1) is adapted such that, in use, heat transmitted through the walls of the reactor (1) from an external heat source heats the urea solution causing it to hydrolyse producing the ammonia-containing gas.

Exhaust gas treatment

An exhaust mixer (16) is provided for use in an engine exhaust system (10) downstream from an additive injector (14). The mixer (16) includes eight vanes (20), with four of the vanes (20A) extending from a first side (22) of the mixer (16) and arranged in an equally spaced circumferential array around a central axis (24), and the other four of the vanes (20B) extending from an opposite side (26) of the mixer (16) and arranged opposite from the other four vanes (20A) in an equally spaced circumferential array.

Exhaust Gas Additive/Treatment System and Mixer for Use Therein

Urea is pyrolyzed in a chamber designed to facilitate gasification of the urea by pyrolysis with conversion of urea to ammonia and isocyanic acid (HNCO) with water vapor and carbon dioxide The product gases are introduced into exhaust gases from a lean-burn engine, preferably upstream of a turbocharger The exhaust gases are then contacted with an SCR catalyst

Urea pyrolysis chamber and process for reducing lean-burn engine NOx emissions by selective catalytic reduction

A safe, reliable SCR system for reducing NOx emissions from an internal combustion engine hydrolyzes urea or like reagent under sufficient pressure to assure generation of ammonia, without production of solids that could foul injectors or catalysts. The heat for hydrolysis can be provided by the exhaust or an auxiliary means.

John E. Hofmann

Papers

Urea pyrolysis chamber and process for reducing lean-burn engine NOx emissions by selective catalytic reduction

Reducing no emissions from an engine by on-demand generation of ammonia for selective catalytic reduction