Non-Thermal SCR Catalyst Positioning for Diesel Emissions
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Solution Overview
Problem
Current engine systems face challenges in reducing NOx emissions, particularly at low temperatures, due to the complexity and inefficiency of thermal regeneration methods, which increase fuel consumption, system cost, and environmental impact, while also compromising particulate filter effectiveness and catalyst durability.
Innovation Solution
A non-thermal particle trap regeneration system is implemented, where the SCR catalyst is positioned upstream of the particulate filter, allowing for rapid heating and reducing thermal stress, combined with a sulfur-tolerant SCR catalyst and a passive NOx adsorber to enhance NOx reduction efficiency without the need for high-temperature regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If thermal regeneration methods are used to reduce particulate matter emissions, then particulate matter emissions are reduced, but fuel consumption increases and system complexity increases
Solution Approach 1:
The patent extracts the oxidation catalyst function from the thermal regeneration system and places it upstream before the particulate filter. This allows oxidation of CO and HC to occur separately from the particulate filtration process, enabling passive regeneration without the need for active thermal regeneration systems, thereby reducing fuel consumption and system complexity
Solution Approach 2:
The oxidation catalyst performs preliminary oxidation of CO and HC upstream of the particulate filter. This preliminary action creates the conditions for passive regeneration by producing heat in advance, eliminating the need for subsequent active thermal regeneration and reducing overall fuel consumption
2Reliability
If thermal regeneration is used to maintain particulate filter effectiveness, then filter effectiveness is maintained, but catalyst durability decreases due to thermal stress
Solution Approach 1:
The patent segments the aftertreatment system into distinct functional zones: an oxidation catalyst section upstream for CO and HC oxidation, and a particulate filter section downstream for particle capture. This segmentation allows the oxidation process to occur at lower temperatures separate from the particulate filtration process, reducing thermal stress on the catalyst and extending its durability while maintaining filter effectiveness through passive regeneration
3Productivity
If high exhaust temperature operating cycles are used for thermal regeneration, then regeneration efficiency improves, but NOx emissions increase
Solution Approach 1:
The patent converts the harmful CO and HC emissions into a beneficial heat source through the oxidation catalyst. This heat is used to maintain the particulate filter temperature for passive regeneration without requiring high exhaust temperatures, thereby preventing NOx formation while maintaining regeneration efficiency. The harmful pollutants become the fuel for regeneration
4Object-generated harmful factors
If active thermal regeneration systems are implemented, then particulate matter removal improves, but system cost increases due to additional components
Solution Approach 1:
The oxidation catalyst performs multiple functions: oxidizing CO to CO2, oxidizing unburned hydrocarbons to CO2 and H2O, and providing heat for passive particulate filter regeneration. This multi-functionality eliminates the need for separate active regeneration systems, reducing component count and system cost while maintaining effective particulate matter removal
Solution Approach 2:
The system uses the engine's own exhaust gases containing CO and HC as the fuel source for regeneration. The oxidation catalyst automatically oxidizes these gases when conditions are favorable, providing self-service regeneration without requiring external fuel injection systems, burners, or complex control algorithms, thereby reducing system cost and complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables faster SCR catalyst light-off, reduces catalyst degradation, minimizes the need for Exhaust Gas Recirculation, improves NOx effectiveness, and allows operation on high sulfur fuels, meeting stringent emissions regulations while reducing fuel consumption and system complexity.
Implementation Method 1
A sulfur tolerant SCR catalyst is positioned between the particle trap and the engine
Implementation Method 2
A particle trap is positioned between the engine and the tailpipe
Implementation Method 3
an oxidation catalyst. Since these technologies require elevated operating temperatures typically above 250 degrees Celsius
Implementation Method 4
During active filter regeneration, the exhaust gas temperature can be increased by combusting an additional quantity of fuel in the exhaust system
Data Source
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AI summary
An engine system includes a compression ignition diesel engine connected with an aftertreatment system. A source of diesel fuel, which may have a high sulfur content, is fluidly connected to the engine. The aftertreatment system includes a particle trap fluidly positioned between the engine and the tailpipe, and an SCR catalyst fluidly positioned on the particle trap or between the particle trap and the engine. The SCR catalyst is a sulfur tolerant SCR catalyst. A non-thermal particle trap regeneration system includes a valve fluidly positioned between a particulate volume and an inlet to the particle trap. A reductant system has a doser positioned, possibly in the exhaust manifold, to deliver a reductant into the aftertreatment system upstream from the SCR catalyst.