Diesel Particulate Filter NOx Catalyst Soot Stabilization
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Solution Overview
Problem
Conventional diesel particulate filter systems require frequent active regeneration and additional fuel consumption to manage soot load density and NOx emissions, leading to inefficiencies and increased fuel consumption.
Innovation Solution
An engine system with a compression ignition engine producing a specific NOx to soot ratio and temperature, coupled with a diesel particulate filter coated only with a NOx reduction catalyst, stabilizes soot load density without active regeneration by oxidizing soot at a rate matching soot supply, leveraging higher NOx levels for efficient oxidation and reducing urea consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active regeneration is performed frequently to maintain low soot load density, then runaway exothermic reactions are prevented, but fuel consumption increases
Solution Approach 1:
The patent converts the harmful high-temperature exhaust gas into a beneficial regeneration agent. By allowing soot to accumulate to higher densities and then utilizing the existing high-temperature exhaust to oxidize the soot, the system transforms what would normally be waste heat into a useful regeneration resource, eliminating the need for additional fuel injection while preventing runaway reactions through controlled timing
Solution Approach 2:
The system implements periodic passive regeneration cycles where soot accumulates during normal operation and is subsequently oxidized during designated regeneration periods. This periodic approach allows soot load density to reach levels that would normally trigger frequent active regeneration, yet through timing the oxidation with high-temperature exhaust passages, the system maintains reliability while avoiding continuous fuel consumption
2Loss of substance
If engine calibration is adjusted to produce less NOx, then urea consumption is reduced, but engine efficiency decreases and fuel consumption increases
Solution Approach 1:
The patent changes the operational parameters of the aftertreatment system by allowing higher NOx to reach the DPF and utilizing this increased NOx concentration to enhance passive regeneration efficiency. By adjusting the regeneration timing and utilizing the natural NOx levels from efficient engine operation, the system reduces urea consumption without requiring the engine to operate at lower efficiency calibration points
Solution Approach 2:
The system allows the engine's own exhaust characteristics (high temperature and natural NOx content) to serve the dual purpose of power generation and aftertreatment regeneration. The exhaust gas that would normally be a waste product is utilized to oxidize soot and reduce NOx through the coated filter, making the system self-sufficient and eliminating the need for additional urea injection or engine calibration compromises
3Use of energy by moving object
If soot load density is increased above conventional limits, then back pressure on the engine is reduced, but runaway exothermic oxidation reactions may occur
Solution Approach 1:
The patent allows the harmful accumulation of soot to higher densities to proceed, recognizing that this creates the conditions for effective passive regeneration. By timing the oxidation process with high-temperature exhaust passages, the system converts what would be a harmful runaway reaction into a controlled beneficial process that maintains filter integrity while enabling higher operating soot densities for improved engine efficiency
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 allows for stable soot load densities above conventional limits without runaway exothermic reactions, improving engine efficiency and reducing fuel and urea consumption by integrating engine operation with aftertreatment system efficiency.
Implementation Method 1
a NOx reduction catalyst coated on an internal surface of the diesel particulate filter
Implementation Method 2
The diesel oxidation catalyst serves to catalyze a reaction between nitrogen oxide in the exhaust with available oxygen to produce nitrogen dioxide
Implementation Method 3
the accumulated soot in the diesel particulate filter
Data Source
AI summary
An engine system includes an electronically controlled compression ignition engine configured to burn diesel fuel to produce an exhaust with a temperature and NOx to soot ratio. An aftertreatment system is fluidly connected to the engine and includes a diesel oxidation catalyst, a reductant supply, and a diesel particulate filter coated with a NOx reduction catalyst but not the diesel oxidation catalyst. A soot load density in the diesel particulate filter is stabilized by oxidizing soot at about a same rate as the compression ignition engine is supplying soot to the aftertreatment system without active regeneration. A NOx reduction reaction is catalyzed by the NOx reduction catalyst on the diesel particulate filter.