Exhaust Flow Directing Device for Reducing Reductant Deposits
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Solution Overview
Problem
Existing exhaust aftertreatment systems for diesel engines face challenges in reducing reductant deposit formation, which affects the reliability and emission control efficiency of selective catalytic reduction (SCR) systems.
Innovation Solution
An exhaust flow directing device is integrated into the exhaust aftertreatment system to efficiently mix exhaust gas and reductant by directing at least a portion of the exhaust flow toward the reductant injector, creating a shear force that reduces reductant deposit formation and minimizes exhaust gas recirculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reductant is injected into the exhaust stream to reduce NOx emissions, then emission control effectiveness is improved, but reductant deposit formation increases
Solution Approach 1:
A flow director device is introduced as an intermediary component between the reductant injector and the exhaust stream. This device redirects exhaust flow to enhance mixing with injected reductant, preventing deposit formation while maintaining emission control effectiveness. The flow director acts as a mediator that optimizes the interaction between exhaust gas and reductant.
Solution Approach 2:
The invention changes the flow dynamics parameters by redirecting exhaust flow patterns through the flow director. By modifying the velocity distribution and flow direction, the system enhances mixing efficiency and prevents reductant deposits without compromising NOx reduction performance.
2Reliability
If reductant is injected into the exhaust stream, then NOx reduction is achieved, but mixing efficiency decreases leading to deposit formation
Solution Approach 1:
The flow director serves as an intermediary that actively enhances mixing by redirecting exhaust flow toward the reductant injection zone. This intermediary device creates favorable flow conditions that improve mixing efficiency while maintaining the chemical reduction process effectiveness.
Solution Approach 2:
The invention utilizes pneumatic principles by leveraging exhaust gas flow dynamics to enhance mixing. The flow director manipulates gas flow patterns, creating shear forces and turbulence that promote efficient mixing between exhaust gas and injected reductant without requiring additional mechanical mixing devices.
3Device complexity
If conventional exhaust flow paths are used, then system simplicity is maintained, but reductant deposit formation occurs
Solution Approach 1:
The flow director divides the exhaust flow into different path segments, creating a first flow path through the device and a second flow path around it. This segmentation allows optimization of mixing zones while maintaining overall system simplicity and avoiding complex multi-component assemblies.
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
The solution effectively reduces reductant deposit formation, enhancing the reliability and emission control capabilities of the exhaust aftertreatment system while maintaining exhaust flow to the SCR catalysts.
Implementation Method 1
creating a shear force that reduces reductant deposit formation
Data Source
Figure 1
Figure 2
Figure 3A~4B
AI summary
System and apparatus are disclosed for reducing reductant deposit formation in an exhaust aftertreatment system. A directing device is provided in the exhaust flow path upstream of a reductant opening into the exhaust flow path. The directing device is configured to direct an exhaust flow toward the reductant opening and around the directing device to effectively mix the exhaust flow with a reductant provided through the reductant opening to reduce the formation of reductant deposits.