Exhaust Gas Mixing Assembly with Segmented Chambers
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Solution Overview
Problem
In compact exhaust systems, there is an inefficiency in mixing exhaust gas with a reactant like a urea/water solution due to condensation and insufficient mixing, leading to deposits and reduced availability for catalytic reactions in SCR catalytic converters.
Innovation Solution
The exhaust gas/reactant mixing arrangement divides the mixing zone into two chambers, with the reactant injected into one chamber, creating flow conditions that support mixing and shielding it from the outside, reducing condensation risks, and using symmetrically arranged openings and guide walls to ensure uniform mixing and prevent direct exhaust gas passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If exhaust gas is guided through a long path in the exhaust gas guide housing to achieve thorough mixing, then mixing quality improves, but pressure loss increases
Solution Approach 1:
The mixing process is segmented into distinct zones: a first mixing zone where exhaust gas and reaction agent initially mix, and a second mixing zone where mixing continues. This segmentation allows the exhaust gas to follow a more direct path through the housing while still achieving thorough mixing across multiple staged regions, reducing overall pressure loss compared to a single long mixing path.
Solution Approach 2:
The patent introduces a vertical dimension to the mixing process by positioning the reaction agent discharge arrangement at a height above the exhaust gas inlet, with exhaust gas flowing horizontally through channels at different elevations. This three-dimensional arrangement allows thorough mixing without requiring an excessively long horizontal path, thereby reducing pressure loss while maintaining mixing quality.
2Reliability
If reaction agent is discharged at a height above the exhaust gas inlet, then backflow into the discharge arrangement is prevented, but mixing efficiency may be reduced
Solution Approach 1:
The reaction agent discharge arrangement is positioned in a vertical dimension above the exhaust gas inlet, creating a height difference that prevents backflow. Simultaneously, the system uses multiple horizontal exhaust gas channels at different elevations that connect to the mixing zones, ensuring that exhaust gas can effectively reach and mix with the discharged reaction agent despite the vertical separation.
Solution Approach 2:
The mixing system is divided into multiple mixing zones (first and second mixing zones) at different positions along the exhaust gas flow path. This segmentation ensures that even though the reaction agent is discharged at a height, thorough mixing occurs across multiple staged regions, maintaining mixing efficiency while preventing backflow through the vertical discharge arrangement positioning.
3Stability of the object's composition
If multiple exhaust gas channels at different heights are used, then thorough mixing is achieved, but device complexity increases
Solution Approach 1:
The exhaust gas guide housing is segmented into multiple horizontal channels at different vertical levels, with each channel serving a specific mixing zone. This segmentation is implemented in a systematic manner where channels connect sequentially through the housing, allowing thorough mixing to be achieved through a structured, modular arrangement rather than a complex random configuration.
Solution Approach 2:
The exhaust gas guide housing structure serves multiple functions simultaneously: it guides exhaust gas through multiple channels, provides structural support for the mixing zones, prevents backflow through its geometric design, and facilitates the discharge of reaction agent. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity despite the multi-channel configuration.
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 arrangement achieves efficient mixing of exhaust gas and reactant across the exhaust gas/reactant mixing arrangement's cross-section, reducing condensation and deposit formation, and enhancing catalytic reaction efficiency in SCR converters, especially at low temperatures and load points.
Implementation Method 1
an exhaust gas channel (30) surrounded by the housing wall (20) and through which exhaust gas flows is formed in the exhaust gas guide housing (18)
Implementation Method 2
a mixing zone (36) formed between an upstream end wall (38) and a downstream end wall (40) arranged downstream with respect to the upstream end wall (38), wherein the mixing zone (36) comprises a first chamber (42) and a second chamber (44)
Implementation Method 3
a reaction agent discharge arrangement (46) carried on the exhaust gas guide housing (18) for discharging reaction agent (R) into the first chamber (42) in a main reaction agent discharge direction (H)
Data Source
Figure 1~2
Figure 3
AI summary
An exhaust gas/reaction agent mixing arrangement for an exhaust system of an internal combustion engine for mixing exhaust gas and reaction agent comprises an exhaust gas guide housing (18) extending in the direction of a housing longitudinal axis (G) with a housing wall (20), wherein an exhaust gas channel (30) surrounded by the housing wall (20) and through which exhaust gas flows is formed in the exhaust gas guide housing (18), a mixing zone (36) formed between an upstream end wall (38) and a downstream end wall (40) arranged downstream with respect to the upstream end wall (38), wherein the mixing zone (36) comprises a first chamber (42) and a second chamber (44), and a reaction agent discharge arrangement (46) carried on the exhaust gas guide housing (18) for discharging reaction agent (R) into the first chamber (42) in a main reaction agent discharge direction (H) oriented substantially along a reaction agent discharge line (L).