Exhaust Mixer Deflector Segmentation for Urea Mixing
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Solution Overview
Problem
Existing exhaust aftertreatment systems face challenges in achieving efficient mixing of exhaust gases and urea solutions while minimizing urea deposit rates and system complexity, particularly in meeting stringent emission and fuel consumption regulations.
Innovation Solution
A mixer design comprising a shell, baffles, a deflector, and an impactor with specific deflecting surfaces and a radial gap, which facilitates efficient mixing of exhaust gases and urea solutions within a limited distance, reducing urea deposit rates and system size, and improving treatment efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a deflector with a spiral surface is provided to increase the mixing stroke, then the mixing uniformity of exhaust gas and urea is improved, but the structure becomes complicated and the temperature of the mixed system is lowered
Solution Approach 1:
The deflector is segmented into multiple deflecting surfaces (first deflecting surface, second deflecting surface, third deflecting surface) that are arranged at different positions and angles. Each surface segment contributes to directing the exhaust gas flow in a specific direction, collectively achieving thorough mixing without requiring a complex spiral structure. This segmentation allows the mixing function to be distributed across simpler geometric surfaces.
Solution Approach 2:
Different regions of the deflector are designed with different local properties - the first deflecting surface faces the first baffle to intercept exhaust gas, while the second and third deflecting surfaces extend from lateral ends at specific angles. This local differentiation optimizes the flow direction control in various zones of the mixing chamber, achieving uniform mixing through localized flow management rather than a uniform spiral structure.
2Stability of the object's composition
If the mixing stroke is increased to improve mixing uniformity, then the mixing efficiency is improved, but the temperature of the mixed system is lowered and urea deposit rate is increased
Solution Approach 1:
The deflector utilizes three-dimensional spatial arrangement with deflecting surfaces extending in multiple directions and angles. The second and third deflecting surfaces extend from lateral ends of the first deflecting surface toward the first baffle at specific angles, creating a three-dimensional flow pattern. This dimensional approach achieves thorough mixing within a compact space, eliminating the need for extended mixing strokes that would cause temperature drop.
3Object-generated harmful factors
If a mixer is provided to treat nitrogen oxides, then the nitrogen oxide emissions are reduced, but the system size increases
Solution Approach 1:
The deflector combines multiple functions into a single component: it directs exhaust gas flow, atomizes the urea liquid, promotes mixing, and controls temperature. By merging these functions into one integrated structure with multiple deflecting surfaces, the mixer achieves effective nitrogen oxide treatment without requiring multiple separate components, thus reducing overall system size.
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 mixer achieves high mixing efficiency, reduces urea deposit rates, and minimizes system size, leading to improved treatment efficiency and fuel economy while ensuring compliance with emission regulations.
Implementation Method 1
the impactor is disposed opposite the injection port for impacting a liquid injected from the injection port into the mixing space
Implementation Method 2
the deflector comprises a first deflecting surface opposite the first baffle, the deflector is disposed adjacent to the impactor
Implementation Method 3
the mixer is located upstream of the SCR catalyst to mix the exhaust gas discharged from the engine with a urea conversion product
Data Source
AI summary
The present disclosure relates to a mixer and an exhaust aftertreatment system comprising the mixer. The mixer comprises a shell, an injection port, a first baffle, a second baffle, a deflector, and an impactor, wherein the first baffle is provided with a gas inlet, the second baffle is provided with a gas outlet, the first baffle and the second baffle are disposed opposite each other, and the first baffle, the second baffle and the shell provide a flow space for an exhaust gas to flow in the mixer; and in the flow space, the first baffle, the shell, the deflector and the impactor provide a mixing space, the deflector comprises a first deflecting surface opposite the first baffle, the deflector is disposed adjacent to the impactor, and the impactor is disposed opposite the injection port for impacting a liquid injected from the injection port into the mixing space. The mixer and the exhaust aftertreatment system have the advantages of a simple structure and a high processing efficiency.