Variable-Position Mixer for Exhaust Gas After-Treatment
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Solution Overview
Problem
Existing exhaust gas after-treatment systems for internal combustion engines face challenges in effectively mixing reductants with exhaust gases to enhance pollutant reduction, particularly in creating sufficient swirling motion and turbulence for efficient NOX conversion in SCR catalysts, while also managing backpressure.
Innovation Solution
A variable-position mixer with pivotable louvers is integrated into the exhaust passage downstream of the injector, allowing for regulation between positions that enhance swirling motion and turbulence or reduce backpressure, utilizing a mechanism with an actuator and multiple link arrangement to control the louver positions, ensuring optimal mixing of reductants like diesel-exhaust-fluid with exhaust gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed-position mixer is used in the exhaust passage, then the structure is simple, but the ability to adapt to different operating conditions and optimize mixing is limited
Solution Approach 1:
The mixer is designed with variable-position louvers that can be adjusted between different angular positions (e.g., first position for enhanced swirling motion, second position for reduced backpressure). This dynamic adjustment capability allows the mixer to adapt to different operating conditions such as varying exhaust gas flow rates, reductant injection rates, and temperature conditions, while the overall structure remains relatively compact and integrated into the exhaust system
2Manufacturing precision
If the mixer position is fixed, then the device complexity is low, but the homogeneity of reductant-exhaust gas mixture cannot be optimized
Solution Approach 1:
The mixer employs variable-position louvers that can be dynamically adjusted to different angular positions to optimize the homogeneity of the reductant-exhaust gas mixture. The louvers can be positioned at a first angle to enhance swirling motion and turbulence for better mixing, or at a second angle to reduce backpressure. This dynamic positioning allows precise control over mixing quality based on operating conditions
Solution Approach 2:
The mixer controls mixing homogeneity by changing the angular position parameter of the louvers. By adjusting the louver angle parameter between different positions, the system can optimize turbulence intensity and mixing efficiency. The variable-position mechanism allows continuous or discrete adjustment of this geometric parameter to achieve optimal mixing conditions
3Productivity
If the mixer intensifies swirling motion and turbulence, then the mixing efficiency improves, but the backpressure in the exhaust passage increases
Solution Approach 1:
The mixer uses dynamically adjustable louvers that can switch between different operational states. At a first position, the louvers are configured to intensify swirling motion and turbulence to enhance mixing efficiency. At a second position, the louvers are adjusted to minimize obstruction to exhaust flow, thereby reducing backpressure. This dynamic capability allows the system to optimize the trade-off between mixing efficiency and backpressure based on real-time operating conditions
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 configuration improves the homogeneity of the exhaust gas-reductant mixture, facilitating rapid light-off and efficient operation of downstream after-treatment devices, such as SCR catalysts, by intensifying swirling motion and minimizing backpressure, thereby enhancing pollutant reduction efficiency.
Implementation Method 1
increase, enhance, or intensify a swirling motion and turbulence in the flow of exhaust gas carried by the exhaust passage to thereby mix the introduced reductant with the flow of exhaust gas
Data Source
AI summary
An exhaust gas flow after-treatment (AT) system includes first AT device and a second AT device in fluid communication with and positioned in the flow of exhaust gas downstream of the first AT device. The AT system also includes an exhaust passage for carrying the flow of exhaust gas from the first AT device to the second AT device and an injector for introducing a reductant into the exhaust passage. The AT system additionally includes a variable-position mixer arranged within the exhaust passage downstream of the injector. Furthermore, the AT system includes a mechanism configured to regulate the variable-position mixer between and inclusive of a first mixer position configured to increase a swirling motion and turbulence in the exhaust gas flow within the exhaust passage to thereby mix the reductant with the exhaust gas flow, and a second mixer position configured to reduce a backpressure generated by the mixer.