Exhaust Elbow Deflector and Flow Separator for SCR Deposit Reduction
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Solution Overview
Problem
In exhaust aftertreatment systems for internal combustion engines, the injection of reductants like urea into elbow-mounted dosing modules can result in reductant deposits on sidewalls due to upstream exhaust gas flow, leading to erosion and reduced mixing efficiency, especially under high exhaust gas flow conditions.
Innovation Solution
The implementation of an exhaust assisted flow separator and a deflector within the exhaust elbow to divert a portion of the upstream exhaust gas, increasing the velocity and mixing of the reductant while deflecting it away from sidewalls, thereby reducing deposit formation and enhancing evaporation and mixing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reductant is injected into elbow-mounted dosing module, then SCR process can be implemented to reduce NOx emissions, but reductant deposits form on sidewalls due to upstream exhaust gas flow
Solution Approach 1:
The patent extracts and removes a portion of the upstream exhaust gas flow from the main stream using a flow separator. This separated exhaust gas is then redirected to interact with the injected reductant, increasing its velocity and preventing deposit formation on sidewalls while maintaining the SCR process effectiveness.
Solution Approach 2:
The patent introduces an intermediary component (flow separator and deflector) that mediates between the upstream exhaust gas flow and the injected reductant. The flow separator acts as an intermediary to divert and redirect exhaust gas, while the deflector serves as an intermediary to prevent direct contact between high-velocity exhaust gas and sidewalls, thereby eliminating the harmful effect of deposit formation.
2Speed
If upstream exhaust gas flow velocity is high, then exhaust gas can be moved through the system, but reductant is deflected toward sidewalls causing erosion
Solution Approach 1:
The flow separator extracts a portion of the high-velocity upstream exhaust gas from the main flow stream. This separated gas is then used to assist reductant injection, while the remaining main stream continues at high velocity to maintain exhaust system performance without causing sidewall erosion.
Solution Approach 2:
The deflector acts as an intermediary barrier between the high-velocity exhaust gas and the sidewalls. It redirects the exhaust gas flow away from direct contact with sidewalls, preventing erosion while allowing the high-velocity flow to continue through the elbow.
3Device complexity
If reductant is injected directly into exhaust flow, then dosing is simplified, but mixing efficiency is reduced
Solution Approach 1:
The system uses the existing upstream exhaust gas flow to assist in the mixing process. By diverting a portion of the exhaust gas through the flow separator and using it to entrain and accelerate the injected reductant, the system achieves improved mixing efficiency without requiring additional energy input or complex mixing mechanisms.
Solution Approach 2:
The patent employs pneumatic principles by using the kinetic energy of the upstream exhaust gas flow to entrain and accelerate the injected reductant. The flow separator creates a region where exhaust gas velocity is converted into mixing action, enhancing reductant dispersion and evaporation without mechanical mixing devices.
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 significantly reduces reductant deposit generation and growth, improving the uniformity of the gaseous ammonia and exhaust gas mixture, reducing backpressure, and preventing structural issues like weldment erosion.
Implementation Method 1
The exhaust assisted flow separator diverts a portion of the upstream exhaust gas to surround injected reductant and forces the reductant through an opening for increasing mixing and evaporation
Implementation Method 2
The deflector includes a length of material to divert or assist the upstream exhaust gas in flowing around a curvature of the elbow while also reducing and/or substantially preventing the upstream exhaust gas from deflecting the injected reductant toward aftertreatment walls
Implementation Method 3
an SCR system may dose or otherwise introduce the reductant through a dosing module that vaporizes or sprays the reductant into an exhaust pipe of the exhaust system
Data Source
AI summary
An exhaust elbow includes an upstream sidewall defining an upstream portion of the exhaust elbow, a downstream sidewall defining a downstream portion of the exhaust elbow, and a deflector. The upstream portion is configured to receive an upstream exhaust gas. The deflector is coupled to the upstream sidewall of the exhaust elbow upstream and is configured to deflect a portion of the upstream exhaust gas received by the upstream portion of the exhaust elbow away from a region of an interior of the exhaust elbow into which an injected reductant from a dosing module is injected. The deflector may reduce and/or prevent formation of reductant deposits on a downstream sidewall. In some implementations, an exhaust assisted flow separator may also be included to direct a portion of the upstream exhaust gas received by the upstream portion of the exhaust elbow through a dosing opening.