Flow Modifier for Exhaust Reagent Mixing
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Solution Overview
Problem
Existing exhaust gas treatment systems face inefficiencies in mixing and distribution of reagents like urea in diesel engines, leading to reduced NOx emission reduction effectiveness due to reagent deposition and corrosion, and high reagent injection pressures causing over-penetration and inefficient use.
Innovation Solution
An exhaust gas treatment system with a flow modifier positioned upstream of the reagent injector, featuring a diverter or louvers to increase exhaust gas velocity and improve mixing, reducing reagent impingement on the conduit inner surface and enhancing reagent distribution within the exhaust stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high reagent injection pressures are used to minimize insufficient atomization, then reagent atomization is improved, but the spray plume over-penetrates into the exhaust stream causing impingement on the exhaust pipe inner surface
Solution Approach 1:
The flow modifier is positioned upstream of the reagent injector to pre-condition the exhaust gas flow before reagent injection. This preliminary action modifies the velocity profile and creates favorable flow conditions that prevent over-penetration of the spray plume, allowing effective atomization at reduced injection pressures without reagent impingement on the exhaust pipe inner surface.
Solution Approach 2:
The flow modifier changes the physical parameters of the exhaust gas flow (velocity distribution, flow direction) in the region where reagent injection occurs. By altering these flow parameters upstream, the system achieves optimal spray distribution and prevents over-penetration without requiring high injection pressures, thereby reducing reagent deposition.
2Productivity
If reagent is injected at high pressure to improve mixing, then atomization is enhanced, but reagent is wasted through over-penetration and impingement
Solution Approach 1:
The flow modifier performs preliminary conditioning of the exhaust gas flow to create optimal conditions for reagent injection. By pre-modifying the flow field upstream, the system achieves effective mixing at lower injection pressures, preventing waste through over-penetration while maintaining high mixing efficiency.
Solution Approach 2:
The flow modifier acts as an intermediary element between the exhaust gas stream and the reagent injector. It mediates the interaction by conditioning the exhaust flow to be more receptive to reagent injection, enabling efficient mixing without the need for high-pressure injection that would cause over-penetration and reagent waste.
3Loss of substance
If reagent injection pressure is reduced to prevent over-penetration, then reagent deposition is minimized, but atomization and mixing become insufficient
Solution Approach 1:
The flow modifier pre-conditionsthe exhaust gas flow upstream of the injector, creating favorable flow conditions that enable effective atomization and mixing even at reduced injection pressures. This preliminary flow modification ensures that lower pressure injection does not result in poor atomization quality.
Solution Approach 2:
The flow modifier changes the exhaust gas flow parameters (velocity profile, flow direction) in the injection region, creating conditions that enhance atomization quality. This allows the system to operate at lower injection pressures while maintaining adequate atomization and mixing performance.
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 significantly reduces reagent deposition by over 50% and enhances mixing, allowing for more efficient NOx emission reduction and extended vehicle range by minimizing reagent usage and preventing corrosion.
Implementation Method 1
The flow modifier includes a diverter for increasing the velocity of the exhaust gas at a predetermined location within the conduit relative to the injected reagent
Implementation Method 2
enhance mixing and distribution of the reagent within the engine exhaust stream
Data Source
AI summary
An exhaust gas treatment system for reducing emissions from an engine includes an exhaust conduit adapted to supply an exhaust stream from the engine to an exhaust treatment device. An injector injects a reagent through an aperture in the conduit into the exhaust stream. A flow modifier is positioned within the exhaust conduit and comprises a plate including a plurality of bores spaced apart from one another and positioned about a periphery of the plate. The plate also includes a plurality of slots positioned in parallel with each other.