Acute Angle Reactant Injection for Exhaust Mixing
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Solution Overview
Problem
Existing exhaust systems for internal combustion engines face challenges in efficiently evaporating and mixing reactants, such as urea/water, with exhaust gas to effectively reduce nitrogen oxide emissions, particularly under low temperature conditions or low load operations.
Innovation Solution
The exhaust system incorporates a reactant injection arrangement where the main reactant injection direction is at an acute angle to the main exhaust gas flow direction, combined with a reactant collecting arrangement featuring parallel, wettable surfaces that can be heated by the exhaust gas for efficient evaporation and mixing, and are designed to minimize flow impairment by extending in the direction of the exhaust gas flow and being curved to redirect the gas stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the reactant is injected perpendicular to the exhaust gas flow direction, then the reactant can be injected directly into the exhaust gas stream, but the reactant does not efficiently contact the exhaust gas and mixing is poor
Solution Approach 1:
The patent changes the injection direction from perpendicular (one dimension) to acute angle (another dimension) relative to the exhaust gas flow, allowing the reactant jet to penetrate deeper into the flow and create better mixing through oblique impingement and turbulence generation
2Productivity
If the reactant injection direction is parallel to the exhaust gas flow direction, then the reactant is carried along by the flow, but the reactant does not disperse properly and mixing is insufficient
Solution Approach 1:
The patent introduces an acute angle between injection and flow directions, creating a two-dimensional interaction that promotes both axial penetration and radial dispersion, improving mixing while maintaining structural simplicity
3Productivity
If the reactant is injected at a large angle to the exhaust gas flow, then better mixing is achieved, but significant flow impairment occurs in the exhaust gas channel
Solution Approach 1:
The patent optimizes the injection angle parameter to an acute angle range, balancing mixing efficiency and flow impairment. This intermediate angle provides sufficient transverse component for mixing while maintaining adequate axial component to minimize flow resistance
Solution Approach 2:
The patent uses a controlled acute angle that provides just enough deviation from parallel flow to achieve adequate mixing, without excessive angle that would cause significant flow impairment. The solution finds the optimal partial action point
4Productivity
If the reactant collecting surfaces are arranged transversely to the exhaust gas flow, then more surface area is exposed to reactant, but the exhaust gas flow is significantly impeded
Solution Approach 1:
The patent changes the orientation parameter of the collecting surfaces from transverse to acute angle relative to the exhaust gas flow, reducing flow resistance while maintaining adequate reactant exposure through the oblique configuration
5Productivity
If multiple reactant collecting surface elements are used to increase total surface area, then reactant evaporation is improved, but the installation space requirement increases
Solution Approach 1:
The patent arranges multiple reactant collecting surface elements in a nested configuration where smaller elements are positioned within or alongside larger elements, maximizing the total surface area for reactant evaporation within a compact installation space
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 ensures uniform reactant evaporation and mixing across the exhaust gas flow channel, preventing reactant impact on cold surfaces and enhancing the mixing of reactant with exhaust gas, thereby improving the efficiency of selective catalytic reduction downstream, especially during cold starts or low load operations, and meeting stringent emission regulations.
Implementation Method 1
The reactant-wettable reactant collection surfaces located in the exhaust gas flow can be heated by the exhaust gas itself, thus assisting the evaporation of the reactant impinging upon or wetting them
Implementation Method 2
The reactant-wettable reactant collection surfaces located in the exhaust gas flow can be heated by the exhaust gas itself
Implementation Method 3
assisting the evaporation of the reactant impinging upon or wetting them
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An exhaust system for an internal combustion engine comprises an exhaust gas flow channel (14) through which exhaust gas flows in a main exhaust gas flow direction (A) and a reaction agent injection arrangement (18) for injecting reaction agent in a reaction agent injection area (16) of the exhaust gas flow channel (14) in a main reaction agent injection direction (R), wherein the main reaction agent injection direction (R) and the main exhaust gas flow direction (A) in the reaction agent injection area (16) are not parallel and not orthogonal to each other, but are arranged at a preferably acute angle.