SCR Vortex Generators and Virtual Mixers for Reductant Mixing
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Solution Overview
Problem
Conventional exhaust aftertreatment systems for internal combustion engines face challenges in mixing reductant with exhaust gas effectively, leading to reductant deposits on system components due to recirculation zones and increased back pressure from traditional mixers, which are complex and costly to manufacture.
Innovation Solution
The implementation of vortex generators and virtual mixers that generate vortices and electromagnetic fields to enhance mixing, preventing recirculation and promoting uniform distribution of reductant, thereby reducing deposits and back pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mixers with vanes or flow control features are used to promote mixing of reductant with exhaust gas, then mixing effectiveness is improved, but back pressure increases, space occupation increases, weight increases, and manufacturing complexity increases
Solution Approach 1:
The patent replaces conventional mechanical mixers with vanes or flow control features with a virtual mixer that uses electromagnetic fields to achieve mixing. The virtual mixer generates an electromagnetic field across the reductant spray to promote droplet breakage and decomposition without mechanical moving parts, thereby eliminating the complexity, weight, and space issues associated with traditional mechanical mixing components while maintaining or improving mixing effectiveness
Solution Approach 2:
The patent changes the physical state and parameters of the reductant by applying electromagnetic fields to accelerate droplet evaporation and decomposition. By controlling electromagnetic field parameters (frequency, intensity), the system achieves effective mixing and decomposition without requiring complex mechanical structures, thus resolving the contradiction between mixing effectiveness and device complexity
2Stability of the object's composition
If recirculation zones are present in the exhaust gas flow, then boundary layer detachment occurs, but reductant deposits form on surfaces due to lower temperature and shear velocity in recirculation zones
Solution Approach 1:
The vortex generators create controlled vortices and turbulence in the exhaust gas flow, which prevents boundary layer detachment and eliminates recirculation zones. This mechanical disturbance of the flow pattern ensures that exhaust gas maintains higher velocity and temperature along surfaces, preventing reductant deposits from forming while maintaining flow stability
Solution Approach 2:
The vortex generators act as intermediary elements that modify the exhaust gas flow characteristics. By introducing controlled vortices, they serve as a mediator between the exhaust gas flow and the housing surfaces, preventing direct contact between reductant droplets and surfaces where deposits would form, thus eliminating the harmful effect without disrupting overall flow stability
3Reliability
If reductant is not substantially mixed with exhaust gas, then decomposition is incomplete, but reductant deposits form on aftertreatment system components
Solution Approach 1:
The virtual mixer performs preliminary action by applying electromagnetic fields to the reductant spray before it enters the main decomposition zone. This pre-treatment accelerates droplet breakage and initial decomposition, ensuring more complete mixing and decomposition occurs upstream, which prevents downstream deposit formation while improving overall decomposition completeness
Solution Approach 2:
The patent uses electromagnetic fields instead of mechanical mixing devices to achieve thorough mixing and decomposition. The electromagnetic field acts on the reductant droplets to promote evaporation and decomposition without requiring mechanical contact, thereby achieving complete decomposition while preventing deposits from forming on mechanical components
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 proposed solution improves NOx conversion efficiency and reduces emissions by ensuring complete decomposition and uniform distribution of reductant across the SCR system, minimizing reductant deposits and system complexity while maintaining low back pressure.
Implementation Method 1
a vortex generator disposed in the housing, the vortex generator comprising at least one deflector disposed on a surface within the housing, the at least one deflector configured to generate vortices in a portion of the exhaust gas flow flowing over the at least one deflector
Implementation Method 2
a virtual mixer configured to generate an electric or electromagnetic field across the reductant spray as it exits the injection nozzle, which promotes droplet breakage and a faster decomposition rate in the exhaust stream
Data Source
AI summary
An aftertreatment system for treating constituents of an exhaust gas produced by an engine, comprising: a housing; a selective catalytic reduction (SCR) system disposed within the housing; a reductant injector disposed on a sidewall of the housing upstream of the SCR system and configured to insert a reductant into the exhaust gas; and a vortex generator disposed in the housing, the vortex generator comprising at least one deflector disposed on a surface within the housing, the at least one deflector configured to generate vortices in a portion of the exhaust gas flow flowing over the at least one deflector such that the portion of the exhaust gas remains attached to the surface at a downstream location of the surface.