Exhaust Aftertreatment Conical Inlet Vortex Mixing
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Solution Overview
Problem
Existing exhaust-gas aftertreatment systems for internal combustion engines with turbochargers face challenges in achieving stoichiometric exhaust-gas mixtures, leading to incomplete mixing and non-compliance with stringent emissions requirements, especially during lean operation.
Innovation Solution
An exhaust-gas aftertreatment device with a conically shaped inlet region and a scavenging valve system, featuring controllable guide blades that rotate to adjust the cross-sectional flow area, generating vortex flows for improved mixing of exhaust gases with air, allowing for flexible control of the exhaust-gas/air mixture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If air scavenging operations are performed with large overlap in valve control timing to achieve high specific end torque, then the compressor can be operated with high efficiency at high throughflow rate, but the exhaust-gas/air mixture ratio becomes lean (lambda ≈ 1.3) which does not meet emissions requirements
Solution Approach 1:
A mixing device is introduced as an intermediary component between the engine and exhaust-gas aftertreatment device. This device actively mixes exhaust gas with scavenging air to achieve a stoichiometric mixture ratio (lambda ≈ 1), enabling the engine to operate in lean mode for high efficiency while meeting emissions requirements through controlled mixing downstream
Solution Approach 2:
The exhaust-gas/air mixture ratio is dynamically adjusted by controlling the amount of exhaust gas mixed with scavenging air. By varying the mixture ratio from lean (for power) to stoichiometric (for emissions), the system can optimize both performance and environmental compliance across different operating conditions
2Object-affected harmful factors
If a mixing device is positioned between the engine and exhaust-gas aftertreatment device to achieve stoichiometric mixture, then emissions requirements may be met, but mixing between scavenging gas and exhaust gas remains incomplete leading to poorly mixed gas mixtures
Solution Approach 1:
The mixing device employs curved surfaces and vortex-generating geometries to enhance mixing. The conical shape with increasing diameter in flow direction creates rotational flow patterns that promote thorough mixing of exhaust gas and scavenging air, ensuring homogeneous composition before entering the aftertreatment device
Solution Approach 2:
The mixing device utilizes vortex flows and turbulent mixing mechanisms to intensify the mixing process. The geometric design induces rotational motion and eddies that accelerate the mixing of gases, achieving complete and homogeneous mixing within a compact space
3Reliability
If the exhaust gas inlet region has a conical shape with increasing diameter to optimize flow and mixing, then catalytic converter performance and cold-start operation are improved, but the device complexity increases
Solution Approach 1:
The exhaust gas inlet region employs an asymmetric conical geometry with diameter increasing in the flow direction. This asymmetric shape optimizes flow distribution, reduces turbulence losses, and enhances mixing efficiency, leading to improved catalytic converter performance and cold-start operation while maintaining manufacturing feasibility
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 enables efficient air scavenging operations that meet emissions requirements across various operating conditions, optimizing catalytic converter performance, reducing heat losses, and enhancing cold-start operation by controlling the exhaust-gas/air mixture ratio.
Implementation Method 1
generating vortex flows for improved mixing of exhaust gases with air
Data Source
AI summary
Methods and systems are provided for an exhaust gas system. In one example, a system comprises a conical passage fluidly coupling a turbine outlet to an aftertreatment device. The conical passage may further comprise a scavenge valve to adjust exhaust gas flow therethrough.