Variable Geometry Exhaust Conduit for Reductant Deposit Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional exhaust aftertreatment systems for IC engines face challenges in maintaining sufficient shear stress to prevent reductant deposits at low engine flow rates, leading to increased maintenance costs and reduced catalytic efficiency.
Innovation Solution
The system adjusts the cross-sectional area of the exhaust conduit based on the initial flow rate to increase the flow velocity of the exhaust gas, using a cross-section adjusting mechanism and flow rate sensors to ensure sufficient shear stress is maintained, thereby preventing reductant deposits and optimizing catalytic conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the cross-sectional area of the exhaust conduit is kept large to reduce backpressure, then exhaust flow resistance is reduced, but flow velocity decreases leading to insufficient shear stress and reductant deposits
Solution Approach 1:
The exhaust conduit employs a variable cross-sectional area design where the area changes along the flow direction, creating different flow conditions in different sections. The larger cross-sectional area at the inlet reduces backpressure, while the reduced cross-sectional area downstream increases flow velocity and shear stress to prevent reductant deposits.
2Object-generated harmful factors
If the cross-sectional area is reduced to increase flow velocity and shear stress, then reductant deposits are prevented, but backpressure increases
Solution Approach 1:
Different sections of the exhaust conduit have different cross-sectional areas tailored to local requirements. The inlet section has a larger area to minimize backpressure, while downstream sections have reduced areas to generate sufficient shear stress and prevent reductant deposits in specific zones where deposits are most problematic.
3Device complexity
If a fixed cross-sectional area is used, then the system is simple, but it cannot maintain sufficient shear stress across varying engine operating conditions
Solution Approach 1:
The exhaust conduit design changes the geometric parameter (cross-sectional area) along the flow direction to optimize performance. By progressively reducing the cross-sectional area from inlet to outlet, the system maintains sufficient shear stress across varying engine operating conditions while preserving catalytic efficiency without requiring complex active control mechanisms.
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 approach effectively maintains sufficient shear stress on the exhaust conduit walls to remove reductant deposits, reducing maintenance costs and ensuring efficient catalytic conversion even at low engine flow rates.
Implementation Method 1
maintain a sufficient shear stress in the exhaust conduit to prevent the formation of reductant pools or reductant deposits
Implementation Method 2
The reducing of the cross-sectional area causes the exhaust gas to have an adjusted flow velocity greater than the initial flow velocity
Data Source
AI summary
A method for reducing reductant deposits in an exhaust conduit fluidly coupled to an engine comprises operating the engine to produce an exhaust gas. The exhaust gas is communicated into the exhaust conduit which has an initial cross-sectional area. An initial flow rate corresponding to an initial flow velocity of the exhaust gas entering the exhaust conduit is determined. The initial flow rate and, thereby the initial flow velocity of the exhaust gas, increases or decreases based on an operating condition of the engine. The initial flow rate of the exhaust gas is compared with a predetermined threshold. If the initial flow rate of the exhaust gas is lower than the predetermined threshold, a cross-sectional area of the exhaust conduit is reduced. The reducing of the cross-sectional area causes the exhaust gas to have an adjusted flow velocity greater than the initial flow velocity.