Contoured Honeycomb Body for Uniform Exhaust Gas Flow
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Solution Overview
Problem
Existing catalytic converters with cylindrical honeycomb bodies having flat inlet and outlet surfaces suffer from non-uniform gas flow distribution, leading to reduced efficiency and shorter lifespan due to uneven exhaust gas flow patterns, resulting in decreased conversion efficiency and increased pressure drop.
Innovation Solution
A honeycomb body with a contoured outlet end face is designed to provide uniform exhaust gas residence time across the radial area, reducing the ratio of maximum to minimum residence time by at least 20%, achieved through a manufacturing method that determines local channel velocities and adjusts channel lengths to optimize flow distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a cylindrical honeycomb body with flat inlet and outlet surfaces is used, then the manufacturing process is simple, but the gas flow distribution becomes non-uniform with most exhaust gases directed to the central portion
Solution Approach 1:
The inlet end face is divided into multiple radial zones (central region and peripheral region) with different contour shapes. The central region has a first contour shape while the peripheral region has a second contour shape, creating locally optimized flow patterns to achieve uniform overall flow distribution.
Solution Approach 2:
The inlet end face features an asymmetric contour configuration where the central region and peripheral region have different radial distances from the longitudinal axis. This asymmetric design intentionally creates varied flow paths to counteract the natural tendency of exhaust gases to concentrate in the central portion.
2Reliability
If non-uniform flow distribution occurs with high velocity exhaust gases flowing through the center, then conversion efficiency decreases and catalyst deactivation occurs, but increasing the expansion angle or using conical/arcuate shapes only partially improves flow uniformity
Solution Approach 1:
Different radial zones of the inlet end face are given different contour characteristics. The central region uses a first contour shape optimized for its high flow velocity, while the peripheral region uses a second contour shape optimized for its lower flow velocity, achieving local optimization of flow distribution.
Solution Approach 2:
The inlet end face is segmented into a central region and a peripheral region based on radial distance from the longitudinal axis. Each region is independently contoured to address the specific flow characteristics of that zone, with the segmentation allowing for differentiated flow management.
3Reliability
If the expansion angle between inlet and casing is altered to improve flow distribution, then some flow uniformity is achieved, but non-uniform flow distribution persists and conversion efficiency remains reduced
Solution Approach 1:
The contour design applies different radial distance characteristics to different regions. The central region has a different radial distance from the longitudinal axis compared to the peripheral region, creating locally optimized flow patterns that achieve uniform overall flow distribution and improve conversion efficiency.
Data Source
AI summary
Engine exhaust gas treatment article comprising a contoured honeycomb body (300) including a contoured outlet end face (316) are disclosed. Also disclosed are methods of manufacturing an engine exhaust gas treatment article.