Honeycomb Filter Cell Geometry for NOx Conversion
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Solution Overview
Problem
Conventional honeycomb filters face challenges in achieving high NOx conversion performance due to insufficient contact between exhaust gas and the catalyst, leading to poor NOx conversion efficiency and increased pressure loss, especially after the accumulation of PMs.
Innovation Solution
The honeycomb filter design features exhaust gas emission cells fully surrounded by exhaust gas introduction cells with varying cross-sectional areas and volumes, ensuring efficient gas flow and catalyst contact, reducing pressure loss throughout the filter's operational life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If exhaust gas introduction cells have the same cross-sectional area as exhaust gas emission cells, then the structure is simple and easy to manufacture, but the NOx conversion performance is poor due to insufficient contact between exhaust gas and catalyst
Solution Approach 1:
The patent applies local quality by creating two distinct types of exhaust gas introduction cells: first introduction cells with smaller cross-sectional areas and second introduction cells with larger cross-sectional areas. This non-uniform design optimizes local flow characteristics to enhance exhaust gas-catalyst contact efficiency, thereby improving NOx conversion performance while maintaining manufacturing feasibility through standardized cell patterns.
2Reliability
If the honeycomb filter structure is optimized to improve NOx conversion performance, then catalyst contact efficiency increases, but the device complexity increases
Solution Approach 1:
The patent segments the exhaust gas introduction cells into two functional types: first introduction cells with smaller cross-sections for specific flow control and second introduction cells with larger cross-sections for enhanced catalyst contact. This segmentation strategy improves NOx conversion performance while maintaining a repeating pattern that limits overall structural complexity.
3Reliability
If PMs accumulate in the honeycomb filter, then filtration function is improved, but pressure loss increases significantly
Solution Approach 1:
The patent employs parameter changes by varying the cross-sectional areas of different introduction cells. The smaller first introduction cells and larger second introduction cells create diverse flow paths that optimize exhaust gas distribution. This parameter variation maintains effective catalyst contact and reduces pressure loss even after PM accumulation, as the varied cell geometry prevents flow stagnation and promotes continuous gas-catalyst interaction.
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 design enhances NOx conversion performance and minimizes pressure loss both initially and after PM accumulation, improving fuel economy and reducing the adverse effects of increased pressure on engine performance.
Implementation Method 1
the cell walls supporting an SCR catalyst
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3(a)~3(b)
AI summary
The present invention provides a honeycomb filter that can have high NOx conversion performance without supporting an excessive amount of catalyst or having an increased volume. The honeycomb filter of the present invention includes porous cell walls, exhaust gas emission cells each having a plugged end, and exhaust gas emission cells each having a plugged end, wherein the cell walls support an SCR catalyst. The exhaust gas emission cells have a larger average cross sectional area than the exhaust gas introduction cells in a direction perpendicular to the longitudinal direction of the cells, and the exhaust gas introduction cells have a larger total volume than the exhaust gas emission cells.