Honeycomb Filter Cell Geometry and Catalyst Distribution
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Solution Overview
Problem
Honeycomb filters struggle to efficiently purify CO and HC in exhaust gas due to insufficient catalyst support and excessive pressure loss, particularly after catalyst coating and regeneration treatment, leading to incomplete conversion and increased pressure loss.
Innovation Solution
A honeycomb filter design with exhaust gas emission cells having a larger average cross-sectional area than introduction cells, where an oxidation catalyst is supported inside the cell walls, ensuring efficient gas flow and contact with the catalyst before and after PM accumulation, reducing pressure loss by optimizing cell structure and catalyst distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a catalyst is supported on the cell walls of a honeycomb filter to purify CO and HC in exhaust gas, then the purification efficiency is improved, but the pressure loss increases excessively
Solution Approach 1:
The invention applies local quality by supporting the oxidation catalyst only on the inner peripheral surfaces of the cell walls in the exhaust gas introduction cells, rather than uniformly across all surfaces. This localized catalyst placement optimizes contact with exhaust gas flowing through the introduction cells while minimizing obstruction to gas flow, thereby achieving effective CO and HC purification without excessive pressure loss increase
Solution Approach 2:
The invention segments the honeycomb filter into distinct functional zones: exhaust gas introduction cells with catalyst-supported cell walls, and exhaust gas emission cells with open ends. This segmentation allows exhaust gas to flow through introduction cells where purification occurs, then exit through emission cells, separating the purification function from the flow path to reduce overall pressure loss
2Ease of operation
If the cell structure is optimized to reduce initial pressure loss, then the ease of operation is improved, but the purification performance may be compromised
Solution Approach 1:
The invention maintains large cell dimensions for both introduction and emission cells to minimize flow resistance and pressure loss, while simultaneously supporting the catalyst only on the cell wall peripheries rather than filling the entire cell interior. This local quality approach ensures that the bulk cell volume remains open for easy gas flow, while the catalytic surfaces are concentrated where they are most effective for purification
Solution Approach 2:
The invention transitions from a two-dimensional surface coating approach to a three-dimensional structural integration by forming the catalyst as part of the cell wall structure itself. The cell walls serve dual functions as both structural elements defining large open cells for low pressure loss and as catalyst carriers, with the catalyst integrated into the wall matrix rather than applied as a separate surface layer
3Reliability
If an oxidation catalyst is supported inside the cell walls to convert CO generated during PM combustion, then the purification efficiency is improved, but the device complexity increases
Solution Approach 1:
The invention applies universality by making the cell walls serve multiple functions: they provide structural support for the honeycomb filter, define the boundaries of introduction and emission cells, and simultaneously serve as the support medium for the oxidation catalyst. This multi-functionality eliminates the need for separate catalyst carriers or complex support structures, reducing device complexity while maintaining effective CO purification
Solution Approach 2:
The invention merges the structural function of the cell walls with the catalytic function by integrating the oxidation catalyst directly into the cell wall material. Rather than using separate components for structure and catalysis, the cell walls themselves become the catalyst support, combining what would otherwise be distinct elements into a single integrated structure
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 design enhances CO and HC purification efficiency while minimizing pressure loss throughout the filter's operational life, maintaining low initial and transitional pressure loss even after PM accumulation.
Implementation Method 1
an oxidation catalyst is supported inside the cell walls
Implementation Method 2
oxidation catalyst...efficiently converting CO
Implementation Method 3
porous cell walls defining rims of the plurality of cells
Implementation Method 4
honeycomb filter...capture PMs in exhaust gas
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3(a)~3(b)
AI summary
The present invention provides a honeycomb filter capable of purifying CO generated by combustion of PMs as well as HC and CO which are leaked out after insufficient conversion with an oxidation catalyst disposed in front of the honeycomb filter, without a complex catalyst coating process and without applying an excessive amount of catalyst. The honeycomb filter of the present invention includes porous cell walls, and exhaust gas introduction cells and exhaust gas emission cells each having an plugged end, wherein an oxidation catalyst is supported inside the cell walls in an amount of 5 to 60 g/L; the exhaust gas emission cells have a larger average cross sectional area in a direction perpendicular to the longitudinal direction than the exhaust gas introduction cells in a direction perpendicular to the longitudinal direction; and the total volume of the exhaust gas introduction cells is larger than the total volume of the exhaust gas emission cells.