Honeycomb Structure with Mixed Cell Diameters for Soot Clogging Resistance
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Solution Overview
Problem
Conventional honeycomb structures used as catalyst carriers for oxidation catalysts face challenges in achieving high cell density while preventing cell clogging due to soot, particularly when increasing cell density leads to smaller opening diameters that are prone to clogging.
Innovation Solution
A honeycomb structure with a combination of large and small opening cells, where the ratio of their diameters is between 1.11 and 1.28, and a cell density between 93 and 104 cells per square centimeter, along with a specific thickness, porosity, and average pore diameter of the partition wall, effectively reduces soot clogging while maintaining high cell density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the cell density of the honeycomb structure is increased, then the oxidation performance is improved through increased contact area between exhaust gas and catalyst, but the opening diameter per cell becomes smaller and cell clogging by soot becomes more容易发生
Solution Approach 1:
The patent applies local quality by creating two distinct cell types with different opening diameters within the same honeycomb structure. Large opening cells (with opening diameter L1) provide resistance to soot clogging, while small opening cells (with opening diameter L2) increase the overall cell density and catalyst contact area. The ratio L1/L2 is controlled between 1.05 and 1.20 to optimize the balance between these two functions.
2Productivity
If the amount of catalyst is increased to improve oxidation performance, then the purification efficiency is enhanced, but the cost increases due to the high price of noble metal catalysts
Solution Approach 1:
The patent applies parameter changes by modifying the physical structure of the honeycomb carrier rather than changing the chemical composition or amount of catalyst. By adjusting the cell density, opening diameters, and their ratio, the patent increases the effective contact area between exhaust gas and catalyst, thereby improving oxidation performance without increasing the quantity of expensive noble metal catalyst material.
3Speed
If the opening diameter of cells is reduced to increase cell density, then more cells can be packed into the same area, but soot particles can easily clog the smaller openings
Solution Approach 1:
The patent applies segmentation by dividing the cell population into two distinct groups: large opening cells and small opening cells. This segmentation allows each cell type to perform a specialized function - large cells handle soot transport and resistance to clogging, while small cells provide high density and increased catalyst contact area. The combination of these segmented cell types resolves the contradiction between cell density and soot clogging resistance.
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 proposed honeycomb structure effectively suppresses cell clogging and maintains high cell density, enhancing oxidation performance and isostatic strength, while also improving purification efficiency and reducing pressure loss.
Implementation Method 1
a porous partition wall disposed so as to surround a plurality of cells, which serving as fluid through channels
Data Source
AI summary
A honeycomb structure includes a pillar-shaped honeycomb structure body having a porous partition wall disposed to surround a plurality of cells, which serving as fluid through channels extending from a first end face to a second end face, wherein the plurality of cells includes: large opening cells having a large opening area on the first end face and the second end face; and small opening cells having an opening area smaller than that of the large opening cells on the first end face and the second end face, a ratio of an opening diameter of the large opening cells to an opening diameter of the small opening cells is larger than 1.11 and smaller than 1.28, and the opening diameter of the small opening cells is larger than 0.78 mm, and a cell density of the honeycomb structure body is larger than 93 pcs/cm2 and smaller than 104 pcs/cm2.