Honeycomb Structure Circumferential Wall Gap Path Thermal Stress
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Solution Overview
Problem
Honeycomb structures with high porosity and thin partition walls suffer from low strength and are prone to cracking during high-temperature calcination due to thermal stress, which can lead to catalyst leakage.
Innovation Solution
A honeycomb structure with a circumferential wall thickness of 0.5 to 4.0 mm and a gap path inside the wall, where the gap path has a width of 0.4 to 4.0 mm and a height of 50 to 99% of the wall thickness, providing a total length of 1000% or more of the cell extending direction, to mitigate thermal stress and prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the circumferential coating layer is applied to the honeycomb structure, then the structural strength is improved, but thermal stress during calcination causes cracks to form
Solution Approach 1:
The circumferential coating layer is segmented by forming gap paths that divide it into multiple sections. These gap paths allow the coating to expand and contract independently during thermal cycles, reducing stress concentration and preventing crack formation while maintaining overall structural strength.
Solution Approach 2:
The gap paths create local variations in the circumferential coating layer, providing different functional zones: areas with gap paths for stress relief and areas without gap paths for structural support. This local differentiation allows the coating to simultaneously achieve both strength and crack resistance.
2Quantity of substance
If the partition wall is made thin to increase porosity, then the catalytic efficiency is improved, but the mechanical strength decreases
Solution Approach 1:
The gap paths are formed in the circumferential coating layer before the calcination process. This preliminary structural preparation allows the coating to accommodate thermal expansion stresses during subsequent high-temperature treatment, preventing cracks that would otherwise compromise the thin partition walls and maintain both porosity and strength.
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 honeycomb structure effectively maintains isostatic strength and prevents catalyst leakage by releasing thermal stress through the gap path, enhancing thermal shock resistance and maintaining structural integrity during temperature changes.
Implementation Method 1
a crack is generated in the calcination of a catalyst. Particularly, a honeycomb structure with a high porosity and a honeycomb structure with a thin partition wall have a low strength. Therefore, when the circumferential coating layer becomes high temperature (for example, in the calcination of a catalyst), a partition wall constituting the honeycomb structure cannot withstand stress generated by thermal expansion of the circumferential coating layer
Data Source
AI summary
A honeycomb structure includes a honeycomb structure body that includes a porous partition wall which defines a plurality of cells serving as through channels of fluid and extending from an inflow end face as one end face to an outflow end face as the other end face, and a circumferential wall arranged on a circumferential surface of the honeycomb structure body. The circumferential wall has a thickness of 0.5 to 4.0 mm, a gap path is formed along a surface of the circumferential wall inside the circumferential wall, the gap path has a width of 0.4 to 4.0 mm, and has a height of 50 to 99% of the thickness of the circumferential wall, and a total length of the gap path is 1000% or more of a length in the cell extending direction of the honeycomb structure body.