Ceramic Honeycomb Filter Pore Distribution for Pressure Loss and Strength
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Solution Overview
Problem
Ceramic honeycomb filters for large diesel engines face challenges in achieving both high particulate matter capturing efficiency and low pressure loss while maintaining sufficient strength to withstand mechanical vibration and shock, as existing technologies often compromise on either strength or pressure loss characteristics.
Innovation Solution
The ceramic honeycomb structure is optimized with a balanced pore distribution, including a porosity of 58-66%, average pore size of 15-32 µm, and specific pore size distribution, combined with a production method using extrusion-molding and sintering of cordierite-forming and pore-forming materials, to achieve reduced pressure loss and increased strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the porosity and pore size of cell walls are increased to reduce pressure loss, then the pressure loss decreases, but the strength of the ceramic honeycomb filter decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the porosity (58-66%) and average pore size (15-32 µm) of the cell walls, along with specific pore size distribution parameters (d10, d50, d90). This optimization balances the competing requirements of low pressure loss and high strength, resolving the contradiction between these two parameters.
Solution Approach 2:
The patent uses a composite material system consisting of cordierite-forming material (60-70 wt%), pore-forming material (10-20 wt%), and binder (5-15 wt%). This composite approach allows the ceramic structure to achieve both the desired porous characteristics for low pressure loss and sufficient mechanical strength through the synergistic combination of different materials.
2Productivity
If the porosity of cell walls is increased to improve air permeability, then the air permeability increases, but the isostatic strength decreases
Solution Approach 1:
The patent resolves this contradiction by optimizing the porosity parameter to a specific range (58-66%) and controlling the pore size distribution (average pore size 15-32 µm). This parameter optimization ensures sufficient air permeability for high productivity while maintaining adequate isostatic strength for structural integrity.
Solution Approach 2:
The patent applies local quality by creating a specific pore size distribution within the cell walls, where pores of different sizes (controlled by d10, d50, d90 parameters) are distributed to provide both air permeability pathways and structural support, allowing different regions of the porous structure to serve different functions.
3Loss of energy
If the average pore size is increased to reduce pressure loss, then the pressure loss decreases, but the strength deteriorates
Solution Approach 1:
The patent resolves this contradiction by precisely controlling the average pore size parameter (15-32 µm) along with the pore size distribution parameters (d10, d50, d90). This optimized parameter set achieves low pressure loss while maintaining strength, unlike conventional approaches that use uniformly large pores which compromise strength.
Solution Approach 2:
The composite material system (cordierite-forming material, pore-forming material, and binder) enables the creation of a pore structure with controlled average size and distribution, where the material composition supports both the desired pore characteristics for low pressure loss and the structural requirements for 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
This approach results in ceramic honeycomb filters with improved air permeability, isostatic strength, and pressure loss characteristics, making them suitable for large diesel engines without compromising on either strength or pressure loss.
Implementation Method 1
heating a molded material comprising a cordierite-forming material and a pore-forming material; sintering the molded material at a highest temperature of 1380-1435°C
Data Source
Figure 1(a)~1(b)
Figure 2~3
Figure 4~5
AI summary
A ceramic honeycomb structure having a large number of flow paths defined by porous cell walls having porosity of 45-68% and an average pore size of 15-35 µm, the volume of pores having diameters of more than 50 µm being more than 10% and 25% or less of the total pore volume, the volume of pores having diameters of 100 µm or more being 1-8% of the total pore volume, the volume of pores having diameters of less than 10 µm being 3-10% of the total pore volume, and the pores having a pore size distribution deviation σ [= log(D20) - log(D80)] of 0.45 or less, wherein D20 represents a pore size (µm) at a pore volume corresponding to 20% of the total pore volume, and D80 represents a pore size (µm) at a pore volume corresponding to 80% of the total pore volume, in a curve showing the relation between a pore size and a cumulative pore volume obtained by accumulating a pore volume from the maximum pore size to a particular pore size, and D80 < D20.