Ceramic Honeycomb Filter Pore Distribution for PM Capture
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Solution Overview
Problem
Ceramic honeycomb filters for diesel engines struggle to effectively capture nano-sized particulate matter at the early stage of use while maintaining low pressure loss, failing to meet stricter exhaust gas regulations due to insufficient number-based capturing ratio and pressure loss characteristics.
Innovation Solution
A ceramic honeycomb structure with a specific pore diameter distribution and porosity range, produced using a method involving extrusion-molding with ceramic and hollow resin particles, which includes a porosity of 50-60%, and a pore diameter distribution curve measured by mercury porosimetry, ensuring effective capture of nano-sized PM without significant pressure loss deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the porosity and pore diameter distribution are optimized to improve the capturing ratio of nano-sized PM, then the number-based capturing ratio of PM is improved, but the pressure loss increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the pore diameter distribution parameters (d10, d50, d85, d90, d98) and porosity (50-60%) of the ceramic honeycomb structure. This optimization creates a specific pore size distribution that enhances nano-sized PM capture while maintaining acceptable pressure loss characteristics, directly resolving the contradiction between capturing efficiency and energy loss.
Solution Approach 2:
The patent implements local quality by creating different pore diameter zones within the cell walls. The pore diameter distribution is non-uniform, with specific ranges for different percentile diameters (d10=15-35μm, d50=10-20μm, d85=5-9μm, d90=3-8μm, d98≤2.5μm). This localized variation in pore size allows the structure to capture particles of different sizes efficiently while maintaining overall permeability.
2Reliability
If the pore diameter distribution is controlled to enhance nano-particle capture, then the number-based capturing ratio improves, but the pressure loss characteristics deteriorate
Solution Approach 1:
The patent uses parameter changes by defining specific ranges for pore diameter percentiles (d10, d50, d85, d90, d98) and porosity. The constrained parameters include d10/d50 ratio (0.75-1.1), d50/d90 ratio (1.3-1.8), and σ value (≤0.39), which collectively optimize nano-particle capture while controlling pressure loss through mathematical relationships between pore size parameters.
Solution Approach 2:
The patent applies dynamics by balancing the pore structure characteristics to adapt to different operating conditions. The specific pore diameter distribution allows the filter to maintain effective capture of nano-sized particles across varying exhaust flow rates and particle concentrations, dynamically adjusting performance based on operating conditions while managing pressure loss.
3Loss of energy
If the porosity is increased to reduce pressure loss, then the pressure loss characteristics improve, but the capturing ratio of PM decreases
Solution Approach 1:
The patent applies parameter changes by optimizing porosity within a specific range (50-60%) rather than maximizing it. This controlled porosity level, combined with the specific pore diameter distribution parameters, achieves a balance where sufficient permeability is maintained for low pressure loss while enough pore walls remain to capture PM effectively.
Solution Approach 2:
The patent implements local quality by creating regions with different pore characteristics within the cell walls. The non-uniform pore diameter distribution (with d10, d50, d85, d90, d98 representing different zones) allows certain areas to provide capture functionality while other areas maintain permeability, resolving the contradiction between filtration efficiency and pressure loss.
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 solution enables improved number-based capturing ratio of PM even at the early stage of use and maintains low pressure loss characteristics when PM is accumulated, effectively meeting stricter exhaust gas regulations.
Implementation Method 1
While passing through the cell walls 2, particularly through communicating pores on and in the cell walls 2, PM is captured, cleaning the exhaust gas.
Implementation Method 2
the method involves extrusion-molding with ceramic and hollow resin particles
Data Source
Figure 1~2
Figure 3~4
AI summary
A ceramic honeycomb structure having pluralities of flow paths partitioned by porous cell walls; (a) the cell walls having porosity of 50-60%; and (b) in a pore diameter distribution in the cell walls measured by mercury porosimetry, (i) a pore diameter d5 at a cumulative pore volume corresponding to 5% of the total pore volume being 22 µm or more and less than 55 µm, a pore diameter d10 at 10% being 15-35 µm, a pore diameter d50 at 50% being 10-20 µm, a pore diameter at 85% being 5-9 µm, a pore diameter d90 at 90% being 3-8 µm, a pore diameter d98 at 98% being 2.5 µm or less, (d10 - d90)/d50 being 1.3-1.8, (d50 - d90)/d50 being 0.45-0.75, and (d10 - d50)/d50 being 0.75-1.1; and (ii) the difference between a logarithm of the pore diameter at a cumulative pore volume corresponding to 20% of the total pore volume and a logarithm of the pore diameter at 80% being 0.39 or less, and its production method.