Honeycomb Filter Gradient Particle Size Pressure Loss
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Solution Overview
Problem
Honeycomb filters used in exhaust gas cleaning devices face issues with high pressure loss and reduced collection efficiency due to the accumulation of particulate matter (PM) in the cell walls, leading to a 'depth filtration' state where the effective porosity is reduced.
Innovation Solution
A honeycomb filter design featuring a ceramic substrate with a filter layer composed of spherical ceramic particles, where the average particle size increases gradually from the fluid inlet side to the fluid outlet side, optimizing pore size for efficient PM trapping and reducing pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a honeycomb filter is used to trap PM in exhaust gas, then collection efficiency is improved, but pressure loss increases due to depth filtration
Solution Approach 1:
The filter layer is applied selectively only to specific cells (alternate cells) rather than all cells uniformly. This creates local filtration zones that trap PM effectively while leaving other cells as low-resistance flow paths, thus reducing overall pressure loss while maintaining collection efficiency.
Solution Approach 2:
The honeycomb filter structure is segmented into alternate open cells and sealed cells with filter layers. This segmentation allows the exhaust gas to flow through multiple pathways, where some cells provide filtration and others provide low-resistance flow, resolving the contradiction between collection efficiency and pressure loss.
2Reliability
If particles are deposited to form a composite region, then collection efficiency is improved, but pressure loss increases due to reduced effective porosity
Solution Approach 1:
The filter layer is formed using porous ceramic particles with controlled pore structures. These porous materials provide large surface area for PM trapping while maintaining sufficient void space for gas flow, thus achieving high collection efficiency without excessive pressure loss.
Solution Approach 2:
A composite structure is created by combining the honeycomb substrate with a filter layer of ceramic particles. This composite material integrates the structural support of the honeycomb with the filtration capability of the particle layer, achieving both collection efficiency and acceptable pressure loss characteristics.
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 achieves low pressure loss and high collection efficiency by ensuring small pore sizes at the inlet for trapping small PM and larger pore sizes at the outlet for reduced pressure drop, while maintaining heat resistance and mechanical integrity.
Implementation Method 1
a filter layer which, among the surfaces of the cell walls, is formed on the surface of the cell walls of those cells in which the end section at the fluid inlet side is open and the end section at the fluid outlet side is sealed
Data Source
Figure 1~2
Figure 3~4
Figure 5(a)~5(b)
AI summary
An object of the present invention is to provide a honeycomb filter having low pressure loss and high collection efficiency. The honeycomb filter of the present invention comprises a ceramic honeycomb substrate in which a multitude of cells through which a fluid flows are disposed in parallel in a longitudinal direction and are separated by cell walls, each cell being sealed at an end section at either the fluid inlet side or the fluid outlet side, and a filter layer which, among the surfaces of the cell walls, is formed on the surface of the cell walls of those cells in which the end section at the fluid inlet side is open and the end section at the fluid outlet side is sealed by a sealing material, wherein the filter layer comprises spherical ceramic particles, and the average particle size of the spherical ceramic particles increases gradually from the fluid inlet side toward the fluid outlet side.