Hollow Particle Filter Layer for Thermal Stress Management
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Solution Overview
Problem
Honeycomb filters used for trapping particulate matter (PM) in exhaust gas face issues with thermal stress during regeneration, leading to filter layer detachment and sudden pressure loss due to depth filtration.
Innovation Solution
A ceramic honeycomb filter with a filter layer composed of hollow particles on the surface of cell walls, where the end section at the fluid inlet is open and the end section at the fluid outlet is sealed, reduces heat capacity and thermal stress, preventing filter layer detachment and depth filtration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a filter layer is formed on the cell walls to trap PM, then PM trapping capability is improved, but thermal stress during regeneration causes filter layer detachment
Solution Approach 1:
The patent changes the physical structure of particles from solid to hollow, which fundamentally alters the heat capacity parameter. This parameter change allows the filter layer to respond differently to thermal stress during regeneration, preventing detachment while maintaining PM trapping capability.
Solution Approach 2:
The patent creates a composite structure by forming a filter layer composed of hollow particles on the cell walls. This composite material combines the filtering function with reduced thermal mass, solving both the PM trapping requirement and the thermal stress problem simultaneously.
2Stability of the object's composition
If the filter layer has high heat capacity to withstand thermal stress, then filter layer stability is improved, but temperature difference during regeneration increases causing detachment
Solution Approach 1:
The patent changes the heat capacity parameter by using hollow particles instead of solid particles. This reduces the thermal mass of the filter layer, allowing it to heat up and cool down more quickly, thereby reducing the temperature difference with cell walls during regeneration cycles and preventing detachment.
3Reliability
If PM is trapped in fine pores of cell walls (depth filtration), then PM trapping efficiency is improved, but effective porosity is reduced causing sudden pressure loss
Solution Approach 1:
The patent uses hollow particles with controlled porosity to create a filter layer that traps PM on its surface rather than allowing depth filtration into cell wall pores. The porous structure of hollow particles provides large surface area for PM capture while maintaining permeability, thus preventing sudden 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 filter layer's reduced heat capacity and optimized particle size and solidity of hollow particles prevent filter layer detachment and sudden pressure loss, ensuring effective PM trapping and maintaining filter integrity during regeneration.
Implementation Method 1
the heat produced by the PM incineration accumulates in the filter layer, causing the temperature of the filter layer to increase. However, the temperature of the cell walls tends to remain low, so that thermal stress develops between the filter layer and the cell walls
Implementation Method 2
The PM accumulated on the surface of the filter layer is incinerated in the regeneration process
Data Source
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AI summary
An object of the present invention is to provide a honeycomb filter which is resistant to detachment of the filter layer during regeneration processing, while suppressing any sudden increase in pressure loss caused by depth filtration. 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, wherein the filter layer comprises hollow particles.