Honeycomb Filter With Gradually Thickening Layer
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Solution Overview
Problem
Honeycomb filters used in exhaust gas cleaning devices face challenges in achieving a balance between high collection efficiency and low pressure loss due to uneven PM deposition and filter layer thickness, leading to increased pressure loss and reduced collection efficiency.
Innovation Solution
A honeycomb filter design with a ceramic substrate and a filter layer that gradually increases in thickness from the fluid inlet side to the outlet side, combined with a thin layer region between the inlet and outlet sides, to reduce exhaust gas velocity and PM deposition at the outlet side, while maintaining low pressure loss and high collection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a uniform thickness filter layer is formed across the entire surface of cell walls, then the manufacturing process is simple, but the collection efficiency is reduced at the outlet side where PM deposition is high
Solution Approach 1:
The filter layer thickness is made non-uniform, with greater thickness at the outlet side where PM deposition is high and thinner thickness at the inlet side. This local variation in thickness optimizes PM collection efficiency at different positions along the cell walls, addressing the uneven deposition pattern caused by gas flow velocity variations.
2Reliability
If the filter layer thickness is increased to accumulate more PM, then the collection efficiency is improved, but the pressure loss increases due to reduced gas flow
Solution Approach 1:
The filter layer thickness is optimized locally: thicker at the outlet side where PM deposition is high to maximize collection efficiency, and thinner at the inlet side where gas flow velocity is lower and PM deposition is less. This local optimization allows sufficient PM accumulation without causing excessive pressure loss that would result from a uniformly thick filter layer.
3Reliability
If a thick filter layer is provided at the outlet side to prevent PM leakage, then the collection efficiency is improved, but the pressure loss increases
Solution Approach 1:
The filter layer is designed with locally optimized thickness: thicker regions are provided only where needed (outlet side with high PM deposition) to prevent PM leakage and ensure collection efficiency, while thinner regions are maintained in areas with lower PM deposition (inlet side). This localized approach achieves effective PM trapping without the excessive pressure loss that would result from a uniformly thick filter layer across the entire cell wall surface.
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 effectively reduces pressure loss and enhances collection efficiency by optimizing PM accumulation and filtration area, suitable for high porosity filters, with excellent mechanical strength and heat resistance.
Implementation Method 1
the filter layer has a role of accumulating and trapping PM on the filter layer
Implementation Method 2
the particles that are deposited in order to form the composite region are supplied and deposited by a gas-solid two phase flow
Data Source
AI summary
An object of the present invention is to provide a honeycomb filter capable of achieving a combination of high collection efficiency and low pressure loss. The honeycomb filter 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 thickness of the filter layer increases gradually from the fluid inlet side toward the fluid outlet side.