Honeycomb Filter Segment Joining for Pressure Loss and Heat Stress
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Solution Overview
Problem
Conventional honeycomb filters with a segment structure experience increased pressure loss and heat stress due to the reduction in through channel area and unrestricted deformation between segments, which limits their effectiveness in collecting particulate matter from exhaust gases.
Innovation Solution
A honeycomb filter design with a segment structure where the outflow end surface area is larger than the inflow end surface area, featuring a decreasing joining layer thickness and absence of joining layers in the region 5 mm or more from the outflow end surface, allowing for increased gas flow and thermal expansion to reduce pressure loss and heat stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If honeycomb segments are joined by joining material to reduce heat stress, then heat stress resistance is improved, but the through channel area decreases causing increased pressure loss
Solution Approach 1:
The joining layer thickness varies along the axial direction of the honeycomb filter. The thickness is greater in the upstream section where heat stress is lower, and gradually decreases toward the downstream section where heat stress is highest. This local variation in joining layer thickness allows the filter to maintain structural integrity while minimizing the reduction in through channel area in the critical downstream region, thus balancing heat stress resistance with pressure loss reduction.
2Strength
If joining layers are applied throughout the entire length of honeycomb segments, then structural strength is improved, but heat stress increases due to restricted thermal expansion
Solution Approach 1:
The joining layers are segmented along the axial direction rather than being continuous. The downstream section, which experiences the highest heat stress and thermal expansion, is left without joining layers or with significantly reduced joining layer thickness. This segmentation allows the honeycomb segments to expand thermally in the high-temperature zone while maintaining structural strength in the upstream and middle sections where joining layers are present.
3Stress or pressure
If the through channel area is reduced by joining material, then heat stress is decreased due to reduced thermal mass, but pressure loss increases
Solution Approach 1:
The joining layer thickness is optimized locally along the axial direction. In the downstream section where heat stress is most critical, the joining layer thickness is minimized or eliminated to maintain large through channel area for adequate gas flow. In the upstream and middle sections, joining layers of appropriate thickness are applied to reduce heat stress without significantly impacting the overall gas flow performance.
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 suppresses pressure loss and decreases heat stress, enhancing the filter's ability to collect particulate matter while preventing damage from heat stress during regeneration.
Implementation Method 1
a thickness of each of the joining layers which join the side surfaces of the honeycomb segments to each other decreases in at least a part of the joining layer in a direction from the inflow end surface side toward an outflow end surface side
Implementation Method 2
the exhaust gas permeates the porous partition walls, and the particulate matter in the exhaust gas is collected by the porous partition walls
Implementation Method 3
the burning and removing of the particulate matter will be referred to as the regeneration of the filter sometimes
Data Source
AI summary
A honeycomb filter 100 includes honeycomb segments 4, plugging portions 5, and joining layers 7, area of outflow end surface 12 of honeycomb segment is larger than area of inflow end surface 11, and shape of cross section of honeycomb segment vertical to axial direction X has a similarity in axial direction X. Moreover, thickness of joining layer decreases in at least a part of joining layer in direction from inflow end surface side toward outflow end surface side, and length L2 of joining layer in axial direction X is smaller than 95% of length L1 of honeycomb segment in axial direction X. Furthermore, a region of honeycomb segments 4, 5 mm or more from outflow end surface 12 in axial direction X, is not provided with joining layers 7 which join side surfaces of honeycomb segments 4 to each other.