Honeycomb Filter Defect Detection via Fog Flow
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Solution Overview
Problem
Honeycomb filters used in exhaust gas streams face efficiency and integrity issues due to defects like holes or cracks in the porous walls or plugs, which allow unfiltered fluid to pass through, necessitating effective testing methods to detect and potentially repair or discard such filters.
Innovation Solution
A method involving maintaining a honeycomb filter at a temperature range of 10°C to 30°C, flowing fog with moisture droplets of 1-25 microns at 80% relative humidity, and monitoring the exit for defects by wetting the end portions to enhance sensitivity and pressure differential, using a test apparatus to detect defects in the porous walls and plugs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional testing methods are used to detect defects in honeycomb filters, then the testing process is simple, but the detectability of defects is insufficient
Solution Approach 1:
The patent applies parameter changes by controlling temperature (10°C to 30°C), humidity (at least 80% relative humidity), and pressure differential across the honeycomb filter during testing. These parameter optimizations enhance the detectability of defects in porous walls and plugs by creating conditions that maximize fog droplet penetration through defects while maintaining stability in the testing process
Solution Approach 2:
The patent uses fog droplets as a proxy or copy to detect defects. Instead of directly observing structural defects, the method employs moisture droplets that penetrate through defects in the porous walls and plugs, allowing indirect detection of defects that would otherwise be difficult to identify
2Reliability
If the honeycomb filter is tested without controlled environmental conditions, then the testing procedure is simpler, but the consistency and reliability of defect detection are reduced
Solution Approach 1:
The patent maintains specific environmental parameters including temperature between 10°C to 30°C and relative humidity of at least 80%. These parameter controls ensure reliable and consistent defect detection by preventing fog droplet evaporation and maintaining stable testing conditions throughout the examination process
Solution Approach 2:
The patent applies prior cushioning by pre-controlling the environmental conditions before initiating the defect detection process. By establishing stable temperature and humidity conditions beforehand, the method ensures that the fog droplets maintain their properties throughout the testing duration, preventing premature evaporation or condensation that could affect detection reliability
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
This method effectively increases the detectability of defects within the honeycomb filter, improving filtration efficiency and integrity by identifying and potentially addressing issues in the filter's structure.
Implementation Method 1
When particulates, such as soot found in exhaust gas, flow through the interconnecting porous walls 106 of the honeycomb filter 100, a portion of the particulates in the fluid flow stream is retained by the interconnecting porous walls 106.
Implementation Method 2
flowing a fog with moisture droplets into the honeycomb network of channels at the first end portion of the honeycomb filter, the fog including a relative humidity of at least 80%
Data Source
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AI summary
Methods of testing a honeycomb filter include the step of maintaining an average temperature of the honeycomb filter and/or fog within a range of from about 10°C to about 30°C and flowing a fog with moisture droplets into the honeycomb network of channels at the first end portion of the honeycomb filter, the fog including a relative humidity of at least 80%. In further examples, the moisture droplets include a mean droplet size of from about 1 micron to about 25 microns.