Honeycomb Filter Efficiency Testing Without Soot Contamination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods fail to accurately evaluate the filtration efficiency of particulate filters in a clean state, as they often contaminate the filter with soot or ash during testing, necessitating a need for alternative methods to assess filtration efficiency without loading the filter with contaminants.
Innovation Solution
A method involving sealing the outer peripheral portion of the filter to prevent gas flow, forcing a soot-free gas flow through the filter, and using diffraction-based optical particle counters to count particles entering and exiting the filter, ensuring the filter remains in a clean state during testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional laboratory methods are used to measure filtration efficiency, then measurement accuracy is improved, but the filter becomes contaminated with soot or ash during testing
Solution Approach 1:
The patent introduces a soot-free particle source (such as diatomaceous earth or synthetic particles) as an intermediary substance to replace traditional soot-generating methods. This intermediary particle source allows measurement of filtration efficiency without contaminating the filter with combustion byproducts, thereby resolving the contradiction between accurate measurement and filter contamination.
Solution Approach 2:
The patent replaces the mechanical/chemical process of generating soot through combustion with an optical detection system using diffraction-based optical particle counters. This substitution eliminates the need for burning materials that produce soot, allowing accurate particle counting and filtration efficiency measurement without introducing harmful contaminants to the filter.
2Productivity
If high-speed testing is implemented to test a large number of honeycomb bodies, then productivity is improved, but measurement variability may increase
Solution Approach 1:
The patent implements continuous particle generation and detection systems that maintain steady-state flow conditions throughout the testing process. The soot-free particle source continuously supplies particles at controlled concentrations, and the optical counters continuously monitor particle passage through the filter, enabling high-speed testing while maintaining measurement consistency and low variability.
Solution Approach 2:
The patent uses synthetic particle sources that replicate the size distribution and optical properties of actual exhaust particles without the harmful contaminants. This copying approach allows rapid, repeated testing of multiple filters under identical controlled conditions, improving productivity while maintaining measurement reliability through standardized test particles.
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
Enables accurate and efficient measurement of filtration efficiency without contaminating the filter, allowing for high-speed testing of a large number of honeycomb bodies, with low variability and strong correlation to traditional laboratory methods.
Implementation Method 1
optically counting the number of particles entering and exiting the filter during a sampling event, such as with diffraction based optical particle counters positioned upstream and downstream of the filter
Data Source
AI summary
Apparatus and methods are disclosed which are capable of being used to determine filtration efficiency of a filter body even in a clean state. Methods of determining a filtration efficiency of a filter including forcing an inlet flow comprised of a gas (such as air) flow into the inlet end of the filter at a set flow rate, introducing particles such as smoke particles into the inlet flow, and optically counting the number of particles entering and exiting the filter during a sampling event, such as with diffraction based optical particle counters positioned upstream and downstream of the filter. Preferably the gas flow is a soot-free flow stream which does not load the honeycomb filter body with contaminants that need to be removed or burned out. The filter body can thus remain in an essentially clean state even after testing its filtration efficiency.