Particulate Filter Pore Size Distribution for Pressure Drop
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Solution Overview
Problem
Wall-flow particulate filters experience a rapid increase in pressure drop during the initial deep-bed filtration stage, leading to increased back pressure and decreased engine performance, due to their geometric and microstructural properties, which also affect filtration efficiency and initial pressure drop.
Innovation Solution
A particulate filter with porous walls having a total porosity greater than 45%, a median pore size ranging from 13 to 16 micrometers, and a pore size distribution where pores less than 10 micrometers contribute less than 6% porosity, designed to minimize initial back pressure increase and maintain high filtration efficiency during deep-bed filtration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional porous walls are used in wall-flow particulate filters, then filtration efficiency is achieved, but pressure drop increases rapidly during deep-bed filtration stage
Solution Approach 1:
The patent applies parameter changes by optimizing the pore size distribution of the porous walls. Specifically, it sets the median pore size between 13-16 micrometers and ensures that pores less than 10 micrometers contribute less than 6% to total porosity, while total porosity exceeds 45%. These parameter adjustments resolve the contradiction by maintaining filtration efficiency through appropriate pore sizing while reducing pressure drop by limiting the proportion of small pores that create high flow resistance.
Solution Approach 2:
The patent utilizes porous materials with specifically engineered properties. The porous walls are designed with controlled pore size distribution where the majority of porosity comes from larger pores (13-16 micrometer median), which provide adequate filtration while offering lower flow resistance compared to conventional filters with higher proportions of small pores. This resolves the contradiction between filtration efficiency and pressure drop by using porous materials with optimized structural characteristics.
2Stress or pressure
If porous walls with higher porosity are used, then initial pressure drop is reduced, but filtration efficiency during deep-bed filtration decreases
Solution Approach 1:
The patent resolves this contradiction through precise parameter control of the pore size distribution. By setting total porosity greater than 45% while simultaneously ensuring that pores less than 10 micrometers contribute less than 6% to total porosity and the median pore size is 13-16 micrometers, the design achieves both low initial pressure drop (through high overall porosity and larger pores) and maintained filtration efficiency (through adequate pore size for particle capture).
Solution Approach 2:
The porous wall structure functions as a composite material system where the pore size distribution is engineered to combine the benefits of high porosity (low pressure drop) with sufficient small pore content (filtration efficiency). The composite pore structure integrates larger pores for low resistance flow with a controlled amount of smaller pores for particle capture, resolving the contradiction between initial pressure drop and filtration efficiency.
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 achieves a low pressure drop when clean and a gradual increase in back pressure during deep-bed filtration, enhancing engine fuel economy and filtration efficiency while maintaining high filtration performance.
Implementation Method 1
Particulate capture by the porous walls can occur in two different stages: at first, inside the porous wall (deep-bed filtration)
Implementation Method 2
later, on the porous wall in the flow channels (cake-bed filtration)
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A~4B
AI summary
A particulate filter [100] may comprise an inlet end [102], an outlet end [104], and a plurality of channels [108, 110] disposed and configured to flow fluid from the inlet end [102] to the outlet end [104], wherein the channels [108, 110] are defined by porous walls [106] configured to trap particulate matter. The porous walls [106] may have a total porosity greater than about 45 %, a median pore size that ranges from about 13 micrometers to about 20 micrometers, and a pore size distribution such that pores less than 10 micrometers contribute less than about 10 % porosity.