Particulate Filter Pore Structure for Soot Monitoring
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Solution Overview
Problem
Conventional wall-flow particulate filters face challenges in accurately monitoring soot levels due to pressure drop uncertainties, leading to premature or inadequate regeneration, which affects engine performance and fuel efficiency, and may result in filter failure or excessive regeneration events.
Innovation Solution
The development of particulate filters with specific geometric and microstructural properties, such as low cell density, controlled pore size distribution, and porosity, to achieve a low clean pressure drop and a steep pressure drop response during cake-bed filtration, while maintaining a low response during deep-bed filtration, thereby optimizing regeneration timing and reducing filter failure risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wall-flow particulate filters are used to remove particulates from exhaust gas, then filtration efficiency is improved, but pressure drop increases rapidly during initial deep-bed filtration stage
Solution Approach 1:
The patent applies different filtration mechanisms to different stages of particulate capture: deep-bed filtration for initial soot removal and cake-bed filtration for subsequent particulate accumulation. This local differentiation of filtration modes allows the system to maintain low pressure drop during initial operation while achieving high filtration efficiency through the combined mechanisms.
Solution Approach 2:
The patent performs preliminary soot removal through deep-bed filtration during the initial stage before cake-bed filtration begins. This preliminary action clears the porous walls of fine soot particles, preventing them from accumulating and causing rapid pressure drop increases later, thereby preparing the filter for more efficient cake-bed filtration.
2Reliability
If regeneration is triggered at low soot levels to avoid high filter temperatures, then filter failure is prevented, but regeneration frequency increases causing oil dilution and fuel penalty
Solution Approach 1:
The patent uses pressure drop as a feedback parameter to monitor soot levels and trigger regeneration. By carefully managing the pressure drop response characteristics of the filter, the system can accurately detect when soot reaches critical levels and trigger regeneration at the optimal moment, avoiding both premature regeneration and filter failure.
Solution Approach 2:
The patent modifies the pressure drop response parameters of the filter through controlled design and operation. By adjusting factors such as porous wall properties and flow characteristics, the filter exhibits optimized pressure drop behavior that enables accurate soot level monitoring and timely regeneration triggering, balancing filter safety with reduced regeneration frequency.
3Loss of energy
If pressure drop response is minimized during cake-bed filtration stage, then fuel efficiency is improved, but soot level monitoring accuracy deteriorates
Solution Approach 1:
The patent creates a dynamic pressure drop response characteristic where the filter transitions from shallow pressure drop response during deep-bed filtration to steeper response during cake-bed filtration. This dynamic behavior allows the system to maintain low pressure drop (improving fuel efficiency) while developing sufficient pressure drop signal (improving soot monitoring accuracy) as soot accumulates.
Solution Approach 2:
The patent performs preliminary deep-bed filtration to remove fine soot particles before cake-bed filtration begins. This preliminary action establishes a baseline pressure drop condition that enables subsequent cake-bed filtration to produce more pronounced and accurate pressure drop signals for soot level monitoring, while maintaining overall low pressure drop operation.
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 configuration promotes fuel economy, decreases regeneration frequency, and increases filtration efficiency by accurately triggering regeneration at critical soot levels, minimizing the risk of filter failure and maintaining high engine performance.
Implementation Method 1
Wall-flow particulate filters, for example, are often used in engine systems to remove particulates from the exhaust gas. Particulate capture by the porous walls can occur in two different stages: at first, inside the porous wall (deep-bed filtration), and later, on the porous wall in the flow channels (cake-bed filtration).
Implementation Method 2
soot is commonly oxidized and removed in a controlled regeneration process before excessive levels have accumulated
Implementation Method 3
This process, however, also releases energy in the form of heat, which raises the temperature of the filter
Data Source
Figure 1~2
Figure 3A~3B
Figure 4
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 cell density less than about 200 cpsi, a wall thickness of less than about 14 mils, a median pore size that ranges from about 13 micrometers to about 20 micrometers, a total porosity greater than about 45%, and a pore size distribution such that pores less than 10 micrometers contribute less than about 10% porosity.