Electron microscopic time-lapse visualization of surface pore filtration on particulate matter trapping process

Area of Science:

• Mechanical Engineering
• Materials Science
• Environmental Science

Background:

• Diesel engines produce particulate matter (PM), necessitating exhaust aftertreatment systems like diesel particulate filters (DPF).
• Understanding PM trapping mechanisms is crucial for optimizing DPF efficiency and longevity.
• Previous studies often lacked micro-scale dynamic visualization of the PM trapping process.

Purpose of the Study:

• To dynamically visualize the micro-scale particulate matter (PM) trapping process on diesel particulate filter (DPF) walls.
• To correlate PM trapping mechanisms with pressure drop changes within the DPF.
• To investigate the relationship between DPF porous structure and PM penetration depth.

Main Methods:

• Utilized scanning electron microscopy (SEM) for time-lapse visualization of PM trapping.
• Simultaneously measured pressure drop across the DPF during PM accumulation.
• Analyzed porosity distribution and PM penetration depth in relation to filter depth.

Main Results:

• PM trapping in surface pores is driven by bridging and stacking at constricted areas.
• This mechanism causes a significant increase in pressure drop at the beginning of PM accumulation.
• Calculated pressure drop based on assumed surface pore depth correlated well with measured values.

Conclusions:

• PM trapping in DPFs is a dynamic process influenced by pore structure and PM accumulation patterns.
• The initial drastic pressure drop increase is attributed to PM bridging and stacking in surface pores.
• The study provides insights into DPF filtration mechanisms and validates models for predicting pressure drop.