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

Abstract

A scanning electron microscope (SEM) was used to dynamically visualize the particulate matter (PM) trapping process on diesel particulate filter (DPF) walls at a micro scale as 'time-lapse' images corresponding to the increase in pressure drop simultaneously measured through the DPF. This visualization and pressure drop measurement led to the conclusion that the PM trapping in surface pores was driven by PM bridging and stacking at constricted areas in porous channels. This caused a drastic increase in the pressure drop during PM accumulation at the beginning of the PM trapping process. The relationship between the porous structure of the DPF and the depth of the surface pore was investigated in terms of the porosity distribution and PM penetration depth near the wall surface with respect to depth. The pressure drop calculated with an assumed surface pore depth showed a good correspondence to the measured pressure drop.

Soot Trapping by High-permeability Porous Membrane Filter Made of Aggregates of Alumina Nanoparticles

“…Figure 10 shows the increase in the pressure drop for each superficial velocity. In the case of 34.5 mm/s, similarly to the case of the soot-trapping process in the previous work (1) , we observe three phases of the increase in the pressure drop: caused by the bridging-structure formation, the deposition of nanoparticles in surface pores, and the growth of the cake layer. With decreasing velocity, the increase in the pressure drop due to the deposition in surface pores became smaller.…”

“…Recently, the mechanism of the increase in the pressure drop with respect to soot loading was revealed (1) (Figure 1). At the beginning of soot deposition, the soot is trapped on the surface of grains, which are the elements of the DPF.…”

“…The sample was comprised of a 5 × 5 matrix where individual cells were alternately plugged. To visualize the crosssection of the vertical wall of the DPF, the horizontal outer wall was removed from the sample (1) . The top surfaces of the vertical walls were well-polished uniformly using abrasive papers with grit sizes ranging from P400 to P4000.…”

Scanning Electron Microscopic Time-lapse Visualization of Ash Movement During Regeneration of Diesel Particulate Filters

“…Then, it was put into DPF holder, made of stainless steel, and ceramic paste was used to seal around DPF sample and holder. In order to visualize the cross-sectional vertical wall of the DPF, the horizontal top wall was removed (8,9) . The top surfaces of the vertical walls and the holder were polished simultaneously and uniformly utilizing abrasive papers with grit sizes ranging from As a result, the PM included ash with a weight ratio of 11 wt.%.…”

Development of Membrane filter Made of Alumina and Silver-Palladium Particles for High-Filtration Efficiency, Low-Pressure Drop and Low-Soot Oxidation Temperature

“…The recent study [2] has revealed the pressure drop increasing phenomenon due to the soot accumulation on the particulate filter.…”