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4D In-Situ Microscopy of Aerosol Filtration in a Wall Flow Filter

Authors
  • Jones, Matthew P.1
  • Storm, Malte
  • York, Andrew P. E.
  • Hyde, Timothy I.
  • Hatton, Gareth D.
  • Greenaway, Alex G.
  • Haigh, Sarah J.
  • Eastwood, David S.2
  • 1 & Innovation Campus, Didcot, Oxfordshire OX11 0FA, UK
  • 2 (G.D.H.)
Type
Published Article
Journal
Materials
Publisher
MDPI AG
Publication Date
Dec 12, 2020
Volume
13
Issue
24
Identifiers
DOI: 10.3390/ma13245676
PMID: 33322695
PMCID: PMC7763601
Source
PubMed Central
Keywords
Disciplines
  • Article
License
Green

Abstract

The transient nature of the internal pore structure of particulate wall flow filters, caused by the continuous deposition of particulate matter, makes studying their flow and filtration characteristics challenging. In this article we present a new methodology and first experimental demonstration of time resolved in-situ synchrotron micro X-ray computed tomography (micro-CT) to study aerosol filtration. We directly imaged in 4D (3D plus time) pore scale deposits of TiO 2 nanoparticles (nominal mean primary diameter of 25 nm) with a pixel resolution of 1.6 μ m. We obtained 3D tomograms at a rate of ∼1 per minute. The combined spatial and temporal resolution allows us to observe pore blocking and filling phenomena as they occur in the filter’s pore space. We quantified the reduction in filter porosity over time, from an initial porosity of 0.60 to a final porosity of 0.56 after 20 min. Furthermore, the penetration depth of particulate deposits and filtration rate was quantified. This novel image-based method offers valuable and statistically relevant insights into how the pore structure and function evolves during particulate filtration. Our data set will allow validation of simulations of automotive wall flow filters. Evolutions of this experimental design have potential for the study of a wide range of dry aerosol filters and could be directly applied to catalysed automotive wall flow filters.

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