Design and optimisation of a multifunctional monolithic filter for fire escape masks

Jonathan Barnard, Stuart Scott, Steve Tennison, Martin W. Smith, Michael W. Harral, Andrew Burrows, Semali Perera, John Chew

Research output: Contribution to journalArticlepeer-review

Abstract

Commercial fire escape masks (FEMs) use packed bed filters to remove gaseous and vaporous toxic components in the event of building fires. Packed bed filters incur a high pressure drop and commercial masks have no method to remove environmental (fire) or process (reaction and adsorption) heats. Here we derive a computationally efficient numeric model based on a bi-linear driving force (LDF) model to investigate the purification of gas streams in a square channelled monolith filter containing an impregnated activated carbon (AC) section to adsorb and react toxic components, and a section consisting of shape stable phase change materials (SS-PCMs) to absorb heat. The modelled test gas mixture contained an adsorbing component, cyclohexane, and a reacting component, carbon monoxide, permitting the combined effects of heat generation, heat absorption, component reaction and component adsorption to be studied for a novel filter. The bi-LDF model was validated against a three-dimensional model and provided excellent accuracy at significantly reduced computational time ca. 99.7%. Additionally, the bi-LDF model was used to optimise the dimensions and configuration of the filter, specifically finding an optimal channel diameter, d ch, to wall thickness, t w, aspect ratio of d ch=1.3t w. The optimal configuration consisted of an initial 2.0 cm long impregnated AC section followed by a 2.5 cm SS-PCM section at the outlet, providing 18 min of thermal protection whilst preventing cyclohexane vapour breakthrough for 21 min. Pt/TiO 2 was confirmed to be a viable CO oxidation catalyst with a minimum weight fraction within the impregnated monolith of 2.5 wt%. The success of this work represents a step change in FEM design and more widely in air purification devices where heat absorption is important.

Original languageEnglish
Article number132775
JournalChemical Engineering Journal
Volume430
Issue numberPart 2
Early online date8 Oct 2021
DOIs
Publication statusPublished - 15 Feb 2022

Keywords

  • Bi-linear driving force
  • CO oxidation
  • Fire escape masks
  • Monoliths
  • Phase change materials

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry
  • Chemical Engineering(all)
  • Industrial and Manufacturing Engineering

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