Combustion of Metallic Powders: A Phenomenological Model for the Initiation of Combustion

Hilmar Rode, Vladimir Hlavacek, Hendrik J Viljoen, Jorge E. Gatica

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

A mathematical model which describes the process when a spherical metallic particle is exposed to an oxidizing atmosphere, has been formulated. We refer to the oxidation process in a generic sense, and the model can be used for the formation of oxides, nitrides and sulphides in general. The oxidation process is modeled for oxides which form n-type semiconductors with the defects in the form of interstitial cations and electrons (e.g., A12O3) in terms of mass and energy transport phenomena. It accounts for the release of metal cations and electrons at the metal-oxide interface, the transport of these species through the oxide layer due to concentration and electric field gradients, and the formation of the metal oxide at the outer interface. As a result a hollow oxide sphere develops as the metal is converted to oxide. If the energy released by the oxidation reaction exceeds the heat losses, self-heating will occur. Such a rise in temperature accelerates the release of cations and electrons from the metal into the oxide as well as the transport of cations. This can eventually lead to the total combustion of the particle. The model is solved numerically by the Galerkin Finite Element Method. The effects of several process variables are investigated for the aluminum-oxygen case study: initial passivating oxide layer thickness, average particle size, storage temperature and oxidant partial pressure, and heat losses. For certain limiting conditions, a simplified model is developed, and an approximate analytical treatment is presented.

Original languageEnglish (US)
Pages (from-to)153-175
Number of pages23
JournalCombustion Science and Technology
Volume88
Issue number3-4
DOIs
StatePublished - Feb 1 1993

Fingerprint

Powders
Oxides
oxides
Metals
Cations
cations
Positive ions
oxidation
metal oxides
Heat losses
Oxidation
metals
Electrons
heat
n-type semiconductors
electrons
nitrides
partial pressure
sulfides
hollow

Keywords

  • Combustion
  • gas-solid reactions
  • pyrophoricity
  • self-heating

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Physics and Astronomy(all)

Cite this

Combustion of Metallic Powders : A Phenomenological Model for the Initiation of Combustion. / Rode, Hilmar; Hlavacek, Vladimir; Viljoen, Hendrik J; Gatica, Jorge E.

In: Combustion Science and Technology, Vol. 88, No. 3-4, 01.02.1993, p. 153-175.

Research output: Contribution to journalArticle

Rode, Hilmar ; Hlavacek, Vladimir ; Viljoen, Hendrik J ; Gatica, Jorge E. / Combustion of Metallic Powders : A Phenomenological Model for the Initiation of Combustion. In: Combustion Science and Technology. 1993 ; Vol. 88, No. 3-4. pp. 153-175.
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