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Study of ignition and extinction of small-scale fires in experiments with an emulating gas burner

Lundström, Frida Vermina LU ; Sunderland, Peter B.; Quintiere, James G.; van Hees, Patrick LU and de Ris, John L. (2017) In Fire Safety Journal 87. p.18-24
Abstract

The objective of this study is to explore mechanisms for ignition and extinction for condensed-phase fuels via the use of a gas-fueled burner. Flames were generated with a porous 25 mm circular burner using mixtures of methane and propane with nitrogen. The procedure was to specify a set of mass fluxes of nitrogen-fuel mixture that corresponded to the flash- fire- and extinction points and for the minimum mass flux where steady burning was achieved. The results show an increase in the critical mass flux with a decreased heat of combustion. The data fall into two regimes depending on the mixture flow rate; one buoyancy-driven (Fr<1) and one induced by momentum jet forces. The buoyancy-driven regime is geometrically consistent with the... (More)

The objective of this study is to explore mechanisms for ignition and extinction for condensed-phase fuels via the use of a gas-fueled burner. Flames were generated with a porous 25 mm circular burner using mixtures of methane and propane with nitrogen. The procedure was to specify a set of mass fluxes of nitrogen-fuel mixture that corresponded to the flash- fire- and extinction points and for the minimum mass flux where steady burning was achieved. The results show an increase in the critical mass flux with a decreased heat of combustion. The data fall into two regimes depending on the mixture flow rate; one buoyancy-driven (Fr<1) and one induced by momentum jet forces. The buoyancy-driven regime is geometrically consistent with the definitions of flash and fire points under natural convection conditions. The results for the momentum regime align reasonably with existing stagnant layer theory. Extinction theory is also suggested to give approximate results for the fire point. This argument is based on similar flame geometries for fire point and extinction and theoretical reasoning. An anchor point is proposed as the end point of ignition. Produced anchor point data result in a flammability diagram, below which quasi-steady burning occurs.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Combustion, Heat flux gage, Laminar diffusion flame
in
Fire Safety Journal
volume
87
pages
7 pages
publisher
Elsevier
external identifiers
  • scopus:84998679643
  • wos:000394069900003
ISSN
0379-7112
DOI
10.1016/j.firesaf.2016.11.003
language
English
LU publication?
yes
id
b4a681f8-e472-4cf8-a912-5a6bf5113bab
date added to LUP
2017-02-27 09:00:47
date last changed
2017-10-02 10:11:18
@article{b4a681f8-e472-4cf8-a912-5a6bf5113bab,
  abstract     = {<p>The objective of this study is to explore mechanisms for ignition and extinction for condensed-phase fuels via the use of a gas-fueled burner. Flames were generated with a porous 25 mm circular burner using mixtures of methane and propane with nitrogen. The procedure was to specify a set of mass fluxes of nitrogen-fuel mixture that corresponded to the flash- fire- and extinction points and for the minimum mass flux where steady burning was achieved. The results show an increase in the critical mass flux with a decreased heat of combustion. The data fall into two regimes depending on the mixture flow rate; one buoyancy-driven (Fr&lt;1) and one induced by momentum jet forces. The buoyancy-driven regime is geometrically consistent with the definitions of flash and fire points under natural convection conditions. The results for the momentum regime align reasonably with existing stagnant layer theory. Extinction theory is also suggested to give approximate results for the fire point. This argument is based on similar flame geometries for fire point and extinction and theoretical reasoning. An anchor point is proposed as the end point of ignition. Produced anchor point data result in a flammability diagram, below which quasi-steady burning occurs.</p>},
  author       = {Lundström, Frida Vermina and Sunderland, Peter B. and Quintiere, James G. and van Hees, Patrick and de Ris, John L.},
  issn         = {0379-7112},
  keyword      = {Combustion,Heat flux gage,Laminar diffusion flame},
  language     = {eng},
  month        = {01},
  pages        = {18--24},
  publisher    = {Elsevier},
  series       = {Fire Safety Journal},
  title        = {Study of ignition and extinction of small-scale fires in experiments with an emulating gas burner},
  url          = {http://dx.doi.org/10.1016/j.firesaf.2016.11.003},
  volume       = {87},
  year         = {2017},
}