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Type: Journal Article
Author(s): Xinyan Huang; Guillermo Rein
Publication Date: 2017

Smouldering fires in peatland are different from the flames in wildland fires. Smouldering peat fire is slow, low-temperature and more persistent, releasing large amounts of smoke into the atmosphere. In this work, we experimentally and computationally investigate the vertical downward spread of smouldering fire in a column of 30 cm-tall moss peat under variable moisture content (MC) and bulk density. The measured downward spread rate decreases with depth and wet bulk density, and is ~1 cm h−1 equivalent to a carbon emission flux of 200 tonnes day−1 ha−1. We observe that downward spread increases as MC increases substantially at least inside the range from 10 to 70%, which is not intuitive and goes against the trend observed for the horizontal spread in the same peat. We also conduct one-dimensional computational simulations to successfully reproduce the experimental observations. The analysis shows that the spread rate increases with MC and decreases with density because smouldering spread is controlled by the oxygen supply. The volume of the porous peat expands when absorbing water, which reduces the density of organic matter and decreases the heat release rate. This shows that the widely assumed conclusion that the spread rate of wildfire decreases with MC is not universal when applied to smouldering fires.

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Citation: Huang, Xinyan; Rein, Guillermo. 2017. Downward spread of smouldering peat fire: the role of moisture, density and oxygen supply. International Journal of Wildland Fire 26(11):907-918.

Cataloging Information

Alaska    California    Eastern    Great Basin    Hawaii    Northern Rockies    Northwest    Rocky Mountain    Southern    Southwest    National
  • carbon emissions
  • fire spread
  • peatland
  • rate of spread
  • smoldering fires
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Record Maintained By: FRAMES Staff (
FRAMES Record Number: 25198