Influence of soil conditions on the multidimensional spread of smouldering combustion in shallow layers
File(s)
Accepted version
Author(s)
Christensen, Eirik G
Fernandez-Anez, Nieves
Rein, Guillermo
Type
Journal Article
Abstract
Smouldering peatland fires are capable of burning vast amounts of organic soils, resulting in the release of greenhouse gases into the atmosphere, as well as a significant deterioration of air quality causing in major regional crises known as haze events. Fundamental understanding of smouldering fire spread is essential for the development of mitigating technologies. In this paper, we have systematically conducted 63 experiments studying the individual and combined influence of two key factors affecting multidimensional smouldering spread in organic soils: moisture content (MC) and inorganic content (IC). Both lateral and in-depth smouldering spread were investigated using a novel shallow reactor. This shallow depth allows a greater number of experiments to be performed in a short period of time compared to deeper samples. Lateral spread was found to decrease linearly with moisture content (R2 > 90%); while in-depth spread rate increased linearly up to 300% from moisture content of 0% to 140%. Increased inorganic content linearly decreased the lateral spread rate but had little influence on in-depth spread in drier samples. Interestingly, in wetter samples, in-depth spread was in fact sensitive to inorganic content. A novel approach combining lateral and in-depth spread rates as vector components, revealed that the global spread is independent of moisture content, with an average spread rate of 8.7 and 8.4 cm/h for 2.5 and 40% IC, with changes in direction according to moisture content; going in-depth for wet soils, and laterally for dry soils. Similarly, increasing the IC encouraged downward spread for wet samples. We also report observations of a bifurcation of lateral spread, where spread would locally extinguish where the in-depth spread was greater than the lateral spread. These findings provide previously unknown insight into the relationship between lateral and in-depth spread in smouldering fires, ultimately improving the fundamental understanding of such fires.
Date Issued
2020-04-01
Date Acceptance
2019-11-06
Citation
Combustion and Flame, 2020, 214, pp.361-370
ISSN
0010-2180
Publisher
Elsevier
Start Page
361
End Page
370
Journal / Book Title
Combustion and Flame
Volume
214
Copyright Statement
© 2020 Elsevier Ltd. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence http://creativecommons.org/licenses/by-nc-nd/4.0/
Sponsor
Commission of the European Communities
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000524457200032&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Grant Number
682587
Subjects
Science & Technology
Physical Sciences
Technology
Thermodynamics
Energy & Fuels
Engineering, Multidisciplinary
Engineering, Chemical
Engineering, Mechanical
Engineering
Fire
Wildfire
Heat transfer
Biomass
Smouldering
PARTICLE EMISSIONS
TRANSIENT GAS
PEAT FIRES
MOISTURE
IGNITION
CONSUMPTION
Publication Status
Published
Date Publish Online
2020-01-24