Computational study of critical moisture and depth of burn in peat fires
Xinyan Huang A and Guillermo Rein A B
+ Author Affiliations
- Author Affiliations
A Department of Mechanical Engineering, Imperial College London, London SW7 2AZ, United Kingdom.
B Corresponding author. Email: g.rein@imperial.ac.uk
International Journal of Wildland Fire 24(6) 798-808 https://doi.org/10.1071/WF14178
Submitted: 1 October 2014 Accepted: 11 March 2015 Published: 30 July 2015
Journal Compilation © IAWF 2015
Abstract
Smouldering combustion is the slow, low-temperature, flameless burning of porous fuels and the most important phenomenon of wildfires in peatlands. Smouldering fires propagate both horizontally and vertically through organic layers of the ground and can reach deep into the soil. In this work, we develop a one-dimensional computational model of reactive porous media in the open-source code Gpyro. We investigate the vertical in-depth spread of smouldering fires into peat columns 20 cm deep with heterogeneous profiles of moisture content (MC), inert content (IC) and density. The model solves the species, momentum and energy conservation equations with five-step heterogeneous chemistry, to predict the transient profiles of temperature, species concentration, reaction rates and depth of burn from ignition to spread and to extinction. Modelling results reveal that smouldering combustion can spread over peat layers with very high MC (>250%) if the layer is thin and located below a thick, drier layer. It is shown that the critical moisture for extinction can be much higher than the previously reported critical MC for ignition (e.g. extinction MC up to 256% for low-IC peat, with critical ignition MC of 117%). The predicted critical MC values and depths of burn are compared with experimental measurements for field samples in the literature, showing good agreement. This study provides the physical understanding of the role of moisture in the ignition and extinction of smouldering peat fires, and explains for the first time the phenomenon of smouldering in very wet peat layers.
Additional keywords: extinction, ignition, modelling, peatland, smouldering, soil moisture, surface fuel, wildfire.
References
Benscoter BW, Thompson DK, Waddington JM, Flannigan MD, Wotton BM, de Groot WJ, Turetsky MR (2011) Interactive effects of vegetation, soil moisture and bulk density on depth of burning of thick organic soils. International Journal of Wildland Fire 20, 418–429.| Interactive effects of vegetation, soil moisture and bulk density on depth of burning of thick organic soils.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXlsFGlsLo%3D&md5=bf007bb32e6daa078bd254093327a707CAS |
Bergner K, Albano C (1993) Thermal analysis of peat. Analytical Chemistry 65, 204–208.
| Thermal analysis of peat.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK3sXkt1Skuw%3D%3D&md5=3f090aba0934fc30d9f549c50c0c1113CAS |
Cancellieri D, Leroy-Cancellieri V, Leoni E, Simeoni AYa, Kuzin A, Filkov AI, Rein G (2012) Kinetic investigation on the smouldering combustion of boreal peat. Fuel 93, 479–485.
| Kinetic investigation on the smouldering combustion of boreal peat.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC38XhtVGku7o%3D&md5=9c07dd4cd4fb434e39e6512b0981f433CAS |
Chen H, Zhao W, Liu N (2011) Thermal analysis and decomposition kinetics of Chinese forest peat under nitrogen and air atmospheres. Energy & Fuels 25, 797–803.
| Thermal analysis and decomposition kinetics of Chinese forest peat under nitrogen and air atmospheres.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXmtVensw%3D%3D&md5=63fa1e23395c45f79a770040af6af957CAS |
Davies GM, Gray A, Rein G, Legg CJ (2013) Peat consumption and carbon loss due to smouldering wildfire in a temperate peatland. Forest Ecology & Management 308, 169–177.
| Peat consumption and carbon loss due to smouldering wildfire in a temperate peatland.Crossref | GoogleScholarGoogle Scholar |
de Jonge H, Mittelmeijer-Hazeleger MC (1996) Adsorption of CO2 and N2 on soil organic matter: nature of porosity, surface area, and diffusion mechanisms. Environmental Science & Technology 30, 408–413.
| Adsorption of CO2 and N2 on soil organic matter: nature of porosity, surface area, and diffusion mechanisms.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK28XhtFWitg%3D%3D&md5=95f65b47b0cbf1b7fc20b7e3be745a1fCAS |
Frandsen WH (1987) The influence of moisture and mineral soil on the combustion limits of smoldering forest duff. Canadian Journal of Forest Research 17, 1540–1544.
| The influence of moisture and mineral soil on the combustion limits of smoldering forest duff.Crossref | GoogleScholarGoogle Scholar |
Frandsen WH (1997) Ignition probability of organic soils. Canadian Journal of Forest Research 27, 1471–1477.
| Ignition probability of organic soils.Crossref | GoogleScholarGoogle Scholar |
Garlough EC, Keyes CR (2011) Influences of moisture content, mineral content and bulk density on smouldering combustion of ponderosa pine duff mounds. International Journal of Wildland Fire 20, 589–596.
| Influences of moisture content, mineral content and bulk density on smouldering combustion of ponderosa pine duff mounds.Crossref | GoogleScholarGoogle Scholar |
Gorham E (1994) The future of research in Canadian peatlands: a brief survey with particular reference to global change. Wetlands 14, 206–215.
| The future of research in Canadian peatlands: a brief survey with particular reference to global change.Crossref | GoogleScholarGoogle Scholar |
Hadden RM, Rein G, Belcher CM (2013) Study of the competing chemical reactions in the initiation and spread of smouldering combustion in peat. Proceedings of the Combustion Institute 34, 2547–2553.
| Study of the competing chemical reactions in the initiation and spread of smouldering combustion in peat.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2cXhvV2ntbY%3D&md5=a9526bd00b43e630d30206a7f7c59628CAS |
Hartford R (1989) Smoldering combustion limits in peat as influenced by moisture, mineral content, and organic bulk density. In ‘Proceedings of the 10th Conference on Fire and Forest Meteorology’, 17–21 April, Ottawa, ON (Eds DC MacIver, H Auld, R Whitewood) pp. 282–286. (Atmospheric Environment Service: Downsview, ON)
Huang X, Rein G (2014) Smouldering combustion of peat in wildfires: Inverse modelling of the drying and the thermal and oxidative decomposition kinetics. Combustion & Flame 161, 1633–1644.
| Smouldering combustion of peat in wildfires: Inverse modelling of the drying and the thermal and oxidative decomposition kinetics.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2cXht1Cjs7Y%3D&md5=6bd168f67e53436d9c9258def31e1bdaCAS |
Huang X, Rein G, Chen H (2015) Computational smoldering combustion: predicting the roles of moisture and inert contents in peat wildfires. Proceedings of the Combustion Institute
| Computational smoldering combustion: predicting the roles of moisture and inert contents in peat wildfires.Crossref | GoogleScholarGoogle Scholar | , (In press)
Huggett C (1980) Estimation of rate of heat release by means of oxygen consumption measurements. Fire & Materials 4, 61–65.
| Estimation of rate of heat release by means of oxygen consumption measurements.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL3MXhslyktw%3D%3D&md5=2d04e7c4af93dbd85c093329829b0b24CAS |
Kim YH, Tong H, Daniels M, Boykin E, Krantz QT, McGee J, Hays M, Kovalcik K, Dye AJ, Gilmour MI (2014) Cardiopulmonary toxicity of peat wildfire particulate matter and the predictive utility of precision cut lung slices. Particle & Fibre Toxicology 11, 29–45.
| Cardiopulmonary toxicity of peat wildfire particulate matter and the predictive utility of precision cut lung slices.Crossref | GoogleScholarGoogle Scholar |
Lautenberger C, Fernandez-Pello C (2009) Generalized pyrolysis model for combustible solids. Fire Safety Journal 44, 819–839.
| Generalized pyrolysis model for combustible solids.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXotlOltL4%3D&md5=5feeb730d1659fd9516bd13a95778439CAS |
Leroy-Cancellieri V, Cancellieri D, Leoni E, Simeoni A, Filkov A (2014) Energetic potential and kinetic behavior of peats. Journal of Thermal Analysis & Calorimetry 117, 1497–1508.
| Energetic potential and kinetic behavior of peats.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2cXhtFeqs7%2FJ&md5=71fcee14e682c58523cf1722eb6e5adeCAS |
Moreno L, Jimenez ME, Aguilera H, Jimenez P, Losa A (2011) The 2009 smouldering peat fire in Las Tablas de Daimiel national park (Spain). Fire Technology 47, 519–538.
| The 2009 smouldering peat fire in Las Tablas de Daimiel national park (Spain).Crossref | GoogleScholarGoogle Scholar |
Ohlemiller T (1985) Modeling of smoldering combustion propagation. Progress in Energy & Combustion Science 11, 277–310.
| Modeling of smoldering combustion propagation.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL28XhsFWrtbY%3D&md5=9d69256b669e8ac6387e29d4ac3eb248CAS |
Page SE, Siegert F, Rieley JO, Boehm HDV, Jaya A, Limin S (2002) The amount of carbon released from peat and forest fires in Indonesia during 1997. Nature 420, 61–65.
| The amount of carbon released from peat and forest fires in Indonesia during 1997.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD38XosVCmu78%3D&md5=de5be6bef53f1d6ed9bf0771239b5938CAS | 12422213PubMed |
Poulter B, Christensen J, Norman L, Halpin PN (2006) Carbon emissions from a temperate peat fire and its relevance to interannual variability of trace atmospheric greenhouse gases. Journal of Geophysical Research, D, Atmospheres 111, D06301
| Carbon emissions from a temperate peat fire and its relevance to interannual variability of trace atmospheric greenhouse gases.Crossref | GoogleScholarGoogle Scholar |
Punmia B, Jain A (2005) ‘Soil Mechanics and Foundations.’ (Laxmi Publications: New Delhi, India)
Rappold AG, Stone SL, Cascio WE, Neas LM, Kilaru VJ, Carraway MS, Szykman JJ, Ising A, Cleve WE, Meredith JT, Vaughan-Batten H, Deyneka L, Devlin RB (2011) Peat bog wildfire smoke exposure in rural North Carolina is associated with cardiopulmonary emergency department visits assessed through syndromic surveillance. Environmental Health Perspectives 119, 1415–1420.
| Peat bog wildfire smoke exposure in rural North Carolina is associated with cardiopulmonary emergency department visits assessed through syndromic surveillance.Crossref | GoogleScholarGoogle Scholar | 21705297PubMed |
Rein G (2013) Smouldering fires and natural fuels. In ‘Fire Phenomena and the Earth System.’ (Ed. C Belcher) pp. 15–33. (Wiley & Sons: Oxford, UK)
Rein G, Cleaver N, Ashton C, Pironi P, Torero JL (2008) The severity of smouldering peat fires and damage to the forest soil. Catena 74, 304–309.
| The severity of smouldering peat fires and damage to the forest soil.Crossref | GoogleScholarGoogle Scholar |
Rein G, Cohen S, Simeoni A (2009) Carbon emissions from smouldering peat in shallow and strong fronts. Proceedings of the Combustion Institute 32, 2489–2496.
| Carbon emissions from smouldering peat in shallow and strong fronts.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXjvFyqsLw%3D&md5=5535a22b5c707b2090ca2d1ef508909bCAS |
Ryan KC, Frandsen WH (1991) Basal injury from smoldering fires in mature Pinus ponderosa laws. International Journal of Wildland Fire 1, 107–118.
| Basal injury from smoldering fires in mature Pinus ponderosa laws.Crossref | GoogleScholarGoogle Scholar |
Stephens SL, Finney MA (2002) Prescribed fire mortality of Sierra Nevada mixed conifer tree species: effects of crown damage and forest floor combustion. Forest Ecology & Management 162, 261–271.
| Prescribed fire mortality of Sierra Nevada mixed conifer tree species: effects of crown damage and forest floor combustion.Crossref | GoogleScholarGoogle Scholar |
Turetsky M, Benscoter B, Page S, Rein G, van der Werf GR, Watts A (2015) Global vulnerability of peatlands to fire and carbon loss. Nature Geoscience 8, 11–14.
| Global vulnerability of peatlands to fire and carbon loss.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2cXitFKltbbE&md5=c5d2c71f592345e74da9b275eb4185deCAS |
Wade D, Ewel J, Hofstetter R (1980) Fire in south Florida ecosystems. USDA Forest Service, South-eastern Forest Experiment Station, General Technical Report SE-17. (Asheville, NC)
Wagner CEV (1972) Duff consumption by fire in eastern pine stands. Canadian Journal of Forest Research 2, 34–39.
| Duff consumption by fire in eastern pine stands.Crossref | GoogleScholarGoogle Scholar |
Watts AC (2013) Organic soil combustion in cypress swamps: moisture effects and landscape implications for carbon release. Forest Ecology & Management 294, 178–187.
| Organic soil combustion in cypress swamps: moisture effects and landscape implications for carbon release.Crossref | GoogleScholarGoogle Scholar |
Yu F, Wei G, Zhang X, Chen K (2006) Two effective thermal conductivity models for porous media with hollow spherical agglomerates. International Journal of Thermophysics 27, 293–303.
| Two effective thermal conductivity models for porous media with hollow spherical agglomerates.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD28XmtVSms7Y%3D&md5=2de59259feb2df6f0a4409c12d8dfb04CAS |
Zaccone C, Rein G, D’Orazio V, Hadden RM, Belcher CM, Miano TM (2014) Smouldering fire signatures in peat and their implications for palaeoenvironmental reconstructions. Geochimica et Cosmochimica Acta 137, 134–146.
| Smouldering fire signatures in peat and their implications for palaeoenvironmental reconstructions.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2cXps12nsrs%3D&md5=43eea975a02aa38c9f9ec16ca1966828CAS |
