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  • Journal article
    Rackauskaite E, Kotsovinos P, Rein G, 2017,

    Structural response of a steel-frame building to horizontal and vertical travelling fires in multiple floors

    , Fire Safety Journal, Vol: 91, Pages: 542-552, ISSN: 1873-7226

    During previous fire events such as the World Trade Centre Towers (WTC) 1, 2 & 7 in New York (2001), the Windsor Tower in Madrid (2005), and the Plasco building in Iran (2017), flames were observed to travel horizontally across the floor plate and vertically to different floors. Such fires are not considered as part of the traditional prescriptive structural design for fire. Recently, the Travelling Fires Methodology (TFM) has been developed to account for such horizontally travelling nature of fires. A dozen of studies have investigated the structural response of steel, concrete, and composite structures to a single-floor travelling fire. 5 out of 6 of the vertically travelling fire studies have been limited to the structures with a long span composite truss system as in the WTC Towers. The aim of this work is to investigate the response of a substantially different structural system, i.e. a generic multi-storey steel frame, subjected to travelling fires in multiple floors, and varying the number of fire floors, including horizontal and vertical fire spread. A two-dimensional 10-storey 5-bay steel frame is modelled in the finite element software LS-DYNA. The number of multiple fire floors is varied between 1 and 10, and for each of these scenarios, 5 different fire types are investigated. They include four travelling fire scenarios and the standard fire. In total, 51 fire simulations are considered. The development of deflections, axial forces, bending moments and frame utilization are analysed. Results show that the largest stresses develop in the fire floors adjacent to cool floors, and their behaviour is independent of the number of fire floors. Results indicate that both the fire type and the number of fire floors have a significant effect on the failure time (i.e. exceeded element load carrying capacity) and the type of collapse mechanism. In the cases with a low number of fire floors (1–3) failure is dominated by the loss of material strength, while

  • Journal article
    Rackauskaite E, Kotsovinos P, Rein G, 2017,

    Model parameter sensitivity and benchmarking of the explicit dynamic solver of LS-DYNA for structural analysis in case of fire

    , Fire Safety Journal, Vol: 90, Pages: 123-138, ISSN: 1873-7226

    Due to the complex nature of structural response in fire, computational tools are often necessary for the safe design of structures under fire conditions. In recent years, use of the finite element code LS-DYNA has grown considerably in research and industry for structural fire analysis, but there is no benchmarking of the code available in the fire science literature for such applications. Moreover, due to the quasi-static nature of structural response in fire, the majority of the computational structural fire studies in the literature are based on the use of static solvers. Thus, this paper aims at benchmarking the explicit dynamic solver of LS-DYNA for structural fire analysis against other static numerical codes and experiments. A parameter sensitivity study is carried out to study the effects of various numerical parameters on the convergence to quasi-static solutions. Four canonical problems that encompass a range of thermal and mechanical behaviours in fire are simulated. In addition, two different modelling approaches of composite action between the concrete slab and the steel beams are investigated. In general, the results confirm that when numerical parameters are carefully considered such as to not induce excessive inertia forces in the system, explicit dynamic analyses using LS-DYNA provide good predictions of the key variables of structural response during fire.

  • Journal article
    Restuccia F, Huang X, Rein G, 2017,

    Self-ignition of natural fuels: can wildfires of carbon-rich soil start by self-heating?

    , Fire Safety Journal, Vol: 91, Pages: 828-834, ISSN: 1873-7226

    Carbon-rich soils, like histosols or gelisols, cover more than 3% of the Earth's land surface, and store roughly three times more carbon than the Earth's forests. Carbon-rich soils are reactive porous materials, prone to smouldering combustion if the inert and moisture contents are low enough. An example of soil combustion happens in peatlands, where smouldering wildfires are common in both boreal and tropical regions. This work focuses on understanding soil ignition by self-heating, which is due to spontaneous exothermic reactions in the presence of oxygen under certain thermal conditions. We investigate the effect of soil inorganic content by creating under controlled conditions soil samples with inorganic content (IC) ranging from 3% to 86% of dry weight: we use sand as a surrogate of inorganic matter and peat as a surrogate of organic matter. This range is very wide and covers all IC values of known carbon-rich soils on Earth. The experimental results show that self-heating ignition in different soil types is possible, even with the 86% inorganic content, but the tendency to ignite decreases quickly with increasing IC. We report a clear increase in ambient temperature required for ignition as the IC increases. Combining results from 39 thermostatically-controlled oven experiments, totalling 401 h of heating time, with the Frank-Kamenetskii theory of ignition, the lumped chemical kinetic and thermal parameters are determined. We then use these parameters to upscale the laboratory experiments to soil layers of different thicknesses for a range of ambient temperatures ranging from 0 °C to 40 °C. The analysis predicts the critical soil layer thicknesses in nature for self-ignition at various possible environmental temperatures. For example, at 40 °C a soil layer of 3% inorganic content can be ignited through self-heating if it is thicker than 8.8 m, but at 86% IC the layer has to be 1.8 km thick, which is impossible to find in nature. We estimate that th

  • Journal article
    Fernandez-Anez N, Christensen K, Rein G, 2017,

    Two-dimensional model of smouldering combustion using multi-layer cellular automaton: The role of ignition location and direction of airflow

    , Fire Safety Journal, Vol: 91, Pages: 243-251, ISSN: 0379-7112

    Smouldering combustion is one of the most common and persistent fire hazards of reactive porous media, such as biomass. In this work, a two-dimensional multi-layer cellular automaton has been developed to study the process of smouldering and the roles of both the ignition location and the direction of airflow for generic biomass. Three different configurations are studied: line front, with forward and opposed airflow respectively, and radial front. The first two configurations simulate ignition of one edge of the sample, while the radial front simulates ignition of a spot at the centre of the sample. The resulting spread patterns of line vs. radial front are significantly different. Furthermore, when smouldering occurs with similar characteristics, where both line front and radial front are self-sustained, the smouldering radial front has a higher growth rate than the line front. However, in the studied cases where enough oxygen is always available for oxidation, the direction of the airflow does not influence the spread of the smouldering front, and the line front with forward and opposed airflow present similar behaviour. Finally, two non-zero minimum values have been detected for self-sustained spread according to the moisture of the fuel (probability of drying) and its tendency for thermal degradation (probability of pyrolysis). This model provides a powerful but simple way of reproducing the complex dynamics of smouldering processes which can be used to investigate different scenarios.

  • Journal article
    Vermesi I, Rein G, Colella F, Valkvist M, Jomaas Get al., 2017,

    Reducing the computational requirements for simulating tunnel fires by combining multiscale modelling and multiple processor calculation

    , TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY, Vol: 64, Pages: 146-153, ISSN: 0886-7798

    Multiscale modelling of tunnel fires that uses a coupled 3D (fire area) and 1D (the rest of the tunnel) model is seen as the solution to the numerical problem of the large domains associated with long tunnels. The present study demonstrates the feasibility of the implementation of this method in FDS version 6.0, a widely used fire-specific, open source CFD software. Furthermore, it compares the reduction in simulation time given by multiscale modelling with the one given by the use of multiple processor calculation. This was done using a 1200 m long tunnel with a rectangular cross-section as a demonstration case. The multiscale implementation consisted of placing a 30 MW fire in the centre of a 400 m long 3D domain, along with two 400 m long 1D ducts on each side of it, that were again bounded by two nodes each. A fixed volume flow was defined in the upstream duct and the two models were coupled directly. The feasibility analysis showed a difference of only 2% in temperature results from the published reference work that was performed with Ansys Fluent (Colella et al., 2010). The reduction in simulation time was significantly larger when using multiscale modelling than when performing multiple processor calculation (97% faster when using a single mesh and multiscale modelling; only 46% faster when using the full tunnel and multiple meshes). In summary, it was found that multiscale modelling with FDS v.6.0 is feasible, and the combination of multiple meshes and multiscale modelling was established as the most efficient method for reduction of the calculation times while still maintaining accurate results. Still, some unphysical flow oscillations were predicted by FDS v.6.0 and such results must be treated carefully.

  • Journal article
    Restuccia F, Ptak N, Rein G, 2016,

    Self-heating behavior and ignition of shale rock

    , Combustion and Flame, Vol: 176, Pages: 213-219, ISSN: 1556-2921

    The combustion of shale, a porous sedimentary rock, has been reported at times in outcrop deposits and piles. However, the initiating event of most of these fires is unknown. It could be that, under the right conditions, shale rock undergoes spontaneous exothermic reactions in the presence of oxygen. This work studies experimentally and for the first time the self-heating behavior of shale rock. As shale has high inert content, novel diagnostics such as mass loss measurements and observation ofcharring are introduced to the self-heating ignition criteria in respect to other self-heating materials.Using field samples collected from the outcrop at Kimmeridge Bay (UK) and the Frank-Kamenetskii theory of ignition, we determine the effective kinetic parameters for two particle-size distributions of shale. These parameters are then used to upscale the results to geological deposits and mining piles of different thicknesses. We show that for fine particles, with diameter below 2 mm, spontaneous ignition is possible for deposits of thickness between 10.7 m and 607 m at ambient temperatures between -20 ᵒC and 44 ᵒC. For the same ambient temperature range, the critical thickness is in excess of 30 km for deposits made of coarse particles with diameter below 17 mm. Our results indicate that shale rock is reactive, with reactivity highly dependent on particle diameter, and that self-ignition is possible for small particles in outcrops, piles or geological deposits accidentally exposed to oxygen.

  • Journal article
    Huang X, Restuccia F, Gramola M, Rein Get al., 2016,

    Experimental study of the formation and collapse of an overhang in the lateral spread of smouldering peat fires

    , Combustion and Flame, Vol: 168, Pages: 393-402, ISSN: 0010-2180

    Smouldering combustion is the driving phenomenon of wildfires in peatlands, and is responsible for large amounts of carbon emissions and haze episodes world wide. Compared to flaming fires, smouldering is slow, low-temperature, flameless, and most persistent, yet it is poorly understood. Peat, as a typical organic soil, is a porous and charring natural fuel, thus prone to smouldering. The spread of smouldering peat fire is a multidimensional phenomenon, including two main components: in-depth vertical and surface lateral spread. In this study, we investigate the lateral spread of peat fire under various moisture and wind conditions. Visual and infrared cameras as well as a thermocouple array are used to measure the temperature profile and the spread rate. For the first time the overhang, where smouldering spreads fastest beneath the free surface, is observed in the laboratory, which helps understand the interaction between oxygen supply and heat losses. The periodic formation and collapse of overhangs is observed. The overhang thickness is found to increase with moisture and wind speed, while the spread rate decreases with moisture and increases with wind speed. A simple theoretical analysis is proposed and shows that the formation of overhang is caused by the spread rate difference between the top and lower peat layers as well as the competition between oxygen supply and heat losses.

  • Journal article
    Rackauskaite E, Rein G, 2016,

    Corrigendum to "Improved formulation of travelling fires and application to concrete and steel structures" [Structures 3 (2015) 250-260]

    , Structures, Vol: 6, Pages: 182-182, ISSN: 2352-0124
  • Journal article
    Huang X, Rein G, 2016,

    Interactions of Earth's atmospheric oxygen and fuel moisture in smouldering wildfires

    , Science of the Total Environment, Vol: 572, Pages: 1440-1446, ISSN: 0048-9697

    Vegetation, wildfire and atmospheric oxygen on Earth have changed throughout geological times, and are dependent on each other, determining the evolution of ecosystems, the carbon cycle, and the climate, as found in the fossil record. Previous work in the literature has only studied flaming wildfires, but smouldering is the most persistent type of fire phenomena, consuming large amounts of biomass. In this study, the dependence of smouldering fires in peatlands, the largest wildfires on Earth, with atmospheric oxygen is investigated. A physics-based computational model of reactive porous media for peat fires, which has been previously validated against experiments, is used. Simulations are conducted for wide ranges of atmospheric oxygen concentrations and fuel moisture contents to find thresholds for ignition and extinction. Results show that the predicted rate of spread increases in oxygen-rich atmospheres, while it decreases over wetter fuels. A novel nonlinear relationship between critical oxygen and critical moisture is found. More importantly, we show that compared to previous work on flaming fires, smouldering fires can be ignited and sustained at substantially higher moisture contents (up to 100% MC vs. 40% for 21% oxygen level), and lower oxygen concentrations (down to 13% vs. 16%). This defines a new atmospheric oxygen threshold for wildfires (13%), even lower than previously thought in Earth Sciences (16%). This finding should lead to reinterpretation of how the char remains observed in the fossil record constrain the lower concentration of oxygen in Earth's atmosphere in geological timescale.

  • Journal article
    Prat-Guitart N, Rein G, Hadden RM, Belcher CM, Yearsley JMet al., 2016,

    Effects of spatial heterogeneity in moisture content on the horizontal spread of peat fires

    , Science of the Total Environment, Vol: 572, Pages: 1422-1430, ISSN: 0048-9697

    The gravimetric moisture content of peat is the main factor limiting the ignition and spread propagation of smouldering fires. Our aim is to use controlled laboratory experiments to better understand how the spread of smouldering fires is influenced in natural landscape conditions where the moisture content of the top peat layer is not homogeneous. In this paper, we study for the first time the spread of peat fires across a spatial matrix of two moisture contents (dry/wet) in the laboratory. The experiments were undertaken using an open-top insulated box (22. ×. 18. ×. 6. cm) filled with milled peat. The peat was ignited at one side of the box initiating smouldering and horizontal spread. Measurements of the peak temperature inside the peat, fire duration and longwave thermal radiation from the burning samples revealed important local changes of the smouldering behaviour in response to sharp gradients in moisture content. Both, peak temperatures and radiation in wetter peat (after the moisture gradient) were sensitive to the drier moisture condition (preceding the moisture gradient).Drier peat conditions before the moisture gradient led to higher temperatures and higher radiation flux from the fire during the first 6. cm of horizontal spread into a wet peat patch. The total spread distance into a wet peat patch was affected by the moisture content gradient. We predicted that in most peat moisture gradients of relevance to natural ecosystems the fire self-extinguishes within the first 10. cm of horizontal spread into a wet peat patch. Spread distances of more than 10. cm are limited to wet peat patches below 160% moisture content (mass of water per mass of dry peat). We found that spatial gradients of moisture content have important local effects on the horizontal spread and should be considered in field and modelling studies.

  • Journal article
    Prat-Guitart N, Rein G, Hadden RM, Belcher CM, Yearsley JMet al., 2016,

    Propagation probability and spread rates of self-sustained smouldering fires under controlled moisture content and bulk density conditions

    , International Journal of Wildland Fire, Vol: 25, Pages: 456-465, ISSN: 1448-5516

    The consumption of large areas of peat during wildfires is due to self-sustained smouldering fronts that can remain active for weeks. We studied the effect of peat moisture content and bulk density on the horizontal propagation of smouldering fire in laboratory-scale experiments. We used milled peat with moisture contents between 25 and 250% (mass of water per mass of dry peat) and bulk densities between 50 and 150 kg m–3. An infrared camera monitored ignition, spread and extinction of each smouldering combustion front. Peats with a bulk density below 75 kg m–3 and a moisture content below 150% self-sustained smouldering propagation for more than 12 cm. Peat with a bulk density of 150 kg m–3 could self-sustain smouldering propagation up to a critical moisture content of 115%. A linear model estimated that increasing both moisture content and bulk density significantly reduced the median fire spread rate (which ranged between 1 and 5 cm h–1). Moisture content had a stronger effect size on the spread rate than bulk density. However, the effect of bulk density on spread rate depends upon the moisture content, with the largest effect of bulk density at low moisture contents.

  • Journal article
    Abbott BW, Jones JB, Schuur EAG, Chapin FS, Bowden WB, Bret-Harte MS, Epstein HE, Flannigan MD, Harms TK, Hollingsworth TN, Mack MC, McGuire AD, Natali SM, Rocha AV, Tank SE, Turetsky MR, Vonk JE, Wickland KP, Aiken GR, Alexander HD, Amon RMW, Benscoter BW, Bergeron Y, Bishop K, Blarquez O, Bond-Lamberty B, Breen AL, Buffam I, Cai Y, Carcaillet C, Carey SK, Chen JM, Chen HYH, Christensen TR, Cooper LW, Cornelissen JHC, de Groot WJ, DeLuca TH, Dorrepaal E, Fetcher N, Finlay JC, Forbes BC, French NHF, Gauthier S, Girardin MP, Goetz SJ, Goldammer JG, Gough L, Grogan P, Guo L, Higuera PE, Hinzman L, Hu FS, Hugelius G, Jafarov EE, Jandt R, Johnstone JF, Karlsson J, Kasischke ES, Kattner G, Kelly R, Keuper F, Kling GW, Kortelainen P, Kouki J, Kuhry P, Laudon H, Laurion I, Macdonald RW, Mann PJ, Martikainen PJ, McClelland JW, Molau U, Oberbauer SF, Olefeldt D, Pare D, Parisien M-A, Payette S, Peng C, Pokrovsky OS, Rastetter EB, Raymond PA, Raynolds MK, Rein G, Reynolds JF, Robards M, Rogers BM, Schaedel C, Schaefer K, Schmidt IK, Shvidenko A, Sky J, Spencer RGM, Starr G, Striegl RG, Teisserenc R, Tranvik LJ, Virtanen T, Welker JM, Zimov Set al., 2016,

    Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire: an expert assessment

    , ENVIRONMENTAL RESEARCH LETTERS, Vol: 11, ISSN: 1748-9326
  • Journal article
    Ang CDE, Rein G, Peiro J, Harrison Ret al., 2016,

    Simulating longitudinal ventilation flows in long tunnels: comparison of full CFD and multi-scale modelling approaches in FDS6

    , Tunnelling and Underground Space Technology, Vol: 52, Pages: 119-126, ISSN: 0886-7798

    The accurate computational modelling of airflows in transport tunnels is needed for regulations compliance, pollution and fire safety studies but remains a challenge for long domains because the computational time increases dramatically. We simulate air flows using the open-source code FDS 6.1.1 developed by NIST, USA. This work contains two parts. First we validate FDS6’s capability for predicting the flow conditions in the tunnel by comparing the predictions against on-site measurements in the Dartford Tunnel, London, UK, which is 1200 m long and 8.5 m in diameter. The comparison includes the average velocity and the profile downstream of an active jet fan up to 120 m. Secondly, we study the performance of the multi-scale modelling approach by splitting the tunnel into CFD domain and a one-dimensional domain using the FDS HVAC (Heating, Ventilation and Air Conditioning) feature. The work shows the average velocity predicted by FDS6 using both the full CFD and multi-scale approaches is within the experimental uncertainty of the measurements. Although the results showed the prediction of the downstream velocity profile near the jet fan falls outside the on-site measurements, the predictions at 80 m and beyond are accurate. Our results also show multi-scale modelling in FDS6 is as accurate as full CFD but up to 2.2 times faster and that computational savings increase with the length of the tunnel. This work sets the foundation for the next step in complexity with fire dynamics introduced to the tunnel.

  • Journal article
    Huang X, Rein G, 2016,

    Thermochemical Conversion of Biomass in Smouldering Combustion across Scales: the Roles of Heterogeneous Kinetics, Oxygen and Transport Phenomena

    , Bioresource Technology, Vol: 207, Pages: 409-421, ISSN: 1873-2976

    We investigate the thermochemical conversion of biomass in smouldering combustion bycombining experiments and modelling at two scales: matter (1 mg) and laboratory (100g) scales. Emphasis is put on the effect of oxygen (0 to 33 vol.%) and oxidation reactionsbecause these are poorly studied in the literature in comparison to pyrolysis. The results areobtained for peat as representative biomass supported by high-quality experimental data.Three kinetic schemes are explored, including various steps of drying, pyrolysis and oxidation.The kinetic parameters are found using the Kissinger-Genetic Algorithm method, andthen implemented in a 1D model of heat and mass transfer. The predictions are validated inthermogravimetric and bench-scale experiments to unravel the role of heterogeneous reaction.This is the first time that the influence of oxygen on biomass smouldering is explainedin terms of both chemistry and transport phenomena across scales.

  • Journal article
    Vermesi I, Roenner N, Pironi P, Hadden R, Rein Get al., 2016,

    Pyrolysis and ignition of a polymer by transient irradiation

    , Combustion and Flame, Vol: 163, Pages: 31-41, ISSN: 0010-2180

    Pyrolysis is the thermochemical process that leads to the ignition of a solid fuel and a key mechanism in flame spread and fire growth. Because polymer materials are flammable and ubiquitous in the modern environment, the understanding of polymer pyrolysis is thus essential to tackle accidental fires. In this paper, we used transient irradiation as an external source of heat to study the process of pyrolysis and ignition of a polymer sample. While previous ignition studies use constant irradiation, transient irradiation is the most frequent condition found in accidental fires, but it lacks a theoretical framework since it has been largely ignored in the literature. Moreover, transient irradiation is a more comprehensive case for the understanding of pyrolysis where nonlinear heat transfer effects challenge the validity of solid-phase criteria for flaming ignition developed previously. We propose here that transient irradiation is the general problem to solid fuel ignition of which constant irradiation is a particular solution. In order to investigate how this novel heat source inuences polymer pyrolysis and flammability, numerical simulations and experiments have been conducted on Poly(methyl methacrylate) (PMMA) samples 100mm by 100mm and 30mm deep exposed to a range of parabolic pulses of irradiation. The 1D model, coded in GPyro, uses heat and mass transfer and single-step heterogeneous chemistry, with temperature dependent properties. The predictions are compared to experiments conducted in the Fire Propagation Apparatus using both constant and transient irradiation conditions. The experiments validate the temperature predictions of the model and also provide the time to ignition. The model then complements the experiments by calculating the mass loss rate. A series of 16 parabolic pulses (including repeats) are investigated with a range of peak irradiation from 25 to 45 kW/m2, while the time to peak ranges from 280 to 480s. For these pulses, the time to igniti

  • Book
    Stracher GB, Prakash A, Rein G, 2016,

    Preface to Volume 4

    , ISBN: 9780444595126
  • Book
    Stracher GB, Prakash A, Rein G, 2016,

    Coal and Peat Fires: A Global Perspective Volume 4: Peat - Geology, Combustion, and Case Studies

    , ISBN: 9780444595126

    Coal and Peat Fires: A Global Perspective, Volumes 1–4, presents a fascinating collection of research about prehistoric and historic coal and peat fires. Magnificent illustrations of fires and research findings from countries around the world are featured—a totally new contribution to science. This last of four volumes in the collection, Peat--Geology, Combustion, and Case Studies, examines in detail peat fires chronicled in several countries. In addition, the geology of peat, peat megafires, infrared analysis of fires, and the mathematical modelling of fire hazards are presented. This essential reference includes a companion website with an interactive world map of coal and peat fires, collections of slide presentations, research data, additional chapters, and videos: booksite.elsevier.com/9780444595102.

  • Book chapter
    Rein G, 2016,

    Smoldering Combustion

    , SFPE Handbook of Fire Protection Engineering, Publisher: Springer, Pages: 581-603, ISBN: 978-1-4939-2564-3

    Smoldering combustion is the slow, low temperature, flameless burning of porous fuels and is the most persistent type of combustion phenomena. It is especially common in porous fuels which form a char on heating, like cellulosic insulation, polyurethane foam or peat. Smoldering combustion is among the leading causes of residential fires, and it is a source of safety concerns in industrial premises as well as in commercial and space flights. Smoldering is also the dominant combustion phenomena in megafires in natural deposits of peat and coal which are the largest and longest burning fires on Eartht.

  • Journal article
    Wang S, Huang X, Chen H, Liu N, Rein Get al., 2015,

    Ignition of low-density expandable polystyrene foam by a hot particle

    , Combustion and Flame, Vol: 162, Pages: 4112-4118, ISSN: 0010-2180

    Insulating materials are ubiquitous in modern buildings for improving energy efficiency, but their high flammability becomes a significant fire safety issue. Many large fires in high-rise buildings were caused by the ignition of insulating materials by hot particles from fireworks and welding processes. Such ignition event is fundamentally different from the traditional flame or radiation driven ignition assumed in the literature, and still presents significant knowledge gaps. In this work, we study experimentally the ignition of a widely used insulation materials, expandable polystyrene (EPS) foam, by a hot steel particle under different conditions. In the experiments, a small spherical particle (6∼14 mm in diameter) was heated to a high temperature (>900 °C), and then placed on a bench-scale low-density (18 or 27 kg/m3) foam sample. It was observed that flaming ignition could only occur on the foam surface during its rolling process (rolling ignition) or before it was fully embedded (embedding ignition). The measurements suggested that larger particles held lower critical temperatures for ignition, which decreased from 1030 to 935 °C for diameters increasing from 6 to 14 mm. Compared to higher-density forest fuels in the literature, the critical particle temperature of EPS foam is much higher, with a narrower transition region for ignition probability of 5–95% and has a weaker dependence on the particle size. Results also show that both the sample density and thickness have a negligible influence on the ignition probability and mass-loss ratio. Theoretical analysis suggested that the hot particle acts as both heating and pilot sources, and the ignition of EPS foam is controlled by the competition between the gas mixing time and the particle residence time.

  • Book chapter
    Prat-Guitart N, Hadden RM, Belcher CM, Rein G, Yearsley JMet al., 2015,

    Infrared Image Analysis as a Tool for Studying the Horizontal Smoldering Propagation of Laboratory Peat Fires

    , Coal and Peat Fires: A Global Perspective, Pages: 121-139, ISBN: 9780444595102

    Smoldering fires in peatlands can consume large areas of peat and release important amounts of carbon to the atmosphere as they self-propagate. This chapter focuses on the use of infrared images to characterize the horizontal propagation of smoldering fires in laboratory experiments. In these laboratory experiments an infrared camera takes images of the peat surface at regular intervals during the experiment. We present methods to process and analyze these infrared images that identify the shape and position of the smoldering front, quantify the maximum energy flux, the spread rate and direction of the front and its variability to time. To demonstrate our methods we analyze images from experiments that record the smoldering of dry peats (25% moisture content, mass of water per mass of dry peat) and wet peats (100% moisture content). Infrared images are used to quantify the effect of moisture content upon the smoldering fronts. Our methods demonstrate that smoldering combustion in dry peats has a wider front (6.8 ± 1 cm for the dry peat, 2.4 ± 0.7 cm for the wet peat), a faster spread rate (4.3 ± 1 cm/h for dry peat, 2.6 ± 0.7 cm/h for wet peat), and a lower peak of radiative energy flux (7.1 ± 0.7 kW/m2 for dry peat, 10.51 ± 2.1 kW/m2 for wet peat). Our infrared image analysis is a useful tool to characterize peat fires at an experimental scale. These methods can be applied to peats with different characteristics to identify and compare smoldering propagation dynamics.

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