Academic literature on the topic 'Smouldering combustion'
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Journal articles on the topic "Smouldering combustion"
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Irfan Pratantyo, Gatot Prayogo, Agus Sunjarianto Pamitran, and Yulianto Sulistyo Nugroho. "Thermal Imaging Study on The Effect of Permeability on Smouldering Behaviour of a Tropical Peat." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 89, no. 1 (December 5, 2021): 154–59. http://dx.doi.org/10.37934/arfmts.89.1.154159.
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Smouldering is a slow-burning, low-temperature, flameless combustion, and frequently happens in peatland fires. The smouldering spread occurs because of the parameter achievement in oxygen supply, generated heat, and heat released to the environment. The condition of porous and fibrous peat soils makes oxygen supply easily happens. The difficulty of getting to the location of the burning peatland is one of the problems to extinguish the fire. This study aims to observe with thermal imaging study the effect of peat permeability on smouldering behaviour of a tropical peat sample. Mechanical compaction was applied to reduce permeability and pore value in the central of the peat soil. Then, peat soil is ignited to create the smouldering propagation through the compacted peat area. The combustion process that occurs on the surface is observed by a visual camera and an Infrared FLIR Thermal Camera. The initial results showed a reduction in the smouldering spread rate on the compacted soil region as compared to the undisturbed peat smouldering region. Nevertheless, smouldering combustion of peat still occurred in all regions of the reactor, once the smouldering front could penetrate the compacted region.
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Xifré-Salvadó, Miquel Àngel, Núria Prat-Guitart, Marcos Francos, Xavier Úbeda, and Marc Castellnou. "Smouldering Combustion Dynamics of a Soil from a Pinus halepensis Mill. Forest. A Case Study of the Rocallaura Fires in Northeastern Spain." Applied Sciences 10, no. 10 (May 16, 2020): 3449. http://dx.doi.org/10.3390/app10103449.
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This study analyses the smouldering combustion on soils that took place during the wildfires that occurred in Rocallaura (Northeastern Spain). The smouldering combustion after the first event, 23 June, was the potential source of flaming fire re-ignition of the second event, 19 July 2016. Re-ignitions are an important challenge for the firefighting system. Budget and efforts are spent on controlling these re-ignitions that can ultimately cause the collapse of the response system if the re-ignitions happen during periods of simultaneous fire events. Our objective is to contribute to better understand the dynamics of the smouldering combustion of organic soils associated with these wildfires and the impact on the Pinus halepensis Mill. forest ecosystem. Transects were established in adjacent control and post-fire zones. Laboratory analyses were conducted to determine some physical and chemical properties of both the duff and mineral soil. Using these variables, we estimate thresholds of duff ignition probability, percentage of duff consumption and smouldering combustion spread rates. Overall, we provide a set of tools for evaluating re-ignitions in forest ecosystems. We conclude that the concept of fire persistence should be a new variable for consideration in present and future analysis of fire regimes and demonstrates the significance of introducing smouldering combustion and re-ignition within the strategic framework of the wildfire hazard and integrating these phenomena into forest planning and management.
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Pastor, E., I. Oliveras, E. Urquiaga-Flores, J. A. Quintano-Loayza, M. I. Manta, and E. Planas. "A new method for performing smouldering combustion field experiments in peatlands and rich-organic soils." International Journal of Wildland Fire 26, no. 12 (2017): 1040. http://dx.doi.org/10.1071/wf17033.
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Smouldering ground fires have severe environmental implications. Their main effects are the release of large amounts of carbon to the atmosphere with loses of organic soil and its biota. Quantitative data on the behaviour of smouldering wildfires are very scarce and are needed to understand its ecological effects, to validate fuel consumption and smouldering propagation models and to develop danger-rating systems. We present, for the first time, a methodology for conducting smouldering experiments in field conditions. This method provides key data to investigate smouldering combustion dynamics, acquire fire behaviour metrics and obtain indicators for ecological effects of smouldering fires. It is to be applied in all types of undisturbed soils. The experimental protocol is based on a non-electric ignition source and the monitoring system relies on combining both point and surface specific temperature measurements. The methodology has been developed and applied by means of large series of replicate experiments in highly organic soils at the forest–grassland treeline of the Peruvian Andes. The soil tested exhibited weak ignition conditions. However, transition to oxidation phase was observed, with smouldering combustion during 9 h at 15-cm depth and residence times at temperatures above dehydration of ~22 h.
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Reardon, James, Roger Hungerford, and Kevin Ryan. "Factors affecting sustained smouldering in organic soils from pocosin and pond pine woodland wetlands." International Journal of Wildland Fire 16, no. 1 (2007): 107. http://dx.doi.org/10.1071/wf06005.
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The smouldering combustion of peat and muck soil plays an important role in the creation and maintenance of wetland communities. This experimental study was conducted to improve our understanding of how moisture and mineral content constrain smouldering in organic soil. Laboratory burning was conducted with root mat and muck soil samples from pocosin and pond pine woodland wetlands common on the North Carolina coastal plain. The results of laboratory and prescribed burning were compared. Laboratory results showed that moisture and mineral content influenced sustained smouldering in root mat soils. Predictions based on logistic regression analysis show that root mat soils with an average mineral content of 4.5% had an estimated 50% probability of sustained smouldering at a moisture content of 93%, whereas at moisture contents above 145% the estimated probability was less than 10%. The odds that root mat soil will sustain smouldering decrease by 19.3% for each 5% increase in moisture content. Root mat soils with an average mineral content of 5.5% and a moisture content of 93% had an estimated 61% probability of sustained smouldering. The odds that root mat soil will sustain smouldering combustion increased by 155.9% with each 1% increase in mineral content. Root mat and muck soils differ in physical and chemical characteristics expected to influence smouldering behaviour. The formation of muck soil has led to increases in density, smaller soil particle size, changes in water holding characteristics and increases in waxes, resins and bituminous compounds. Muck soil smouldered at higher moisture contents than root mat soil. Muck soil at a moisture content of 201% had an estimated 50% probability of sustained smouldering, whereas at moisture contents above 260% the estimated probability was less than 10%. The odds that muck soil will sustain smouldering combustion decrease by 17.2% with each 5% increase in moisture content. Ground fire in the prescribed burns stopped its vertical spread in organic soils at moisture contents consistent with logistic regression predictions developed from our laboratory results.
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Ordou, Niloofar, and Igor E. Agranovski. "Contribution of Fine Particles to Air Emission at Different Phases of Biomass Burning." Atmosphere 10, no. 5 (May 16, 2019): 278. http://dx.doi.org/10.3390/atmos10050278.
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Particle size distribution in biomass smoke was observed for different burning phases, including flaming and smouldering, during the combustion of nine common Australian vegetation representatives. Smoke particles generated during the smouldering phase of combustions were found to be coarser as compared to flaming aerosols for all hard species. In contrast, for leafy species, this trend was inversed. In addition, the combustion process was investigated over the entire duration of burning by acquiring data with one second time resolution for all nine species. Particles were separately characterised in two categories: fine particles with dominating diffusion properties measurable with diffusion-based instruments (Dp < 200 nm), and coarse particles with dominating inertia (Dp > 200 nm). It was found that fine particles contribute to more than 90 percent of the total fresh smoke particles for all investigated species.
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Seng, T. H., S. Suratman, M. R. Abas, and N. M. Tahir. "Emission of Polycyclic Aromatic Hydrocarbons in Smoke Particulates at Three Different Combustion Stages from Burning of Rhizophora apiculate, Melaleuca leucadendron and Hevea brasiliensis Wood." Asian Journal of Chemistry 33, no. 4 (March 20, 2021): 892–96. http://dx.doi.org/10.14233/ajchem.2021.23125.
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The purpose of this study was to characterize and determine the concentrations of polycyclic aromatic hydrocarbons (PAHs) emitted in smoke particulates from burning of Rhizophora apiculata, Melaleuca leucadendron and Hevea Brasilensis at the smouldering, flaming and charring stages. Smoke particulates were sampled using a total suspended particulate Hi-volume sampler (HVS) at a rate of 1.13 m3/min and PAHs were extracted with a mixture of dichloromethane-methanol (3:1 v/v) using ultrasonic agitation. Fractionation of PAHs was carried out on an alumina-silica column and analysis by gas chromatography-mass spectrometry (GC-MS). The results showed that most of the samples exhibited the highest total identified PAHs in the smouldering stage with formation of PAHs with three rings or more increasing from the smouldering to flaming stages and reducing as combustion entered the charring stage. Naphthalene, phenanthrene and pyrene were the dominant PAHs detected in the wood smoke particulates, depending on combustion stage. Overall the emission and formation of PAHs are strongly dependent on combustion stage as well as other factors such as wood morphology, species, moisture content and combustion temperature.
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Garg, Priya, Thomas Roche, Matthew Eden, Jacqueline Matz, Jessica M. Oakes, Chiara Bellini, and Michael J. Gollner. "Effect of moisture content and fuel type on emissions from vegetation using a steady state combustion apparatus." International Journal of Wildland Fire 31, no. 1 (October 5, 2021): 14–23. http://dx.doi.org/10.1071/wf20118.
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Emission measurements are available in the literature for a wide variety of field burns and laboratory experiments, although previous studies do not always isolate the effect of individual features such as fuel moisture content (FMC). This study explores the effect of FMC on gaseous and particulate emissions from flaming and smouldering combustion of four different wildland fuels found across the United States. A custom linear tube-heater apparatus was built to steadily produce emissions in different combustion modes over a wide range of FMC. Results showed that when compared with flaming combustion, smouldering combustion showed increased emissions of CO, particulate matter and unburned hydrocarbons, corroborating trends in the literature. CO and particulate matter emissions in the flaming mode were also significantly correlated with FMC, which had little influence on emissions for smouldering mode combustion, when taking into account the dry mass of fuel burned. These variations occurred for some vegetative fuel species but not others, indicating that the type of fuel plays an important role. This may be due to the chemical makeup of moist and recently live fuels, which is discussed and compared with previous measurements in the literature.
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Sofan, P., G. A. Chulafak, A. I. Pambudi, and F. Yulianto. "Assessment of space-based tropical smouldering peatlands: mixed pixel analysis." IOP Conference Series: Earth and Environmental Science 1109, no. 1 (November 1, 2022): 012054. http://dx.doi.org/10.1088/1755-1315/1109/1/012054.
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Abstract Detection of tropical smouldering peatlands from space remains a challenge in a mixed pixel issue. This study aims to discriminate the mixed pixel containing smouldering fire resulting from Tropical Peatland Combustion Algorithm (ToPeCAl) applied to Landsat-8. The assessment of the smouldering pixel was conducted by applying a modification of the contextual test to select the smouldering pixel and then proceed it to linear spectral mixture analysis. The smouldering and burnt areas used for endmembers were determined from field observation. Our study areas span from South to West Kalimantan’s peatlands covering six path-rows of Landsat-8 in the fire seasons of 2018-2019. There were 53,224 candidate smouldering pixels from ToPeCAl which 80% of them passed the contextual test. Based on mixed pixel analysis, most of the selected smouldering pixels consisted of more than 0.79 of smouldering fraction. This was confirmed by the smoke features on the ground from the high spatial PlanetScope images acquired on the same day with Landsat-8. The actual false alarms pixel may consist of 0.74 of smouldering fraction and more than 0.20 of the burnt area or vegetated area fraction with no smoke features on the ground. Further research on smoke mapping or aerosol properties over burning peatland could enhance the performance of smouldering pixel detection.
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HERBERT, D. M., C. E. KERR, and J. ADLER. "DIFFUSION-CONTROLLED SMOULDERING COMBUSTION WITH MATERIAL SHRINKAGE." Quarterly Journal of Mechanics and Applied Mathematics 47, no. 1 (1994): 43–52. http://dx.doi.org/10.1093/qjmam/47.1.43.
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Alexopoulos, S., and D. D. Drysdale. "The transition from smouldering to flaming combustion." Fire and Materials 13, no. 1 (March 1988): 37–44. http://dx.doi.org/10.1002/fam.810130106.
Full textDissertations / Theses on the topic "Smouldering combustion"
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Scott, Kathleen. "The smouldering of peat." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/the-smouldering-of-peat(a763e5eb-3928-4640-83e1-abe660ac3922).html.
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A model examining underground smouldering peat combustion is presented. A one-step chemical reaction is considered where the gas and solid are assumed to be in thermal equilibrium. The full model allows porosity, permeability and gas density to vary and considers a buoyant velocity field determined by Darcy's law. Due to the low bulk thermal conductivity of peat, the diffusion of oxygen through it is characterised by a Lewis number much less than one. This results in thermal-diffusive instabilities. These instabilities can cause flame balls to arise in gaseous combustion and a fingering regime to arise in solid combustion. Analytical solutions to simplified spherically symmetrical equations are derived. These equations assume diffusion to be the dominant transport mechanism as well as taking that the porosity, gas molecular weight and gas density all remain constant. The underlying structure of the combustion region is found to be analogous to that of a flame ball. When studied in cylindrical symmetry a single, stable finger can be modelled propagating against an imposed air flow. The effects of heat losses, velocity magnitude and the Lewis number can be studied and results are compared to existing experimental smouldering combustion data. Although no detailed experiments have studied this phenomenon in peat, predicted results capture key qualitative trends found in both filtration combustion of polyurethane foam and in the fingering combustion of paper. In addition to this, when the imposed air flow is reduced to zero a propagating combustion front is predicted, analogous to a self-travelling flame ball. When the velocity field is determined by Darcy's law the dimensionless permeability of the peat plays a key role in determining the range of values over which fingering combustion can occur. Whilst there is little impact of taking the gas molecular weight to be constant, when porosity is allowed to vary and a relationship between porosity and permeability is included an over-blowing extinction limit is identified. This limit is not found in the constant-porosity model where a low-fuel extinction limit is predicted. Peats of differing ages and locations can possess significantly different characteristics. However, the fingering regime is predicted to occur within the range of parameters in which peat soils lie. Experiments suggest that fingering combustion can take the form of both sparse fingers and a complex fingering regime. The cylindrically symmetrical model can not capture tip-splitting. Hence the model does not explicitly account for the distance between two neighbouring fingers. However, an estimate for this value can be made if peat smouldering were to occur in a regime of multiple fingering. An averaged continuum model describing the spread of an ember storm is also presented. The dominant mechanism determining the spread-rate of the fire is the lofting and landing of embers and individual fires are taken to grow in an elliptical manner under the influence of the wind. When an ember storm is spreading at a steady speed, its spread rate is found to be described by a single similarity solution.
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Huang, Xinyan. "Fundamental study of smouldering combustion of peat in wildfires." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/30789.
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Smouldering combustion is the slow, low-temperature, flameless burning of porous fuels and the most persistent type of combustion, different from flaming combustion. Smouldering is the dominant phenomena in fires of coal and natural deposits of peat which are the largest and longest burning fires on Earth. These megafires fires contribute considerably to annual greenhouse gas emissions roughly equivalent to 15% of the man-made emissions, and result in the widespread destruction of global ecosystems and regional haze events. Moreover, the atmospheric release of ancient carbon in soil and the sensitivity of peat ignition to higher temperatures and drier conditions create a positive feedback mechanism to climate change. Compared to flaming combustion, smouldering combustion can be initiated with a much weaker ignition source, and provide a hazard shortcut to flaming. Once ignited, the persistent smouldering fires can consume a huge amount of earth biomass, and burn for very long periods of time (days, years and centuries) despite extensive firefighting efforts or climate changes. For the past few decades, there have been some experimental studies on smouldering peat fires of different scales. However, very few computational work has been done to systematically study such emerging fire phenomena before the research undertaken in this thesis. This thesis is presented in a manuscript style: each chapter takes the form of an independent paper, which has been published or submitted to a journal publication. A final chapter summarizes the conclusions, and suggests potential areas of future research. Chapter 1 first proposes a comprehensive 5-step kinetic model based on thermogravimetric analysis (TGA) to describe the heterogeneous reactions in smouldering combustion of peat. The corresponding kinetic parameters are inversely modelled using genetic algorithm (GA). This 5-step (including drying) kinetic model successfully explains the TG data of four different peat soils from different geographical locations. The chemical validity of the scheme is also investigated by incorporating it into a one-dimensional (1-D) plug-flow model. The reaction and species distributions of two most common fire spread modes, lateral and in-depth spread, are successfully simulated. Chapter 2 presents a new comprehensive 1-D model of a reactive porous media to solve the conservation equations and the proposed 5-step heterogeneous chemical kinetics. This model is used to simulate several ignition experiments on bench-scale peat samples in the literature. The model first predicts the smouldering thresholds, relating to the critical moisture content (MC) and inert content (IC). The modelling results show a good agreement with experiments for a wide range of peat types and organic soils. The influences of the kinetic parameters, physical properties, and ignition protocol on initiating the peat fire are also investigated. Chapter 3 continues to optimize this 1-D model to investigate the vertical in-depth spread of smouldering fires into peat columns 20-30 cm deep with heterogeneous profiles of MC, IC and density. Modelling results reveal that smouldering combustion can spread over peat layers with a very high MC (~250%) if the layer is thin and located below a thick and drier layer. It is also found that the critical MC for extinction can be much higher than the previously reported critical MC for ignition. Furthermore, depths of burn (DOB) in peat fire is successfully predicted, and shows a good agreement with experiments on 18 field peat samples in the literature. Chapter 4 further looks into the kinetic schemes of different complexities to explain the TGA of two peat soils under various atmospheric oxygen concentration. Their best kinetic parameters are fast searched via Kissinger-genetic algorithm (K-GA) method, and the oxidation model is determined for the first time. Then, the kinetic model is applied into the 1-D model to simulate the peat experiment with fire propagation apparatus (FPA) in the literature. Try peat samples are used to minimize the influence of moisture, and ignited under both sub- and super-atmospheric oxygen concentration. Modelling results show a good agreement with experiment, and the stochastic sensitivity analysis is used to test the model sensitivity to multiple physicochemical properties. Chapter 5 investigates the interactions of atmospheric oxygen and fuel moisture in smouldering wildfires with the proposed 1-D model. Modelling results reveal a nonlinear correlation existing between the critical fuel moisture and atmospheric oxygen as MC increases, a greater increase in oxygen concentration is required for both ignition and fire spread. Smouldering fires on dry fuel can survive at a substantially lower oxygen concentration (~11%) than flaming fires, and fuel type and chemistry may play important roles especially in high MC. The predicted spread rate of smouldering peat fire is on the order of 1 mm/min, much slower than flaming fires. In addition, the rate of fire spread increases in an oxygen-richer atmosphere, while decreases over a wetter fuel. Chapter 6 presents an experimental study on smouldering fires spreading over bench-scale peat samples under various moisture and wind conditions. The periodic 'overhang' phenomenon is observed where the smouldering fire spreads beneath the top surface, and the overhang thickness is found to increase with peat MC and the wind speed. Experimental results show that the lateral spread rate decreases with MC, while increases with the wind speed. As peat MC increases, the fire spread behaviour becomes less sensitive to the wind condition and its depth. A simple heat transfer analysis is proposed to explain the influence of moisture and wind on the spread rate profile, and suggests that the overhang phenomena is caused by the spread rate difference between the top and the lower peat layers. Chapter 7 summarizes the research of this thesis, and discuss the possible areas for future research.
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Wang, Junbo. "Smouldering combustion of biosolids from wastewater treatment plants (WWTPs)." Thesis, Wang, Junbo (2017) Smouldering combustion of biosolids from wastewater treatment plants (WWTPs). Honours thesis, Murdoch University, 2017. https://researchrepository.murdoch.edu.au/id/eprint/40482/.
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The management of biosolids, the major by-product from wastewater treatment plants (WWTPs), exists as a main global challenge which takes up most of WWTP operating costs. Self-sustaining smouldering is a new method for organic waste treatment, where the waste (i.e., biosolids) is destroyed in an energy efficient way after mixing it with porous medium (i.e., sand). Column experiments, utilising biosolids generated from a WWTP, were used to detect whether smouldering combustion was able to be utilized for biosolids treatment or not. According to the peak tempertures of thermocouples obtained from the experiments, it can be identified whether the smouldering reactions are self-sustaining (SS) or non-self-sustaining (NSS). In addition, the average front velocity (AFV) can be calculated then. In this study, Self-sustaining Treatment for Active Remediation applied ex-situ (STARx) refers to the commercial technology which utilizes smouldering combustion to destroy organic wastes (i.e., biosolids). An economic consideration would be completed to estimate the expected payback period and cost savings for considering STARx as a biosolids treatment retrofit in a large WWTP in Australia. The cost savings and payback period concerning replacing either landfill or incineration were considered as these are the most popular disposals for biosolids treatment. Finally, it is obtained that STARx is a good option to be employed in the WWTPs which have employed typical disposal methods (e.g., landfill and incineration) for recent decades.
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Pironi, Paolo. "Smouldering combustion of organic liquids in porous media for remediating NAPL-contaminated soils." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/3222.
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This research investigated the potential of smouldering combustion to be employed as a remediation approach for soil contaminated by non-aqueous phase liquids (NAPLs). Small-scale (~15 cm), proof-of-concept experiments were the first to demonstrate that organic liquids embedded within an inert soil matrix can be successfully smouldered. Intermediate-scale (~30 cm) column experiments examined in detail the behaviour of the combustion process including its relationship to mass and energy balance and the evolution of temperature profiles. In addition, detailed evaluations of environmental parameters (e.g., soil concentrations, gas emissions) were conducted. For the first time, it was demonstrated that NAPL smouldering combustion can be self-sustaining (i.e., propagation of the smouldering front after termination of the igniter) and self-terminating (i.e., natural extinction of the reaction after all of the NAPL is destroyed). More than 30 column sensitivity experiments quantified the broad range of process parameters - including contaminant type, contaminant mass, soil type, and oxidizer flow rates - within which the process was self-sustaining and essentially complete remediation was achieved (i.e. contaminant mass removal in excess of 99.5%). Maximum burning temperatures were observed in the range 600-1100 C. Average propagation velocities varied between 0.7e-4 and 1.2e-4 m/s. Intensity and velocity of the process were shown to be controlled by the rate at which oxidizer is delivered. Contaminant type and mass was observed to affect peak temperatures and propagation velocity by influencing the energy balance at the reaction front. Moreover, mass and energy balance models were demonstrated to provide reasonable predictions of the observed propagation velocities. Overall, this research introduced an entirely new approach to the remediation of NAPL-contaminated soils and, further, advanced the understanding of the mechanisms that control the underlying process of smouldering combustion of liquids.
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Gustafsson, Sara, and Stina Jonsson. "Performance of cavity barriers exposed to fire : A model scale test." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-63648.
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To build multi story buildings out of timber is of a common interest in the building sector. Timber as a building material has many profits, such as the low cost, the availability and the ability to recycle it, the low carbon footprint and the workability. Although, when it comes to fire protection of buildings with a timber based structure there are challenges regarding prevention of the spread of fire while timber surface is exposed to fire. There have been cases in which timber buildings have caught fire leading to severe fire spread and ruined buildings. One example concerns a student modulus accommodation in Luleå that caught fire in august 2013. The fire started on the fourth floor after which a vertical fire spread occurred in concealed spaces between the volume modules. According to the fire investigation lack of knowledge regarding performance of detailed building solutions has led to the poor fire performance of the building. This master thesis mainly consists of a model scale tests that is prepared and performed according to the standard EN 1363-1. The purpose of the test is to investigate the performance of various cavity barriers exposed to fire. The main objective is to examine which temperatures that can be expected at different positions at various cavity barriers when using model scale test as a test method. There are two main kinds of cavity barriers: barriers that are airtight and closed inside the voids of the construction; and ventilated barriers. The most common cavity barriers are the ones that are airtight and closed. The material can be solid wood, gypsum board or mineral wool. The installation areas for these cavity barriers are anywhere, besides where the concealed spaces shall be ventilated and in every joint that shall be sealed using sealant. The ventilated cavity barriers are mounted in concealed spaces where the ventilating function is provided. These concealed spaces are often situated in, for example, ventilated attics, facades and roofs. The purpose of the ventilated barriers is to maintain the air flow in the cavity during regular conditions but also to form a protecting barrier between fire compartments when exposed to fire. The model scale test includes test apparatuses such as thermocouples and a fire resistance furnace with plate thermometers and burners. In addition, a test rig consisting of test specimens and the products to be tested are essential. In this report, two model scale tests have been performed and prepared according to EN 1363‑1. The test period endured for four hours and the thermocouples measured the temperatures during the whole time. During the first hour the test specimens were exposed to the standard ISO 834 fire curve by controlling the burners in the furnace. After one hour the burners were turned off and the specimens were no longer exposed to fire. The measurements of the temperatures continued during three more hours. After the first two of these three hours the furnace was opened to confer more oxygen in the purpose to record any changes in the temperatures. Results of the performed experiments have indicated parameters that affect the performance of the cavity barriers. The cavity surface itself has an influence to the fire spread. The number of barriers in the cavity and the material properties of the material that is used as the cavity barrier lead to the different protection by those cavity barriers. Some of the tested barriers were plastic covered, which had effect on the performance of the cavity barriers. The dimensions of the barriers, moreover the width and the thickness, are important parameters for the proper function of the barrier. The test results indicate that glowing combustion occurs in the cavity between various cavity barriers. It can be seen that the temperature rises when the furnace is opened. This indicates the appearance of smouldering since the combustion increases when the amount of oxygen increases, which leads to a temperature rise. Furthermore, the appearance of smouldering (glowing combustion) can be indicated by the observation of the damages of the specimens after the test. The temperatures that may be expected at the unexposed side of the cavity barrier depend on the surface material of the cavity, dimensions, and the material of the cavity barriers. Smouldering is a consequence of the temperature rise in closed cavities between cavity barriers. The performed test endured for approximately four hours and this indicates that fires in cavities can stay for a long time. To ensure the performance of various cavity barriers and verification by a model scale test it is important to perform further experiment and analyses to investigate the effects of the various parameters. To ensure the effectiveness of the performance of the cavity barriers they should be tested in cavities with various widths and various heights. Further investigation of the risk for smouldering is needed with measuring the amount of oxygen and the pressure.
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MAIOLI, A. G. "CFD OpenFOAM: Implementação da Combustão Smouldering e sua Avaliação Paramétrica." Universidade Federal do Espírito Santo, 2016. http://repositorio.ufes.br/handle/10/9737.
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Previous issue date: 2016-09-30A combustão smouldering é uma forma de combustão lenta, sem chama e que ocorre a relativamente baixas temperaturas. Ela é sustentada pelo calor liberado em reações heterogêneas decorrentes do ataque direto de oxigênio na superfície de combustíveis sólidos. Apesar das características relativamente baixas desse tipo de combustão, ela apresenta um perigo significativo. Este trabalho teve o objetivo de avaliar a combustão smouldering do xisto betuminoso em uma célula de combustão. Para isso foi utilizado o software de simulação gratuito OpenFOAM, com o solver biomassGasificationFoam, destinado à processos de conversão termoquímica de combustíveis sólidos em leito fixo. Os resultados foram comparados com dados experimentais da literatura. Os perfis de temperatua simulados apresentaram boa concordância com os experimentos, além de que foi possível a confirmação da estrutura de combustão reaction leading, onde a zona de reação avança de forma mais rápida do que a zona de transferência de calor. Foi avaliado também a importânica do fornecimento de oxigênio na velocidade de propagação da frente de chama, confirmando que esse parâmetro governa essa velocidade. Por fim, foi realizado um estudo paramétrico para avaliar a influência de parâmetros físicos na evolução da temperatura do leito e na velocidade de propagação da frente de chama.
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ABREU, C. E. S. "COMBUSTÃO Smouldering: Influência da Umidade e da Configuração do Leito no Tratamento Termoquímico do Lodo de Esgoto." Universidade Federal do Espírito Santo, 2015. http://repositorio.ufes.br/handle/10/9793.
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Previous issue date: 2015-07-28A necessidade da busca por fontes alternativas de energia que auxiliem na geração energética associada ao processamento térmico de algum produto de maneira sustentável ou racionalizada é um assunto de extrema importância. Além disso, com o fator ambiental que após a lei nº 12.305/10 de destinação de resíduos sólidos, a qual prevê a redução na geração de resíduos urbanos o gerenciamento de resíduos torna-se condição incontornável na gestão ou implantação de qualquer sistema ou processo. Tendo em vista essa demanda, o Lodo de Fossa Séptica (LFS) é utilizado nesse trabalho com o intuito de realizar uma análise referente ao potencial de geração de energia, e, ao mesmo tempo, sugerindo um modo auto-sustentável de tratamento termoquímico visando a redução do seu volume. Portanto, a influência da umidade do material e do tipo de configuração do leito de combustão (co-corrente ou contra-corrente) foi estudada. Inicialmente, foi realizada uma análise do poder calorífico superior (PCS) do lodo em função da sua umidade, e os resultados obtidos mostraram que para uma redução da umidade de 20% até que o lodo esteja completamente seco, ou seja, a 0%, o PCS elevou-se de 7487 até 8480 kJ.kg-1, o que representa um aumento de, aproximadamente, 14% no potencial energético do LFS. Em seguida, foi realizada a análise da combustão smouldering contra-corrente do lodo em função da umidade. Tal análise mostrou que a redução da umidade acarreta no aumento da temperatura máxima obtida no processo (962 até 1026°C) e, além disso, gera um aumento da velocidade de propagação da frente de combustão, de 2,43 até 2,99 mm.min-1. A análise referente ao processo co-corrente apresentou resultados similares, de forma que, com a redução da umidade elevou-se a temperatura máxima de operação e a velocidade de propagação da frente de combustão. Finalmente, comparou-se os resultados do processo contra-corrente e co-corrente, apontando que para o mesmo teor de umidade, o processo co-corrente apresentou maiores temperaturas e menores velocidades de propagação da frente de combustão. Paralelamente às análises supracitadas, foi verificado o teor de material inerte no lodo comparando a massa da amostra antes e após o experimento. Todos os ensaios apresentaram teor próximo de 52% de matéria inerte.
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PRETTI, J. N. "ESTUDO Benchmarking do Cfd Gratuito Openfoam na Modelagem e Simulação da Transferência de Calor em Não-equilíbrio Térmico Local e Transiente Numa Frente de Combustão Smouldering." Universidade Federal do Espírito Santo, 2015. http://repositorio.ufes.br/handle/10/9796.
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Previous issue date: 2015-08-31Com o constante aumento da demanda energética é necessário o estudo de fontes alternativas de energia bem como técnicas para sua conversão em trabalho útil em diferentes escalas de consumo. Outro fator importante é que a humanidade esta produzindo cada vez mais resíduos sólidos, e neste, existe um potencial energético que não pode ser negligenciado. Neste contexto, a combustão se mostra uma boa alternativa para o reaproveitamento energético desses resíduos, no entanto, é indispensável um entendimento do processo, bem como das variáveis de operação. Portanto, este trabalho tem como objetivo apresentar uma modelagem para as equações de energia que governam a transferência de calor em um meio poroso reativo das fases sólida e gasosa e, ao mesmo tempo, simular o processo de combustão smouldering em meio poroso utilizando um software de simulação gratuito, o OpenFOAM, principal ferramenta utilizada neste trabalho. É apresentado para o leitor uma concisa descrição do pacote de simulação utilizado juntamente com suas principais características. Os resultados simulados são comparados com resultados experimentais obtidos pela célula de combustão instrumentada desenvolvida no Laboratório de Combustíveis e Combustão da Universidade Federal do Espírito Santo para estudos da combustão em meio poroso. Por último, apresenta-se a influência de parâmetros físicos, como espessura da frente, fração volumétrica de sólido e velocidade de resfriamento, na evolução da temperatura simulada no interior do leito.
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Monhol, Filipe Arthur Firmino. "Uma contribuição experimental aos fundamentos da propagação de uma frente de combustão em meio poroso." reponame:Repositório Institucional da UFES, 2015. http://repositorio.ufes.br/handle/10/1714.
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A propagação de uma frente de combustão ocorre numa variedade de situações e para diferentes propósitos industriais. O desempenho desses processos precisa melhorar e ao mesmo tempo reduzir os níveis de emissões para atender às normas de emissões internacionais. Para isso é necessário um certo grau de conhecimento tanto do processo como dos fenômenos da combustão. Em todos as situações envolvendo a combustão, a propagação é iniciada por uma fonte de calor e, após a ignição do combustível, a frente de combustão alcança o combustível adjacente. Estudos anteriores mostraram a ignição e propagação de uma frente de combustão como um fenômeno complexo que depende de processos químicos, térmicos e físicos. O presente trabalho abordou os desafios encontrados durante uma abordagem empírica para análise da propagação de uma frente de combustão em leito fixo. A partir da utilização de combustíveis simulados foram analisados: a influência da composição do combustível no comportamento da ignição do mesmo, as características da propagação da frente de combustão (regime de combustão, retração do leito e estrutura da frente) e a influência da ignição do combustível na propagação da frente de combustão. Foi possível realizar um mapeamento, para diferentes composições, do comportamento da ignição de combustíveis sólidos. A partir dos resultados de propagação da frente verificou-se que ocorrem basicamente três estágios de combustão no leito: ignição, propagação e oxidação do carbono fixo remanescente. Através das análises de gás notou-se a existência de dois regimes de combustão no leito: limitada pela reação e limitada pelo oxigênio. Foi obtido que em leitos com alta porcentagem de material inerte, onde há maior estabilidade, há uma maior influência da ignição na frente de combustão. Assim, mostrou-se como esses conhecimentos são úteis em diversas aplicações e processos industriais.
The combustion front propagation occurs in a variety of situations and for different industrial purposes. The performance of these processes needs to be improved and at the same time to reduce emission levels to meet the international standards. For this purpose, is needed a certain degree of knowledge of both processes of combustion phenomena. In all situations involving combustion phenomena, the propagation is initiated by a source of heat, and after fuel ignition, combustion front reaches the adjacent fuel. Previous studies have shown the ignition and the combustion front propagation as a complex phenomenon which depends on chemical, thermal and physical processes. This work focuses on the challenges encountered during an empirical approach to analyze the propagation of a combustion front in fixed bed. From the use of simulated fuels, it were analyzed: the influence of fuel composition on the behavior of its ignition, the characteristics of the combustion front propagation (combustion regime, shrinkage of the bed and the front structure) and the influence of fuel ignition in the propagation of the combustion front. It was possible to perform a mapping of ignition behavior of the solid fuel for different compositions. From the results of front propagation, it was found that, basically, three combustion stages occur in the bed: Ignition, Propagation and Oxidation of the remaining fixed carbon. Through gas analysis it was noted that there were two reaction modes present in the bed: reaction limited and oxygen limited. It was obtained than in bed with high content of inert materials, where there is greater stability, there is a greater influence from the ignition to the combustion front. Thus, it was shown how these skills are useful in various applications and industrial processes.
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Wang, Houzhi. "Initiation of smouldering combustion in biomass." Thesis, 2018. http://hdl.handle.net/2440/114254.
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Wildfires are naturally occurring phenomena that result in significant and catastrophic
damage. Due to climate change, there has been a significant increase in
the frequency, severity, and extent of wildfires. Therefore, there is a growing need
to mitigate wildfire risk. In order to help mitigate the risk of wildfires, greater
understanding is required. One particular gap in knowledge is the impact of smouldering
combustion of potential fuel on wildfires. This thesis focuses on combustion
of fuel beds in wildfires. Specifically, the thesis targets smouldering combustion.
Smouldering combustion is a common type of combustion regime in wildfires and
hazard reduction burning (a wildfire mitigation measure). Smouldering is a slow
and low-temperature form of combustion, which shows no
flame. Smouldering is a
serious hazard because of its low ignition temperature, which makes it particularly
relevant to fire initiation and spread. Smouldering plays a vital role in wildfires,
as many forest biomass fuels such as grass, leaves and coarse woody debris are
prone to smoulder. Most previous studies of smouldering combustion have only
been carried out on polyurethane foam, due to its importance for residential fires.
However, smouldering has been scarcely investigated from the point of view of
wildfires. For example, smouldering combustion of forest fuel is scarcely studied.
Hence, the project aims to develop a greater understanding of the initiation of
smouldering combustion in biomass under different conditions with an emphasis
on wildfire.
Locating smouldering combustion in wildfires and hazard reduction burning
is difficult and time-consuming, as there is no effective method to identify the
initiation of smouldering combustion in biomass fuel beds. It is critical to know when and where smouldering combustion in a biomass fuel bed starts, as smouldering
combustion could transition to
flaming combustion under certain conditions.
Radiation is one of the important heat transfer mechanisms in wildfires; however,
there are few studies on smouldering combustion in biomass fuel beds started by
external radiant heat
flux. Although oxidiser
flow rate and oxygen concentration
have significant in
influences on the propagation of smouldering front, their effects on
the initiation of smouldering combustion in biomass fuels are not well understood.
Hence, the effects of oxidiser
flow rate and oxygen concentration on the initiation
of smouldering combustion are investigated. Fuels in a forest are diverse, and it
is essential to have a better understanding of what effects forest fuels have on
smouldering combustion. Thus, the effects of plant species and plant parts on the
initiation of smouldering in biomass fuel beds are also investigated. Within this
framework, the work presented in this thesis can be split into two main topics:
1. Conditions required to initiate smouldering combustion in bio-
mass fuel beds
The required radiant heat
flux and air
flow rate for the initiation of smouldering
and
flaming combustion in a biomass fuel bed are investigated in an experimental
testing rig. This investigation identifies and quantifies smouldering and
flaming
combustion in a biomass fuel bed based on the measurements of temperature,
product gas concentration and mass change, and the required radiant heat
flux
and air
flow rate for the initiation of smouldering and
flaming combustion are
determined. The effects of heating time and oxygen concentration on the initiation
of radiation-aided and self-sustained smouldering combustion are investigated in
the same testing rig. In this experimental study, the differences between radiation-aided
and self-sustained smouldering combustion are characterised based on the
measurements of temperature, product gas concentration and mass change, and
the required heating time and oxygen concentration for radiation-aided and self-sustained
smouldering combustion are determined.
2. Factors that influence smouldering combustion in biomass fuel
beds
The results from the first topic reveal that oxygen availability has significant effects
on the initiation of smouldering combustion in a biomass fuel bed. The air
permeability of a biomass fuel bed determines oxygen availability in that fuel bed.
Hence, the air permeability of natural forest fuel beds is investigated in an air
permeability testing rig. In this study, the air permeability of natural forest fuel beds is determined using experimental and theoretical methods. A comparison
between the experimental and theoretical methods is made. The effects of Euca-
lyptus species and plant parts on smouldering combustion are also investigated.
In this study, the different plant parts from different Eucalyptus species are characterised
based on the results of the thermogravimetric and ultimate analyses.
The results of this study show that the differences among the different plant parts
from different Eucalyptus can be characterised and quantified based on the results
of the thermogravimetric and ultimate analyses. It is also found that Eucalyptus
species and plant parts have significant effects on smouldering combustion.
Although this thesis covers a series of experimental studies of the initiation
of smouldering combustion in biomass fuel beds. There are still many important
factors to be considered. For examples, the thesis focuses on small-scale laboratory
experiments to better understand the fundamental studies of smouldering combustion
of biomass. However, the real-world conditions could be much more complex.
For example, forest fuel beds are composed with fuel particles with various sizes
and shapes. These factors also have effects on smouldering combustion.Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, School of Mechanical Engineering, 2018
Book chapters on the topic "Smouldering combustion"
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Hakes, Raquel S. P., Hamish Allan, Da Ke, Sara S. McAllister, Matthew W. Kury, Sarah N. Scott, and Rory M. Hadden. "Experimental and numerical characterisation of the smouldering combustion of peat." In Advances in Forest Fire Research 2022, 1457–61. Imprensa da Universidade de Coimbra, 2022. http://dx.doi.org/10.14195/978-989-26-2298-9_222.
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Smouldering peat fires are a major source of greenhouse gas emissions. As the climate warms, the frequency and severity of peat fires will continue to increase, with a single large fire event contributing as much CO2 to the atmosphere per day as an industrialized country. Estimates of the amount of CO2 released by peat fires contain large uncertainties, driven by overwhelming uncertainty in the mass of peat consumed in these fires. The present work addresses uncertainties in peat fire dynamics and smouldering through an iterative experimental and modelling process. Presented here is a first step towards predicting greenhouse gas emissions. Experiments focus on capturing the mass burnt in a smouldering peat fire and describing the smouldering—pyrolysis and oxidation—process. Mass loss rate is found to vary as a sample is tested in lateral spread vs downward spread configurations. A one-dimensional model of peat smouldering is implemented, with initial qualitative results presented here, showing the drying of wet peat and the pyrolysis front. These results represent the current work in progress on this effort. Further work will compare experimental and simulation results for additional parameters of interest, and simulations will be used to inform which soil parameters to explore experimentally.
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"Spontaneous Ignition within Solids and Smouldering Combustion." In An Introduction to Fire Dynamics, 317–48. Chichester, UK: John Wiley & Sons, Ltd, 2011. http://dx.doi.org/10.1002/9781119975465.ch8.
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Yermán, Luis. "Self-sustaining Smouldering Combustion as a Waste Treatment Process." In Developments in Combustion Technology. InTech, 2016. http://dx.doi.org/10.5772/64451.
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Santoso, Muhammad A., Eirik Christensen, Hafiz M. F. Amin, Pither Palamba, Yuqi Hu, Dwi M. J. Purnomo, Wuquan Cui, et al. "GAMBUT field experiment of peatland wildfires in Sumatra: infrared measurements of smouldering spread rate." In Advances in Forest Fire Research 2022, 880–85. Imprensa da Universidade de Coimbra, 2022. http://dx.doi.org/10.14195/978-989-26-2298-9_133.
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Peatland wildfires present challenge to the mitigation of climate change due to the large amount of ancient carbon emission. Once ignited, the organic soils in peatland can burn for a long periods (weeks to months) and are difficult to extinguish. Peat fire is governed by smouldering combustion which is the slow, low temperature, flameless burning of charring porous fuel, and the most persistent type of combustion phenomena. The detection and monitoring of peatland wildfires are often conducted by remote sensing like satellite. However, there is currently a missing gap between spread of peat fires in the small laboratory scale and the large field scale. This work covers this gap by conducting field-scale controlled experiment of peatland wildfires. The experimental campaign, GAMBUT, was conducted in the peatland of Sumatra, Indonesia, covering an area of 374 m2. Smouldering spread rate was measured by infrared cameras and subsurface thermocouples. The smouldering sustained up to 10 days and nights, and survived against three rainfalls. Observation from infrared images show that horizontal smouldering spread rate fluctuates during propagation. However, no significant difference was found between average horizontal spread rates from the measurements of infrared camera and thermocouples, i.e. 0.3±0.13 cm/h to 0.8±0.2 cm/h. The spread rates here agree with the trend in the literature of laboratory experiments, fit within in the ranges of high moisture (MC) and inorganic (IC) contents of the soil (MC between 23 to 141% and IC between 49 to 72%). Even though slower, the fires thrived up to 10 days and against three rainfalls, demonstrating the persistency of smouldering peat fires and calling for a consideration of degraded peatland with high inorganic content to be consistently included in the mapping and monitoring of peatland area. GAMBUT presents a unique understanding of peatland wildfires at field conditions and aims to contribute to the better monitoring and mitigation acts.
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Christensen, Eirik G., Yuqi Hu, Muhammad A. Santoso, Wuquan Cui, and Guillermo Rein. "Arctic fires and smouldering combustion: influence of soil and air temperature on fire spread." In Advances in Forest Fire Research 2022, 844–48. Imprensa da Universidade de Coimbra, 2022. http://dx.doi.org/10.14195/978-989-26-2298-9_128.
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Peat fires smoulder for long periods (weeks to months) and releasing large amount of ancient carbon that have been stored for millennia in the organic soils. Recent wildfires in Arctic regions have burned unprecedented swaths of land, demonstrating a detrimental change in the arctic fire regime and highlighting the vulnerability of these biomes to climate change. This work aims to experimentally study Arctic peat fires in the lab scale by using an experimental rig with adjustable air temperature and bottom boundary of the peat fire which imitate the condition of permafrost in the Arctic. The initial temperature of the peat sample varied from -13 to 18°C, and the moisture content (MC) was varied from 50 to 120% in dry-mass basis. The experimental results show that smouldering can be sustained with soil temperatures below the freezing point of water. The range of condition temperature in this study was found to insignificantly affect spread rate but have profound effect on the depth of burn, increasing by up to 66% as bottom boundary decreased from 21 to -7°C. We found that the critical moisture content of ignition under cold condition in this work is between 110 and 120% (dry-mass basis), and is lower than the literature in room temperature (160%). At high moisture content (≥100% MC), smouldering was weakly spreading under air temperature of ~12°C, initial peat temperature of -11°C, and bottom boundary of -7°C. However, spread rate significantly increased as the air and bottom boundary temperatures were increased to 22°C, demonstrating overwintering fires which often found in the Arctic when peat fires were considered to be extinguished only to resurface when warmer season arrives. This study is the first experimental work on smouldering Arctic wildfires with findings that can improve our understanding on the effect of cold temperatures on the smouldering dynamics of peat fires, and presents a novel methodology to investigate Arctic fires at laboratory scale.
Conference papers on the topic "Smouldering combustion"
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Buckmaster, John. "Smouldering combustion." In 34th Aerospace Sciences Meeting and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1996. http://dx.doi.org/10.2514/6.1996-258.
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Zanoni, Marco A. B., Jason I. Gerhard, and Jose L. Torero. "Experimental Measurements of the Volumetric Heat Transfer Coefficient between Forced Air and Sand at Reynold’s Numbers Relevant to Smouldering Combustion." In International Conference of Fluid Flow, Heat and Mass Transfer. Avestia Publishing, 2016. http://dx.doi.org/10.11159/ffhmt16.150.
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