Glowing ignition of wood: the onset of surface combustion

Boonmee, Nathasak; Quintiere, James G.

doi:10.1016/j.proci.2004.07.022

Cited by 78 publications

(84 citation statements)

References 15 publications

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“…2b). This makes sense because pyrolysis is endothermic and requires an external supply of heat to continue, such that when exposed to a given heat flux, the temperature of non-ignited wood remains constant (Boonmee and Quintiere 2005). This also explains the positive correlation between reflectance and temperature in ovencreated chars.…”

Section: Resultsmentioning

confidence: 99%

The formation of charcoal reflectance and its potential use in post-fire assessments

Belcher

Hudspith

2016

Int. J. Wildland Fire

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Abstract. Charcoal has an exceptional ability to reflect light when viewed using reflectance microscopy. The amount of light reflected is variable depending on the differential ordering of graphite-like phases within the charcoal itself. It has been suggested that this relates to the temperature of formation, whereby higher formation temperatures result in high charcoal reflectance. However, this explanation is derived from oven-based chars that do not well represent the natural combustion process. Here, we have experimentally created charcoals using a cone calorimeter, in order to explore the development of charcoal reflectance during pre-ignition heating and peak heat-release rate, through to the end of flaming and the transition to char oxidation. We find that maximum charcoal reflectance is reached at the transition between pyrolysis and char oxidation, before its conversion to mineral ash, and indicates that our existing understanding of reflectance is in error. We suggest that charcoal reflectance warrants additional study as it may provide a useful quantitative addition to ground-based fire severity surveys, because it may allow exploration of surface heating after the main fire front has passed and the fire transitions to smouldering phases.

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Section: Resultsmentioning

confidence: 99%

The formation of charcoal reflectance and its potential use in post-fire assessments

Belcher

Hudspith

2016

Int. J. Wildland Fire

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“…Boonme and Quintiere [9] used the classical stagnant layer model (sometimes called the Stefan problem) to account for the effect of blowing through a Spalding mass transfer number (B number). Due to the relatively large number of species and reactions included in the modeling approach (four condensed phase species, seven gas phase species, four heterogeneous reactions, and two homogeneous reactions) almost 50 model input parameters (thermal properties, reaction coefficients, etc.)…”

Section: Discussionmentioning

confidence: 99%

“…23 and Eq. 24 differs from the conventional modeling approach wherein char oxidation is viewed as a heterogeneous process occurring at (or near) the surface of a decomposing solid [9,10]. In the present work, oxidative exothermic reactions, including both heterogeneous reactions (Eq.…”

Section: Modeling Approachmentioning

confidence: 99%

“…Although they simulated Cone Calorimeter experiments conducted in air, all three reactions were modeled as endothermic, so oxidative pyrolysis was not explicitly considered. Oxidative pyrolysis of wood has been simulated by including the effect of exothermic reactions in the exposed face boundary condition [9,10], but oxidative reactions do not necessarily occur only immediately at the exposed surface.…”

Section: Introductionmentioning

confidence: 99%

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A model for the oxidative pyrolysis of wood

Lautenberger

Fernandez-Pello

2009

Combustion and Flame

125

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“…Char oxidation is normally viewed as a heterogeneous process occurring near the surface of a decomposing solid. For example, Weng et al [208] and Boonme and Quintiere [210] 2.3). In reality, the chemical composition of "char" formed by thermal pyrolysis of wood is not expected to be the same as that formed by oxidation of the wood.…”

Section: Oxidative Pyrolysismentioning

confidence: 99%

Generalized pyrolysis model for combustible solids

Lautenberger

Fernandez-Pello

2009

Fire Safety Journal

307

259

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This dissertation presents the derivation, numerical implementation, and verification/validation of a generalized model that can be used to simulate the pyrolysis, gasification, and burning of a wide range of solid fuels encountered in fires. The model can be applied to noncharring and charring solids, composites, intumescent coatings, and smolder in porous media. Care is taken to make the model as general as possible, allowing the user to determine the appropriate level of complexity to include in a simulation. The model considers a user-specified number of gas phase and condensed phase species, each having its own temperature-dependent thermophysical properties.Any number of heterogeneous (gas-solid) or homogeneous (solid-solid or gas-gas) reactions can be specified. Both in-depth radiation transfer through semi-transparent media and radiation transport across pores are considered. Volume change (surface regression or swelling/intumescence) is handled by allowing the size of grid points to change as dictated by mass conservation. All volatiles generated inside the solid escape to the ambient with no resistance to mass transfer unless a pressure solver is invoked; the resultant flow of volatiles is then calculated according to Darcy's law. A gas phase 2 convective-diffusive solver can be invoked to determine the composition of the volatiles.Oxidative pyrolysis is simulated by modeling diffusion of oxygen from the ambient into the pyrolyzing solid where it may participate in reactions. Consequently, the mass flux and composition of volatiles escaping from the solid can be calculated. To aid in determining the required input parameters, the model is coupled to a genetic algorithm that can be used to estimate the required input parameters from bench-scale fire tests or thermogravimetric analysis.

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Glowing ignition of wood: the onset of surface combustion

Cited by 78 publications

References 15 publications

The formation of charcoal reflectance and its potential use in post-fire assessments

The formation of charcoal reflectance and its potential use in post-fire assessments

A model for the oxidative pyrolysis of wood

Generalized pyrolysis model for combustible solids

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