Modelling thermal degradation of polymers using single-step first-order kinetics

Staggs, J.E.J.

doi:10.1016/s0379-7112(98)00026-5

Cited by 55 publications

(35 citation statements)

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“…Pyrolysate generation has been treated as occurring only at the surface [3,40] or more frequently, as a distributed in-depth reaction [41][42][43][44][45][46][47][48][49][50][51] to account for sub-surface fuel generation. With ablation models [35][36][37][38][39] or finite-rate kinetics models that relate the fuel generation rate to the surface temperature [3,40], all fuel generation occurs at the surface.…”

Section: Comprehensive Pyrolysis Models: Thermoplasticsmentioning

confidence: 99%

Generalized pyrolysis model for combustible solids

Lautenberger

Fernandez-Pello

2009

Fire Safety Journal

303

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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Section: Comprehensive Pyrolysis Models: Thermoplasticsmentioning

confidence: 99%

Generalized pyrolysis model for combustible solids

Lautenberger

Fernandez-Pello

2009

Fire Safety Journal

303

259

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“…If the external heat flux is q    at the exposed surface, T is temperature and  is thermal conductivity then ignoring in-depth absorption, the characteristic thermal penetration depth assuming conduction heat transfer is q T     /   , where T  is a physically significant temperature interval. For ignition it is sensible to take T  as the characteristic kinetic temperature range [6], which corresponds approximately to the temperature range over which the material pyrolyses at constant heating rate. Thus it seems reasonable that in-depth absorption In-depth absorption of radiation in the condensed phase is only part of the problem, however.…”

Section: Introductionmentioning

confidence: 99%

The effects of gas-phase and in-depth radiation absorption on ignition and steady burning rate of PMMA

Staggs

2014

Combustion and Flame

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Article:Staggs, J (2014) The effects of gas-phase and in-depth radiation absorption on ignition and steady burning rate of PMMA. Combustion and Flame, 161 (12 ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request.

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“…With the help of energy conservation, the portion of solid in the grid can be calculated, which leads to the prediction of the position of the solid-liquid interface. 9 To compare the analytical and numerical solutions, the data in Voller [18], listed below, are used. λ is found to be equal to 0.2037 for this particular setting [14].…”

Section: Verification Of the Methodsmentioning

confidence: 99%

“…It has also been investigated numerically [8][9][10][11]. Melting, and its effect on pyrolysis, however, has been given much less attention, although there is evidence that melting may play an important role in the combustion of polymers [12,13], and thus there is need for further understanding of the combined effect of pyrolysis and melting on the combustion of polymeric materials.…”

Section: Introductionmentioning

confidence: 99%

An enthalpy-temperature hybrid method for solving phase-change problems and its application to polymer pyrolysis and ignition

Zhou

Fernandez‐Pello

2000

Combustion Theory and Modelling

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In this work, an enthalpy-temperature hybrid method is proposed for the numerical solution of generalized phase change problems, and applied to the prediction of polymer pyrolysis and ignition. The basic idea of this method is to treat both enthalpy and temperature as independent variables, and to solve the conservation equations and the constitutive equations (enthalpy-temperature relations) simultaneously. The formula of the enthalpy-temperature relations are not necessary the same for different phases, but can be chosen independently according to the characteristics of physical problems and the convenience of numerical analysis for each respective phase. Therefore this method applies to the problems regardless of the form of the constitutive equations. It overcomes the difficulty or even impossibility encountered in the traditional enthalpy-temperature method, of which either enthalpy or temperature must be consistently and explicitly expressed as a function of the other over all the phases. The method is first applied to a one-dimensional classical freezing problem for method demonstration and verification. It is found that the numerical results of temperature history and the position of phase change interface agree well with the analytic solution existing in the literature. The method is then applied to the numerical simulation of the pyrolysis and ignition of a composite material with a polymer as the matrix and fiberglass as the filling material. Three models of oxygen distribution in the molten layer are considered to explore the melting and oxygen effects on the polymer pyrolysis. Numerical calculation shows that high oxygen concentrations in the molten layer enhance the pyrolysis reaction, resulting in a larger amount of pyrolysate, but in lower surface temperatures of the sample. It also shows that distribution of oxygen in the molten layer has a strong effect on pyrolysate rate, and therefore on ignition and combustion of polymers. Comparison with available experimental data indicates that a model of oxygen distribution in the molten layer that is limited to a thin layer near the s urface describes best the ignition process for a homogeneously blended polypropylene/fiberglass composite.1

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Modelling thermal degradation of polymers using single-step first-order kinetics

Cited by 55 publications

References 0 publications

Generalized pyrolysis model for combustible solids

Generalized pyrolysis model for combustible solids

The effects of gas-phase and in-depth radiation absorption on ignition and steady burning rate of PMMA

An enthalpy-temperature hybrid method for solving phase-change problems and its application to polymer pyrolysis and ignition

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