Numerical examination of two-dimensional smolder structure in polyurethane foam

Dodd, Amanda B.; Lautenberger, Chris; Fernandez‐Pello, A. C.

doi:10.1016/j.proci.2008.06.196

Cited by 27 publications

(12 citation statements)

References 27 publications

(18 reference statements)

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“…A fellow graduate student has used it to simulate 2D smolder in polyurethane foam with a seven-step reaction mechanism [9]. With the exception of condensed phase advection, the model includes most physics and chemistry…”

Section: Model Capabilities and Potential Applicationsmentioning

confidence: 99%

“…The concept of a 4 critical mass loss rate at ignition was explored theoretically [7], and a theory was developed to explain the experimentally-observed increase in surface temperature at piloted ignition with applied heat flux [8]. The 1D numerical pyrolysis model described in this dissertation has recently been extended to two dimensions and used to simulate two-dimensional smolder structure with complex kinetics [9]. However, to focus the scope of this dissertation and limit its length, none of this work is discussed here; only 1D standalone numerical pyrolysis modeling and a related parameter estimation methodology are presented.…”

Section: Introductionmentioning

confidence: 99%

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Generalized pyrolysis model for combustible solids

Lautenberger

Fernandez-Pello

2009

Fire Safety Journal

302

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: Model Capabilities and Potential Applicationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Generalized pyrolysis model for combustible solids

Lautenberger

Fernandez-Pello

2009

Fire Safety Journal

302

259

View full text Add to dashboard Cite

show abstract

“…The solid density and heat capacity are defined as follows (Lautenberger et al, 2009;Dodd et al, 2009):…”

Section: B Heat and Mass Transfer Coefficientsmentioning

confidence: 99%

“…The kinetics parameters (pre-exponential factors, activation energies, reaction orders, and stoichiometry coefficients) are summarized in Table 2 (Ghabi et al, 2007 a, b;Dodd et al, 2009).…”

Section: Kinetic Modelmentioning

confidence: 99%

Computational Model of Smoldering Combustion in Polyurethane Foam

2019

JAFM

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Smoldering phenomenon can be described as a slow, low-temperature, flameless form of combustion, sustained by heterogeneous reactions with oxygen occurring at the surface of a condensed-phase fuel. In this work a computational study on the smoldering ignition and propagation in polyurethane foam is carried out. First, we investigated numerically the heat transfer and the fluid flow in porous media using the generalized lattice Boltzmann method (LBM). Our appropriate code is validated through the study of a thermal injected flow. LBM results are compared to analytical solutions and numerical results obtained using the Finite Difference Method. Second, the numerical model is extended to account for chemical reactions. We introduce the two-dimensional, transient, governing equations for smoldering combustion in a porous fuel. The model describes opposed and forward propagation according to appropriate assumptions. The kinetics model is based on a three-step mechanism. The temperature and char mass fraction profiles are studied at different cross-sections. Obtained results are compared to literature solutions. At the beginning, the important quantity of char is produced near the ignited boundary. To follow the phenomenon, the isotherms are presented at different instants. The results reproduce the features of the smoldering process and represent a significant step forward in smoldering combustion modeling.

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“…One study extended such studies to two-dimensions using a 7-step reaction scheme [21]. All of these models only considered the smoldering behavior under forced airflow or under microgravity where the effects of buoyant airflow could be ignored.…”

Section: Introductionmentioning

confidence: 99%

Smoldering propensity in upholstered furniture:

Yang¹,

Rein²,

Chen³

et al. 2020

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Reduced-scale mock-ups had been developed to assess and regulate smoldering ignition resistance of residential upholstered furniture (RUF). However, there are limited data available on the effect of the mock-up test configuration on smoldering propensity and how it affects the degree of correlation with full-scale performance. In this work, the smoldering propensity for standard mock-ups (SMs, where the foam is in contact with a support frame) and modified mock-ups (MMs, where an air gap is introduced between the foam and the frame), were computationally simulated and compared to experimental results. Experimental data showed an up to a four-fold increase in smoldering mass loss in a MM as compared to a SM for a test time of 35 min with a 51 mm-thick foam. The model results indicated that the buoyant airflow at the bottom of the mock-up was enhanced in the MM, giving rise to a higher foam oxidation rate, a higher peak smoldering temperature and higher mass loss rate as compared to the SM, and; that oxygen supply was dominated by diffusion-driven transport from the boundaries in proximity of the heating source in the SM. Additionally, the effects of foam thickness on smoldering propensity were studied experimentally and numerically with foam thicknesses of 51 mm (2 inch) and 76 mm (3 inch). With an increase in the foam thickness, the smoldering propensity is weakened in the MM but enhanced in the SM. The model was able to predict the ranking of smoldering propensity quantified by the mass loss in experiments: ML(t)SM2 < ML(t)SM3 < ML(t)MM3 < ML(t)MM2, where MLSM2 is the mass loss (ML) with a 51 mm-thick foam in SM, MLSM3 is the ML with a 76 mm-thick foam in SM, MLMM3 is the ML with a 76 mm-thick foam in MM and MLMM2 is the ML with a 51 mm-thick foam in MM. These results indicate that reduced-scale tests based on SM2 tends to underpredict smoldering propensity and that MM2 may offer a near-worst-case scenario, useful to identify the This publication is available free of charge from: https://doi.org/10.6028/NIST.TN.2087 upholstery materials that prevent most smoldering ignitions independent of the construction and geometry of the actual furniture.

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Numerical examination of two-dimensional smolder structure in polyurethane foam

Cited by 27 publications

References 27 publications

Generalized pyrolysis model for combustible solids

Generalized pyrolysis model for combustible solids

Computational Model of Smoldering Combustion in Polyurethane Foam

Smoldering propensity in upholstered furniture:

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