Modeling pyrolysis of wet wood under external heat flux

Shen, Dekui; Fang, M. X.; Luo, Zhongyang; Cen, Ke Fa

doi:10.1016/j.firesaf.2006.09.001

Cited by 79 publications

(77 citation statements)

References 27 publications

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“…This is presumably because model calculations (and experimental data) were truncated at surface temperatures below 400 ºC, so oxidative reactions had very little influence. Shen et al [211] obtained good agreement between measured and calculated temperatures (at the surface and in depth), but did not present a comparison of modeled and measured mass loss rates. Weng et al [208] recently modeled the same set of experiments [84] that are modeled here.…”

Section: Oxidative Pyrolysismentioning

confidence: 97%

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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: Oxidative Pyrolysismentioning

confidence: 97%

“…Shen et al [211] recently modeled the pyrolysis of several different species of wet wood using 3 parallel reactions. Although they simulated cone calorimeter experiments conducted in air, all three reactions were modeled as endothermic.…”

Section: Oxidative Pyrolysismentioning

confidence: 99%

Generalized pyrolysis model for combustible solids

Lautenberger

Fernandez-Pello

2009

Fire Safety Journal

303

259

View full text Add to dashboard Cite

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“…At present, many simplified reaction mechanisms exist for the study of biomass pyrolysis. These are either one-step global models (15)(16)(17)(18)(19) or one-or two-stage multiple reaction models (20,(21)(22)(23)(24)(25)(26) . Di Blasi (27) and Prakash and Karunanithi (28) have given some comprehensive reviews of advances in modeling and simulation of chemical and physical processes of wood and biomass pyrolysis.…”

Section: Introductionmentioning

confidence: 99%

Numerical and Experimental Investigation of Intra-Particle Heat Transfer and Tar Decomposition during Pyrolysis of Wood Biomass

Okekunle

Pattanotai

Watanabe

et al. 2011

JTST

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Pyrolysis of cylindrical woody biomass has been investigated both numerically and experimentally with emphasis on intra-particle heat transfer and tar decompostion. In experiment, wood cylinder of 8 mm diameter and 9 mm length was pyrolyzed in an infrared reactor exposed to both convective and radiative heat fluxes in argon environment. The final reactor temperature was 973 K, and heating rate was 5, 10 and 30 K/s. Three K-type thermocouples were located in the sample to measure intra-particle temperature history. The weight fraction history and intra-particle temperature profiles were measured at different runs. Tar was obtained at a cold trap. In calculation, a two-dimensional, unsteady state single particle model was developed and used to simulate the pyrolysis process. Wood cylinder was modeled as an isotropic porous solid. Solid mass conservation equations were solved by using first-order Euler Implicit Method. Gas phase mass conservation equations and energy conservation equation were discretised by finite volume method. In order to investigate the effect of intra-particle heat transfer, simulations were carried out, first, by considering temperature gradient and second, by assuming uniform temperature within the sample. When temperature gradient was considered, simulation results were in good agreement with experimental data. When uniform intra-particle temperature was used in the simulation, simulation results were quite different from experimental measurements, the degree of difference increasing with increase in heating rate. Both calculation and experiment showed tar yield decreased with increasing heating rate. This was because tar formation reaction and intra-particle tar decomposition reactions were enhanced by increase in heating rate but the latter was dominant. It was shown that intra-particle heat transfer and tar decomposition played an important role in pyrolysis characteristics of wood cylinder.

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“…Shen et al [8] modeled the pyrolysis of several different species of wet wood using three parallel reactions. Although they simulated Cone Calorimeter experiments conducted in air, all three reactions were modeled as endothermic, so oxidative pyrolysis was not explicitly considered.…”

Section: Introductionmentioning

confidence: 99%