Predicting the pyrolysis of wood considering char oxidation under different ambient oxygen concentrations

Weng, W.G.; Hasemi, Y.; Fan, Weicheng

doi:10.1016/j.combustflame.2005.12.016

Cited by 35 publications

(33 citation statements)

References 11 publications

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“…Reference [84] The experiments of Kashiwagi, Ohlemiller, and Werner [84] have been simulated by Jia et al [60] and Weng et al [208] using integral charring models. Jia et al [60] modeled only the experiments [84] that were conducted in pure nitrogen because their model did not include exothermic char oxidation.…”

Section: Charring Gasification -White Pinementioning

confidence: 99%

“…Jia et al [60] modeled only the experiments [84] that were conducted in pure nitrogen because their model did not include exothermic char oxidation. Weng et al [208] recently modeled the experiments [84] with a previously-developed integral model that was modified to explicitly consider char oxidation. Both groups obtained reasonably good agreement between their model calculations and the experimental data.…”

Section: Charring Gasification -White Pinementioning

confidence: 99%

“…Here, the experiments are simulated in greater detail than in the earlier papers [60,208]. Model parameters are estimated from experimental data in a two-step process.…”

Section: Charring Gasification -White Pinementioning

confidence: 99%

“…In this work, temperature-dependent specific heat capacity and thermal conductivities are used for each condensed phase species. Although Jia et al [60] and Weng et al [208] simulated the same experiments, they used constant thermal properties.…”

Section: Thermal Pyrolysis Under Nitrogenmentioning

confidence: 99%

“…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%

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Generalized pyrolysis model for combustible solids

Lautenberger

Fernandez-Pello

2009

Fire Safety Journal

293

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: Charring Gasification -White Pinementioning

confidence: 99%

Section: Charring Gasification -White Pinementioning

confidence: 99%

“…Here, the experiments are simulated in greater detail than in the earlier papers [60,208]. Model parameters are estimated from experimental data in a two-step process.…”

Section: Charring Gasification -White Pinementioning

confidence: 99%

Section: Thermal Pyrolysis Under Nitrogenmentioning

confidence: 99%

Section: Oxidative Pyrolysismentioning

confidence: 99%

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Generalized pyrolysis model for combustible solids

Lautenberger

Fernandez-Pello

2009

Fire Safety Journal

293

259

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Modelling of a downdraft biomass gasifier with finite rate kinetics in the reduction zone

Roy

Datta

Chakraborty

2009

Int. J. Energy Res.

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SUMMARYA model of a downdraft gasifier has been developed based on chemical equilibrium in the pyro-oxidation zone and finite rate kinetic-controlled chemical reactions in the reduction zone. The char reactivity factor (C RF ) in the reduction zone, representing the number of active sites on the char and its degree of burn out, has been optimized by comparing the model predictions against the experimental results from the literature. The model predictions agree well with the temperature distribution and exit gas composition obtained from the experiments at C RF 5 100. A detailed parametric study has been performed at different equivalence ratios (between 2 and 3.4) and moisture content (in the range of 0-40%) in the fuel to obtain the composition of the producer gas as well as its heating value. It is observed that the heating value of the producer gas increases with the increase in the equivalence ratio and decrease in the biomass moisture content. The effect of divergence angle of the reduction zone geometry (in the range of 30-1501) on the temperature and species concentration distributions in the gasifier has been studied. An optimum divergence angle, giving the best quality of the producer gas, has been identified for a particular height of the reduction zone.

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Experimental investigation on the effect of ambient pressure on thermal runaway and fire behaviors of lithium‐ion batteries

et al. 2019

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Summary To investigate the impacts of ambient pressure on thermal runaway and fire behaviors of lithium‐ion battery (LIB), experimental measurement and theoretical analysis with serial conditions are conducted at two altitudes. The well‐designed experimental equipment and operating conditions have enabled the accurate evaluation of ambient pressure effects. Results show that the first abrupt temperature change in Hefei (ambient pressure 100.8 kPa) is higher than that in Lhasa (64.3 kPa). The difference in ambient pressure at two altitudes leads to different relief valve crack temperature and time. The average burning rate in Hefei is larger than that in Lhasa, and the estimated pressure effect factor is quite different for detailed pack conditions and varies within the range of 0.083‐1.39. The ambient pressure has a greater effect on the heat release rate and total heat release than the mass loss, and the effective combustion heat under the low pressure is lower than that in normal condition. This work can provide more comprehensive and useful data for the safety management of LIBs at low pressure environments.

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Predicting the pyrolysis of wood considering char oxidation under different ambient oxygen concentrations

Cited by 35 publications

References 11 publications

Generalized pyrolysis model for combustible solids

Generalized pyrolysis model for combustible solids

Modelling of a downdraft biomass gasifier with finite rate kinetics in the reduction zone

Experimental investigation on the effect of ambient pressure on thermal runaway and fire behaviors of lithium‐ion batteries

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