A flame spread simulation based on a comprehensive solid pyrolysis model coupled with a detailed empirical flame structure representation (original) (raw)
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Proceedings of the Combustion Institute, 2013
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A mathematical model, FiresCone, was developed to simulate pyrolysis and combustion processes of combustible materials considering both gas and solid phases. FiresCone has been validated by experimental results of four types of combustible materials in a cone calorimeter, including wood, non-charring, charring and intumescent polymers. It was known that modeling results of mass loss rate fitted reasonably well with experiments under various heat fluxes. Both experiments and modeling results showed that peak mass loss rate of wood, non-charring and charring polymers happened near the end of burning, but for intumescent polymers they showed at the beginning because of expanded protective char layer. It was also known from modeling results that non-charring polymer were different from other three types of materials because of the characteristics of in-depth radiation and no burning residue. FiresCone intends to provide a practical tool for the investigation of fire behaviors of different types of combustible materials. It can expand the application fields of modeling as fire processes of different types of combustible materials under complicated environmental conditions have been considered.
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This study provides a thorough examination of whether a numerical pyrolysis model, which describes transient energy transport and chemical reactions taking place in a one-dimensional object, can be used as a practical tool for prediction and/or extrapolation of the results of fire calorimetry tests. The focus is on non-charring polymers, in particular-poly(methylmethacrylate), high-impact polystyrene, and highdensity polyethylene. First, relevant properties of these materials were measured and/or obtained from the literature. Subsequently, the values of these properties were used to simulate gasification and cone calorimetry experiments, which were performed under a broad range of conditions. A comparison with the experimental results indicates that the model gives reasonably good predictions of the mass loss and heat release histories. It also predicts the evolution of temperature inside the material samples.
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An enthalpy-based pyrolysis model for charring and non-charring materials in case of fire
Combustion and Flame, 2010
In a simulation of a developing fire, flame spread must be properly accounted for. The pyrolysis model is important in this respect. To that purpose, we develop a simplified enthalpy based pyrolysis model that is extendable to multi-dimensional solid-phase treatments. This model is to be coupled to gas phase turbulent combustion simulations. The description of the pyrolysis process is simplified in order to acquire short simulation times. In this paper, first, the basic thermodynamic description of pyrolysis phenomena is revisited for charring and non-charring materials, possibly containing moisture. The heat of pyrolysis is defined and its relation to the formation enthalpies of individual constituents is explained.
Journal of Combustion, 2011
Two solid pyrolysis models are employed in a concurrent-flow flame spread model to compare the flame structure and spreading characteristics. The first is a zeroth-order surface pyrolysis, and the second is a first-order in-depth pyrolysis. Comparisons are made for samples when the spread rate reaches a steady value and the flame reaches a constant length. The computed results show (1) the mass burning rate distributions at the solid surface are qualitatively different near the flame (pyrolysis base region), (2) the first-order pyrolysis model shows that the propagating flame leaves unburnt solid fuel, and (3) the flame length and spread rate dependence on sample thickness are different for the two cases.
Two‐dimensional model of burning for pyrolyzable solids
Fire and Materials, 2013
ABSTRACTQuantitative understanding of the processes that take place inside a burning material is critical for the prediction of ignition and growth of fires. To improve this understanding and enable predictive modeling, we developed a numerical pyrolysis solver called ThermaKin. This solver computes transient rate of gaseous fuel production from fundamental physical and chemical properties of constituents of a pyrolyzing solid. It was successfully applied to the simulation of combustion of a broad range of materials. One limitation of ThermaKin was that it could handle only one‐dimensional burning problems. As a consequence, flame spread, which is an important contributor to fire growth, could not be simulated. Here, we present a new computational tool, ThermaKin2D, that expands ThermaKin model to two dimensions and combines it with a flexible analytical representation of a surface flame. It is our expectation that this tool will enable highly accurate simulations of flame spread dy...