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Author (up) Correa, N.; Cuevas, J.; Fuentes, A.; Torero, J.L.; Reszka, P.
Title Understanding the effect of char oxidation on wood temperature profiles for varying heating and oxygen conditions Type
Year 2024 Publication Fire Safety Journal Abbreviated Journal Fire Saf. J.
Volume 142 Issue Pages 104049
Keywords Pyrolysis modeling; Wood heating; Temperature profile; Structural fire behavior
Abstract The use of mass timber framing as a sustainable material, particularly in high-rise buildings, requires detailed structural fire performance calculations. Thermal models describing only the solid phase are cost-effective alternatives to provide information to structural behavior models. Their accuracy depends on an adequate description of drying, pyrolysis, charring and eventually flaming phenomena. While in recent years there have been considerable contributions to the development of such models, there are still open questions. This work proposes a thermal model which incorporates char oxidation, describing both the kinetic-and diffusion controlled regimes. The model was used to replicate two sets of experimental results which used standard fire calorimeters to study the ignition of thick wood specimens within a range of incident heat fluxes and oxygen concentrations, respectively. The model yields adequate temperature predictions in the early heating stages, but fails to replicate the behavior at later stages, when the effect of the surface combustion is noticeable. In terms of mass loss rates, a poorer performance is observed. To change from one oxidation regime to another, a Damkohler number is proposed, based on char oxidation reaction rates. It is found that for compartment fire conditions, char oxidation will mostly occur develop under diffusion-controlled conditions.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0379-7112 ISBN Medium
Area Expedition Conference
Notes WOS:001112512500001 Approved
Call Number UAI @ alexi.delcanto @ Serial 1917
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Author (up) Parot, R.; Rivera, J.I.; Reszka, P.; Torero, J.L.; Fuentes, A.
Title A simplified analytical model for radiation dominated ignition of solid fuels exposed to multiple non-steady heat fluxes Type
Year 2022 Publication Combustion and Flame Abbreviated Journal Combust. Flame
Volume 237 Issue Pages 111866
Keywords Ignition delay time; Fire safety; Integral heat equation; Solid ignition; Translucent solids; In-depth absorption of radiation
Abstract Heat fluxes from fires are strongly time-dependent. Historically, the thermal ignition theory in its classical form has neglected this time dependency until recent years, where theories have been developed to include time-varying incident heat fluxes. This article proposes a simplified general model formulation for the heating of solid fuels exposed to four different heat flux behaviors, considering the penetration of radiation into the medium. The incident heat flux cases developed where: Constant, Linear, Exponential and Polynomial, which represent different situations related to structural and wildland fires. The analytical models consider a spatially averaged medium temperature and exact and approximate solutions are presented, based on the critical ignition temperature criterion, which are valid for solids of any optical thickness. The results were validated by comparison with various models presented in the literature, where the model granted in this work was capable to adjust to all of them, especially when high heat fluxes are involved. Therefore, the proposed model acquires a significant engineering utility since it provides a single model to be used as a general and versatile tool to predict the ignition delay time in a manageable way for solid fuels exposed to different fire conditions.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0010-2180 ISBN Medium
Area Expedition Conference
Notes WOS:000735880500007 Approved
Call Number UAI @ alexi.delcanto @ Serial 1521
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