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Author Hernandez, N.; Fuentes, A.; Reszka, P.; Fernandez-Pello, A.C. doi  openurl
  Title Piloted ignition delay times on optically thin PMMA cylinders Type
  Year 2019 Publication Proceedings Of The Combustion Institute Abbreviated Journal Proc. Combust. Inst.  
  Volume 37 Issue 3 Pages 3993-4000  
  Keywords Integral heat equation; P-1 radiation model; Analytical model; Critical heat flux; Optically thin solids  
  Abstract The theory to predict ignition of solid fuels exposed to incident radiant heat fluxes has permitted to obtain simple correlations of the ignition delay time with the incident heat flux which are useful in practical engineering applications. However, the theory was developed under the assumption that radiation does not penetrate into the solid phase. In the case of semi-transparent solids, where the penetration of radiation plays an important role in the heating and subsequent ignition of the fuel, the predictions of the classical ignition theory are not applicable. A new theory for the piloted ignition of optically thin cylindrical fuels has been developed. The theory uses an integral method and an approximation of the radiative transfer equation within the solid to predict the heating of an inert solid. An exact and an approximate analytical solution are obtained. The predictions are compared with piloted ignition experiments of clear PMMA cylinders. The results indicate that for opticallythin media, the heating and ignition are not sensible to the thermal conductivity of the solid, they are highly dependent on the in-depth absorption coefficient. Using the approximate solution, the correlation 1/t(ig) proportional to (q)over dot(inc)'' was established. This correlation is adequate for engineering applications, and allows the estimation of effective properties of the solid fuel. The form of the correlation that was obtained is due to the integral method used in the solution of the heat equation, and does not imply that the semi-transparent solid behaves like a thermally thin material. The approximate solution presented in this article constitutes a useful tool for pencil-and-paper calculations and is an advancement in the understanding of solid-phase ignition processes. (C) 2018 The Combustion Institute. Published by Elsevier Inc. All rights reserved.  
  Address [Hernandez, N.; Fuentes, A.] Univ Tecn Feder Santa Maria, Dept Ind, Valparaiso, Chile, Email: pedro.reszka@uai.cl  
  Corporate Author Thesis  
  Publisher Elsevier Science Inc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1540-7489 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000456628600154 Approved  
  Call Number UAI @ eduardo.moreno @ Serial 973  
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Author Parot, R.; Rivera, J.I.; Reszka, P.; Torero, J.L.; Fuentes, A. doi  openurl
  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.  
  Address  
  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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