toggle visibility Search & Display Options

Select All    Deselect All
 |   | 
Details
   print
  Records Links
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  
Permanent link to this record
 

 
Author Reszka, P.; Cruz, J.J.; Valdivia, J.; Gonzalez, F.; Rivera, J.; Carvajal, C.; Fuentes, A. doi  openurl
  Title Ignition delay times of live and dead pinus radiata needles Type
  Year 2020 Publication Fire Safety Journal Abbreviated Journal Fire Saf. J.  
  Volume 112 Issue Pages 7 pp  
  Keywords Leaf senescence; Photosynthetic pigments; Critical heat flux; Moisture content; Wildland fire  
  Abstract There are still many open questions related to the fire behavior of live and dead wildland fuels and their senescence process. We have physically and biochemically studied live and dead pinus radiata needles, their aging process, and their fire behavior using a systematic aging procedure which allows to characterize the evolution of the fuel moisture content and the photosynthetic pigments over time, and to determine the period of time after sample collection in which specimens can be considered to be alive. Results show that pine needles stay alive for up to 12 h after collection if they remain attached to the twigs. The influence of senescence on spontaneous ignition was tested on two bench-scale devices, the I-FIT and the SCALA, under discontinuous and continuous configurations, respectively. Live pine needles showed larger critical heat fluxes than dead needles, while dead and re-hydrated samples have increased critical heat fluxes for greater moisture contents. Experimental results were interpreted with thermal models based on a two-phase description of the fuel layer. We established a correlation of the form 1/t(ig)proportional to q(inc)" for both ignition configurations, which is adequate for engineering applications and allows the estimation of effective properties for wildland fuel beds.  
  Address [Reszka, P.; Valdivia, J.] Univ Adolfo Ibanez, Fac Engn & Sci, Santiago, Chile, Email: andres.fuentes@usm.cl  
  Corporate Author Thesis  
  Publisher Elsevier Sci Ltd Place of Publication Editor  
  Language English 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:000527282900005 Approved  
  Call Number UAI @ eduardo.moreno @ Serial 1146  
Permanent link to this record
 

 
Author Rivera, J.I.; Ebensperger, F.; Valenzuela, F.; Escandar, L.; Reszka, P.; Fuentes, A. doi  openurl
  Title Understanding the role of fire retardants on the discontinuous ignition of wildland fuels Type
  Year 2023 Publication Proceedings Of The Combustion Institute Abbreviated Journal Proc. Combust. Inst.  
  Volume 39 Issue 3 Pages 3775-3783  
  Keywords Ignition delay time; Critical heat flux; Thermal model; Effective properties; Pine needles  
  Abstract This work reports on a theoretical and experimental study on the role of fire retardant treatments on the discontinuous ignition of wildland fuels. The effect of the concentration of fire retardant in the solution applied to the vegetation is as expected to increase the ignition delay time. We found that the fire retardant modifies the fuel bed effective thermophysical properties, delaying the thermal response of the specimen when subjected to an incident heat flux. Nevertheless, the critical heat flux remains unaltered within the experimental error. We followed a proven approach based on the thermal ignition theory and testing which however has not been previously employed to study fire retardants on wildland fuels. To carry this out, we performed experiments on the I-FIT apparatus, which yields repeatable results and controlled boundary conditions. The theoretical model shows a good agreement with the experimental results, delivering simple expressions for pencil-and-paper calculations of the ignition delay time and analytical tools to evaluate effective fuel properties. These results will help CONAF and other forest services around the world to gain insight on the optimal concentrations and delivery methods for these types of products during wildfire response. & COPY; 2022 The Combustion Institute. Published by Elsevier Inc. All rights reserved.  
  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 1540-7489 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:001019726900001 Approved  
  Call Number UAI @ alexi.delcanto @ Serial 1842  
Permanent link to this record
Select All    Deselect All
 |   | 
Details
   print

Save Citations:
Export Records: