Valérie Cancellieri - Academia.edu (original) (raw)

Papers by Valérie Cancellieri

Fire

A safe separation distance (SSD) needs to be considered during firefighting activities (fire supp... more A safe separation distance (SSD) needs to be considered during firefighting activities (fire suppression or people evacuation) against wildfires. The SSD is of critical interest for both humans and assets located in the wildland–urban interfaces (WUI). In most cases, the safety zone models and guidelines assume a flat terrain and only radiant heating. Nevertheless, injuries or damage do not result exclusively from radiant heating. Indeed, convection must be also considered as a significant contribution of heat transfer, particularly in the presence of the combined effects of sloping terrain and a high wind velocity. In this work, a critical case study is considered for the village of Sari-Solenzara in Corsica (France). This site location was selected by the operational staff since high-intensity fire spread is likely to occur in the WUI during wind-blown conditions. This study was carried out for 4 m high shrubland, a sloping terrain of 12° and a wind speed of 16.6 m/s. The numerica...

Atmosphere

This paper reports two experimental fires conducted at field-scale in Corsica, across a particula... more This paper reports two experimental fires conducted at field-scale in Corsica, across a particular mountain shrubland. The orientation of the experimental plots was chosen in such a way that the wind was aligned along the main slope direction in order to obtain a high intensity fire. The first objective was to study the high intensity fire behavior by evaluating the propagation conditions related to its speed and intensity, as well as the geometry of the fire front and its impact on different targets. Therefore, an experimental protocol was designed to determine the properties of the fire spread using UAV cameras and its impact using heat flux gauges. Another objective was to study these experiments numerically using a fully physical fire model, namely FireStar3D. Numerical results concerning the fire dynamics, particularly the ROS, were also compared to other predictions of the FireStar2D model. The comparison with experimental measurements showed the robustness of the 3D approach ...

HAL (Le Centre pour la Communication Scientifique Directe), May 23, 2022

Imprensa da Universidade de Coimbra eBooks, 2022

This article presents a first attempt of implementation of a lab-scale methodology proposed to de... more This article presents a first attempt of implementation of a lab-scale methodology proposed to describe the thermal decomposition behavior, and evolved volatile analysis of vegetative fuels using the TG-FTIR technique. Experiments within this method include testing the usual grinded form of samples compared to the intact form, which can render reliable and useful information to improve the understanding of the ignitability and combustibility of forest fuels. Moreover, slow (20 and 40 °C/min) and quasi-fast (60, 80 and 100 °C/min) heating rates were chosen to get close from the actual conditions of wildland fires (preheating/smoldering and flame region, respectively). In this work, we report the thermal decomposition behavior under inert (N2) and oxidative (air) atmospheres of Genista Salzmannii Needles (GSN) involved in high-intensity fires of Mediterranean forests. The results showed that the intact GSN were characterized by a higher mass loss rate compared to the grinded GSN. Furthermore, TG analyses were performed to assess thermal reactivity and combustion indices (ignition, devolatilization, combustion and burnout indices) of grinded and cut GSN samples at fives heating rates. The used set of the thermal indices are important properties to be determined when talking about efficient wildland fire management. As the heating rate increases, reactivity and combustion indices increase linearly. At low heating rates (20 and 40 °C/min), these parameters were quite similar for both samples, while the gap becomes more and more significant at elevated heating rates (60, 80 and 100 °C/min). High correlation coefficients (R2 > 0.96) were obtained, which indicate a good degree of fitting reliability between combustion characteristics and the tested heating rates. The determined slope can be used to compare and classify ignitability and combustibility of vegetative fuels related to fire risk potential. Based on the 3D-FTIR spectra, the dominant gases released during pyrolysis were CO2, C=O bond, C-H and CO bond and H2O, while during combustion, CO2 and H2O were the major products. For kinetic investigations, activation energy (Ea) was calculated by means of two isoconversional methods. The variation of Ea with the conversion rate has exhibited a quite similar behavior during the whole pyrolysis and combustion process. Char formation, at the end of an intense devolatilization, was the most complex process. The oxidation of the remaining char was characterized by a significant decrease of Ea and thus it was not considered as a major event in the combustion process.

HAL (Le Centre pour la Communication Scientifique Directe), Dec 13, 2021

Advances in forest fire research 2018

A navegação consulta e descarregamento dos títulos inseridos nas Bibliotecas Digitais UC Digitali... more A navegação consulta e descarregamento dos títulos inseridos nas Bibliotecas Digitais UC Digitalis, UC Pombalina e UC Impactum, pressupõem a aceitação plena e sem reservas dos Termos e Condições de Uso destas Bibliotecas Digitais, disponíveis em https://digitalis.uc.pt/pt-pt/termos. Conforme exposto nos referidos Termos e Condições de Uso, o descarregamento de títulos de acesso restrito requer uma licença válida de autorização devendo o utilizador aceder ao(s) documento(s) a partir de um endereço de IP da instituição detentora da supramencionada licença. Ao utilizador é apenas permitido o descarregamento para uso pessoal, pelo que o emprego do(s) título(s) descarregado(s) para outro fim, designadamente comercial, carece de autorização do respetivo autor ou editor da obra. Na medida em que todas as obras da UC Digitalis se encontram protegidas pelo Código do Direito de Autor e Direitos Conexos e demais legislação aplicável, toda a cópia, parcial ou total, deste documento, nos casos em que é legalmente admitida, deverá conter ou fazer-se acompanhar por este aviso.

Journal of Thermal Analysis and Calorimetry, 2014

Advances in forest fire research, 2014

Fuel, 2012

Advanced knowledge of the mechanisms and kinetic parameters controlling the thermal decomposition... more Advanced knowledge of the mechanisms and kinetic parameters controlling the thermal decomposition of peat is of importance for understanding smouldering peat fires and quantify fire risk. Smouldering fires not have the visual impact of the flaming front but constitute an important wildfire phenomenon because of the associated large carbon emissions and damage to a valuable ecosystem. Moreover, in case of extreme dry conditions or strong winds, smouldering fires develop easily into scrub or forest flaming fire. In this context, a thermal study on three different types of peat has been conducted: two high-moor peat types collected in Edinburgh (Scotland) and in Tomsk (Siberia), and one transition peat from Tomsk. The botanical composition, degree of decomposition and ultimate analysis were determined for the different samples and compared. These parameters were correlated to thermal behavior obtained by Thermogravimetry experiments. Significnalty different degradation behavior is observed for the different peat types. A kinetic method to predict the temperature of the sample at high heating rates is applied. Comparison shows a good correlation between experimental and numerical results.

Fire Safety Journal, 2013

Mass loss is a significant factor in fire modeling. In this work, 4 Mediterranean species were st... more Mass loss is a significant factor in fire modeling. In this work, 4 Mediterranean species were studied in order to identify thermal degradation mechanisms. These parameters were correlated to thermal behavior obtained by thermogravimetry experiments, with investigations conducted on samples of the 4 species. A scientific software tool developed by chemists, which provides the bench scientist with an easy-to-use, rapid and interactive method for accurate simulations of thermal degradation mechanisms, is of relevance to this context. The software platform WinGPYRO, developed in this study, allows the determination of a set of kinetic parameters (activation energy, pre-exponential factor and model schemes) by application of a Kinetic Hybrid Method (KHM). Kinetic schemes were processed in WinGPYRO, which manages and facilitates comparisons of both numerical results and experimental data. Simulation was based on Gpyro, an open-source computer model, which describes the thermal response of solid materials exposed to radiative or convective heating, including thermo-oxidative pyrolysis of the condensed phase.

Journal of Analytical and Applied Pyrolysis

Coal and Peat Fires: a Global Perspective, 2015

Peat is an organic and flammable material used for energy generation and involved in wildfires. S... more Peat is an organic and flammable material used for energy generation and involved in wildfires. Smoldering fires do not have the visual impact of flaming fronts but are an important aspect of wildfires because of the associated large carbon emissions and damage to valuable ecosystems. Moreover, in the case of extreme dry conditions or strong winds, smoldering fires develop easily into scrub or forest flaming fires. An advanced knowledge on the mechanisms and kinetic parameters controlling the drying process and the thermal decomposition of peat is of importance for understanding smoldering peat fires and quantifying the associated risks. In this context, the present chapter proposes a contribution to determine kinetic parameters to model peat-fire hazard. Three main topics were developed: thermal behavior, kinetic analysis, and fire hazard modeling. 1. Investigations were conducted on boreal peat samples from two regions (Scotland and Siberia) and for three depths: two high-moor peat types collected in Edinburgh and in Tomsk, and one transition peat from Tomsk. For each sample, the botanical composition, degree of decomposition, ultimate analysis, and moisture content were determined and correlated to the thermal behavior obtained using two thermal apparatuses: a Thermogravimetric Analyzer and a Differential Scanning Calorimeter, along with a humidity analyzer. The complementary use of these thermal techniques provides details about the partial processes and reaction kinetics. The peat samples were submitted to thermal stress from the ambient temperature to 773 K with heating rates of 10, 20, and 30 K/min. A significantly different degradation behavior was observed for the different peat types. However, three main degradation steps can be isolated. The first one consists of a drying step between ambient temperature and 473 K, the second one is a devolatilization step between 473 and 650 K, and last one is a combustion step from 650 to 773 K. A large part of this chapter is dedicated to the description of these phenomena and their correlations with the various physicochemical, botanical, and physiological parameters of the peat previously determined. 2. Based on the experimental results, another part of the chapter is devoted to the determination of kinetic constants. The kinetic triplet of each reaction involved during thermal degradation was estimated. Water evaporation is known to be an important mechanism that dictates the ignition and spread of peat fires. In this context, the thermokinetic constants for drying were determined using two different methods: the Inverse Kinetic Problems and Kissinger Akahira Sunose methods. Moreover, it is well known that devolatilization conditions have a major bearing on the yield of char and its reactivity in the process. This evidence, together with the need to develop models that predict peat behavior when it is subjected to a heating process, confers a great interest on the kinetic study of smoldering and combustion. For these two complex exothermic phenomena, the kinetic triplets of each reaction were estimated using a more detailed Hybrid Kinetic Method. This method has the advantage of eliminating errors caused by the ambiguity of the phenomenon. 3. Despite the negative impact of peat fires, a science-based system has not yet been developed for the prediction of their occurrence. Such a method would allow one to assess the probability of occurrence of peat fire, taking into account the natural and anthropogenic pressure, weather conditions, terrain characteristics, and dynamics of the moisture content of the peat layer. Therefore, the description of peat drying is a major parameter in the prediction of fire danger. The last part of the chapter devoted to the development of a mathematical model of the drying of a peat layer is based on a single temperature. The iteration–interpolation method was used to numerically solve the mathematical model. The thermokinetic constants previously obtained were used to implement the simulations. The model allows one to obtain the time variation of the volume fraction of water, gas phase, and temperature of the peat layer. To conclude, an accurate set of mathematical models that can be used for predicting peat-fire hazard is presented. These models take into account all known reasons for ignition of natural fires. The specific meteorological conditions, anthropogenic pressure, and simulation of the dynamics of the moisture content of the peat layer are included in the analysis.

The estimation of the heat radiated by the flame front is of primary importance for improving the... more The estimation of the heat radiated by the flame front is of primary importance for improving the safety of people or structures in the vicinity of wildland fires. This article presents the development of a new flame model used to calculate the radiative impact of a wildfire. The model is based on the solid flame assumption. The new feature, compared to existing literature, is to consider a finite fire front width. The realistic description of finite fire front width allows proposing a new criterion for the estimation of the radiative impact of the fire, which is based on the ratio fire front width / fire front height. As the model needs to be solved numerically, an analytical approximation is proposed to obtain a simple and useful formulation of the Safety Distance. A sensivity analysis is conducted on the different physical and geometrical parameters used to define the flame front. It shows that the flame temperature is the most sensitive parameter. The results of the proposed mod...

Climate change causes more frequent and destructive wildfires even transforming them into megafir... more Climate change causes more frequent and destructive wildfires even transforming them into megafire. Moreover, all biomass fires produce emissions of carbon compounds in the form of soot to the atmosphere with a significant impact on the environment and human health. Indeed, the soot is causing the formation of PAHs from (a) the high temperature thermal alteration of natural product precursors in the source organic matter and (b) the recombination of molecular fragments in the smoke. However, these molecules are known to have carcinogenic effects on human health. It is therefore interesting to quantify the 16 PAHs concentration extracted from soot emitted in open diffusion flame of biomass combustion. To achieve this objective, an analytical method developed for the study of kerosene combustion has been adapted for soot from biomass. This new method allowed to quantify the 16 PAHs defined as priority pollutants by the US EPA for their carcinogenic mutagenic effect and on human health.

The aim of this work is to study the NO emissions under typical wildland fires conditions, paying... more The aim of this work is to study the NO emissions under typical wildland fires conditions, paying special attention to the effect of the fuel-bound nitrogen. For this purpose, numerical simulations have been run using the PSR code from the CHEMKIN II package with a full mechanism (GDF-Kin® 3.0). Fuel bound-nitrogen has been included in the pyrolysis gaseous mixture of vegetation as NH3. Results have shown that if fuel-nitrogen is not considered on the pyrolysis mixture, NO emissions in wildland fire conditions are strongly under-estimated. Simulations results have been compared to experimental data.

Natural Hazards and Earth System Science, 2014

Combustion Science and Technology, 2012

This article may be used for research, teaching, and private study purposes. Any substantial or s... more This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.