Nikola Mišić, Milan Protić, Artemi Cerdà, Miomir Raos, Milan Blagojević
{"title":"Transition from Surface to Crown Fires: Effects of Moisture Content","authors":"Nikola Mišić, Milan Protić, Artemi Cerdà, Miomir Raos, Milan Blagojević","doi":"10.1007/s10694-023-01525-1","DOIUrl":null,"url":null,"abstract":"<div><p>With climate change and the ever-drier climate, the issue of wildfires is becoming increasingly prominent, generating growing interest in the study of wildfires. The majority of the ongoing research is focused on surface wildland fuels with particular emphasis on dead and usually dry fuel. These insights are difficult to transpose to live fuels, particularly to crown fires. The flammability properties of dead and dry forest fuels are of little significance for understanding the onset and spread of crown fires. Hence, research regarding the flammability properties of fresh forest vegetation is very sparse. The same observation applies to crown fires, despite the fact that this type of wildfires is devastating, difficult to suppress, and usually having dramatic consequences. The aim of this paper is to determine how moisture dynamics of live crown samples (terminal parts of basal branches) of two coniferous species, <i>Abies alba</i> and <i>Picea abies</i>, influence their flammability properties. Experiments were performed in an adapted mass loss calorimeter with a custom-made sample holder in order to mimic the scenario of initiation of crown fires (surface to crown fire interface). Tests were performed with heat flux values of 50, 60, and 70 kW/m<sup>2</sup> and with different moisture levels. At all heat flux values, the results show an increasing trend for the peak heat release rate when moisture content is reduced. <i>A. alba</i> samples reach higher peak release rates in comparison with <i>P. abies</i> samples. At heat fluxes of 50 kW/m<sup>2</sup> and 60 kW/m<sup>2</sup>, fresh <i>A. alba</i> samples take longer to ignite than the <i>P. abies</i> samples. At the heat flux of 70 kW/m<sup>2</sup>, for the set of analyzed moisture contents, the ignition time interval for the <i>A. alba</i> samples is shorter than for the <i>P. abies</i> samples. The results of the principal component analysis (PCA) show that variables such as time to ignition (TTI), peak heat release rate (PHRR), and mean heat release rate (mean HRR) best describe the ignitability of the analyzed conifer samples.</p></div>","PeriodicalId":558,"journal":{"name":"Fire Technology","volume":null,"pages":null},"PeriodicalIF":2.3000,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Fire Technology","FirstCategoryId":"5","ListUrlMain":"https://link.springer.com/article/10.1007/s10694-023-01525-1","RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENGINEERING, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
With climate change and the ever-drier climate, the issue of wildfires is becoming increasingly prominent, generating growing interest in the study of wildfires. The majority of the ongoing research is focused on surface wildland fuels with particular emphasis on dead and usually dry fuel. These insights are difficult to transpose to live fuels, particularly to crown fires. The flammability properties of dead and dry forest fuels are of little significance for understanding the onset and spread of crown fires. Hence, research regarding the flammability properties of fresh forest vegetation is very sparse. The same observation applies to crown fires, despite the fact that this type of wildfires is devastating, difficult to suppress, and usually having dramatic consequences. The aim of this paper is to determine how moisture dynamics of live crown samples (terminal parts of basal branches) of two coniferous species, Abies alba and Picea abies, influence their flammability properties. Experiments were performed in an adapted mass loss calorimeter with a custom-made sample holder in order to mimic the scenario of initiation of crown fires (surface to crown fire interface). Tests were performed with heat flux values of 50, 60, and 70 kW/m2 and with different moisture levels. At all heat flux values, the results show an increasing trend for the peak heat release rate when moisture content is reduced. A. alba samples reach higher peak release rates in comparison with P. abies samples. At heat fluxes of 50 kW/m2 and 60 kW/m2, fresh A. alba samples take longer to ignite than the P. abies samples. At the heat flux of 70 kW/m2, for the set of analyzed moisture contents, the ignition time interval for the A. alba samples is shorter than for the P. abies samples. The results of the principal component analysis (PCA) show that variables such as time to ignition (TTI), peak heat release rate (PHRR), and mean heat release rate (mean HRR) best describe the ignitability of the analyzed conifer samples.
期刊介绍：
Fire Technology publishes original contributions, both theoretical and empirical, that contribute to the solution of problems in fire safety science and engineering. It is the leading journal in the field, publishing applied research dealing with the full range of actual and potential fire hazards facing humans and the environment. It covers the entire domain of fire safety science and engineering problems relevant in industrial, operational, cultural, and environmental applications, including modeling, testing, detection, suppression, human behavior, wildfires, structures, and risk analysis.
The aim of Fire Technology is to push forward the frontiers of knowledge and technology by encouraging interdisciplinary communication of significant technical developments in fire protection and subjects of scientific interest to the fire protection community at large.
It is published in conjunction with the National Fire Protection Association (NFPA) and the Society of Fire Protection Engineers (SFPE). The mission of NFPA is to help save lives and reduce loss with information, knowledge, and passion. The mission of SFPE is advancing the science and practice of fire protection engineering internationally.
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