Tianyang Chu , Chuangang Fan , Chunli Liu , Saiya Feng , Zhengyang Wang , K.M. Liew
{"title":"Effect of structural characteristics on charring shrinkage and cracking of densified wood under radiative heatings","authors":"Tianyang Chu , Chuangang Fan , Chunli Liu , Saiya Feng , Zhengyang Wang , K.M. Liew","doi":"10.1016/j.firesaf.2024.104204","DOIUrl":null,"url":null,"abstract":"<div><p>Densified wood (DW) is a novel engineering material with excellent mechanical properties. It forms a thermally insulating and hardly-cracked char layer during pyrolysis and combustion. However, the scientific fundamentals regarding how wood structural characteristics (e.g. density) affect its charring behavior remain unknown, which is important for the fire safety of wood. In this work, the charring shrinkage and cracking of NW and DW with various densities (<em>ρ</em>) under heating exposures (<em>Q</em><sub><em>r</em></sub>) are investigated and analyzed. Partial crack closure was observed due to the oxidation. As wood <em>ρ</em> increases or <em>Q</em><sub><em>r</em></sub> decreases, the number of cracks (<em>N</em><sub><em>c</em></sub>) decreases and cracking time (<em>t</em><sub><em>c</em></sub>) is delayed because both the surface temperature (<em>T</em><sub><em>surf</em></sub>) and altered thermal stress concentrations on the wood surface are reduced. DW presents an earlier mass loss peak and lower peak value due to the delignification. DW presents high fluctuations in <em>T</em><sub><em>surf</em></sub> due to the combing effect of thermal inertia and radial rebound. As wood <em>ρ</em> increases, char shrinkage depth at <em>t</em><sub><em>c</em></sub> decreases and shrinkage gradient at <em>t</em><sub><em>c</em></sub> increases first and then decreases. An empirical correlation is proposed and well-predicts the <em>N</em><sub><em>c</em></sub> based on <em>ρ</em> and <em>Q</em><sub><em>r</em></sub>. It can be potentially implemented in the combustion model to improve prediction accuracy.</p></div>","PeriodicalId":50445,"journal":{"name":"Fire Safety Journal","volume":null,"pages":null},"PeriodicalIF":3.4000,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Fire Safety Journal","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0379711224001176","RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENGINEERING, CIVIL","Score":null,"Total":0}
引用次数: 0
Abstract
Densified wood (DW) is a novel engineering material with excellent mechanical properties. It forms a thermally insulating and hardly-cracked char layer during pyrolysis and combustion. However, the scientific fundamentals regarding how wood structural characteristics (e.g. density) affect its charring behavior remain unknown, which is important for the fire safety of wood. In this work, the charring shrinkage and cracking of NW and DW with various densities (ρ) under heating exposures (Qr) are investigated and analyzed. Partial crack closure was observed due to the oxidation. As wood ρ increases or Qr decreases, the number of cracks (Nc) decreases and cracking time (tc) is delayed because both the surface temperature (Tsurf) and altered thermal stress concentrations on the wood surface are reduced. DW presents an earlier mass loss peak and lower peak value due to the delignification. DW presents high fluctuations in Tsurf due to the combing effect of thermal inertia and radial rebound. As wood ρ increases, char shrinkage depth at tc decreases and shrinkage gradient at tc increases first and then decreases. An empirical correlation is proposed and well-predicts the Nc based on ρ and Qr. It can be potentially implemented in the combustion model to improve prediction accuracy.
期刊介绍:
Fire Safety Journal is the leading publication dealing with all aspects of fire safety engineering. Its scope is purposefully wide, as it is deemed important to encourage papers from all sources within this multidisciplinary subject, thus providing a forum for its further development as a distinct engineering discipline. This is an essential step towards gaining a status equal to that enjoyed by the other engineering disciplines.