Charring shrinkage and cracking of fir during pyrolysis in inert atmosphere and different ambient pressures

Kaiyuan Li, Simo Hostikka, Peng Dai, Yuanzhou Li, Heping Zhang, Jie Ji

Research output: Contribution to journalArticle

20 Citations (Scopus)


A set of pyrolysis experiments were conducted on fir in inert atmosphere and different ambient pressures, to investigate the char shrinkage and cracking during combustion. The results show that the grain effect influences the char shrinkage. The shrinkage parallel to grain is only 1/4 of the shrinkage perpendicular to grain. The strong restriction on shrinkage parallel to grain leads to the major cracking perpendicular to the grain direction, whereas the cracking parallel to grain is relatively weak with only shallow and random fissures produced. The shrinkage gradient at cracking time increases with increasing heat flux and decreasing ambient pressure while the surface density behaves oppositely. The number of fissures is strongly affected by these two parameters and an empirical correlation is developed for predicting the number of fissures. Increasing the ambient pressure will enhance shrinkage, leading to early cracking with relatively low shrinkage gradient. Under the current experimental conditions, the occurrence of cracking requires a shrinkage gradient greater than 35 m −1 and a surface density lower than 0.8 of the original density.
Original languageEnglish
Pages (from-to)3185–3194
Number of pages10
JournalProceedings of the Combustion Institute
Issue number2
Early online date2016
Publication statusPublished - 2017
MoE publication typeA1 Journal article-refereed


  • Wood
  • Cracking
  • Shrinkage
  • Ambient pressure
  • Pyrolysis

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