Smoldering Fire


Smoldering combustion is the slow, low temperature, flameless burning of porous fuels and the most persistent type of combustion phenomena. The heat is released when oxygen directly attacks the surface of a solid fuel. It is especially common in porous fuels which form a char on heating, like cigarette, wood, plastic foam, coal, and peat soil. For example, after the collapse of the Word Trade Center towers on 11/9/2001, the immense piles of debris smoldered for 3–5 months in the middle of one of the most heavily populated cities of the world, resisting all suppression attempts until the slow removal of debris cleared the pile. Smoldering combustion is among the leading causes of residential fires because of releasing massive CO.

Smoldering is also the dominant combustion phenomena in wildfires of natural deposits of peat and coal which are the largest and longest burning fires on Earth. The oldest fire on Earth is The Burning Mountain in New South Wales, Australia, a large coal seam which has been smoldering for more than 6000 years. Recent research shows that peat fire produces 15% of the global carbon emission. Our research now focuses on:

  • Smoldering peat fire

  • Smoldering Ignition and extinction limits

  • Numerical Simulation of smoldering combustion

  • Smoldering fire suppression technologies


  • Research and development of organic waste removal technology via smoldering and emission control strategy, Curriculum Vitae of Xinyan Huang (May 2020) 4 Cooperation Fund of Sichuan (2019YFSY0040), RMB 200K, 2019 - 2021

  • Smoldering Ignition and Quenching Criteria: Interactions between Heat-and-Mass Transfer and Heterogeneous Reactions under Limiting Conditions, NSFC General Fund (No. 51876183), RMB 600K, 2019 - 2022


Representative publications:

[1] S. Lin, X. Huang (2021) Quenching of Smoldering: Effect of Wall Cooling on Extinction, Proc Combust Inst (in press) 

[2] S. Lin, Y.K. Cheung, Y. Xiao, X. Huang (2020) Can Rain Suppress Smoldering Peat Fire? Sci Total Environ, 138468.

[3] S. Lin, P. Sun, X. Huang* (2019) Can Peat Soil Support a Flaming Wildfire? Intl J Wildland Fire, 28(8): 601-613.

[4] Q. Xie, Z. Zhang, S. Lin, Y. Qu, X. Huang (2020) Smoldering fire of high-density cotton bale under concurrent wind, Fire Technol, 56(4), 2241–2256.

[5] Z. Song, X. Huang, C. Kuenzer, H. Zhu, J. Jiang, X. Pan, X. Zhong (2020) Chimney effect induced by smoldering fire in a U-shaped porous channel: A governing mechanism of the persistent underground coal fires, Proc Safety Environ Protect, 136, 136–47.

[6] J. Wang, W. Xing, X. Huang, X. Jin, H. Yu, J. Wang, L. Song, W. Zeng, Y. Hu, Smoldering of storage rice: Effect of moldy degree and moisture content, Combust Sci Tech.

[7] X. Huang, G. Rein (2019) Upward-and-downward Spread of Smoldering Peat Fire, Proc Combust Inst, 37: 4025–4033

[8] Z. Song, X. Huang, J. Jiang, X. Pan (2020) A laboratory approach to CO2 and CO emission factors from underground coal fires, Intl J Coal Geology, 219, 103382. 

[9] X. Huang, G. Rein (2017) Downward Spread of Smoldering Peat Fire: the Role of Moisture, Density and Oxygen Supply, Intl J Wildland Fire, 26, 907-918.

[10] H. Yuan, X. Huang, G. Rein (2018) Gpyro Workbook on Pyrolysis & Smouldering Problems. DOI: 10.5281/zenodo.1212540

[11] M.A. Santoso, X. Huang, N. Prat, E. Christensen, Eirik; Y. Hu, G. Rein (2019) Smouldering Fires and Soils, Chapter 14, Fire Effects on Soil Properties (P. Pereira Ed.), CSIRO Publishing, 203-216.


Project members:

Shaorun Lin

Yuying Chen

©2020 by PolyU Fire Lab.