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Chimney effect induced by smoldering fire in a U-shaped porous channel: A governing mechanism of the persistent underground coal fires

Song, Zeyang and Huang, Xinyan and Künzer, Claudia and Zhu, Hongqinq and Jiang, Juncheng and Pan, Xuhai and Zhong, Xiaoxing (2020) Chimney effect induced by smoldering fire in a U-shaped porous channel: A governing mechanism of the persistent underground coal fires. Process Safety and Environmental Protection, 136, pp. 136-147. Institution of Chemical Engineers. DOI: 10.1016/j.psep.2020.01.029 ISSN 0957-5820

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Official URL: https://www.sciencedirect.com/science/article/abs/pii/S0957582019322414

Abstract

This paper presents underground coal fires (UCF) induced natural ventilation through a U-shaped porous channel. Height of the U-shaped channel (the fire depth) is one of key elements determining the accessibility of air supply to UCF. Conventionally, we acknowledge that under the external wind driving force, air supply to underground space should decay with increasing the fire depth. However, under the thermal buoyancy force induced by UCF, responses of air supply and UCF to the fire depth are uncertain. Herein we propose a 1/20-scale experimental framework to measure air velocity, and to quantify the burning rate, the fire spread rate and the burning temperature of UCF at different fire depths (H = 1.6–4.6 m) with variable aperture sizes (Φ = 1–4 cm). A one-dimensional model correlating the air velocity with the fire depth is validated and then extrapolates laboratory-scale free channels into field-scale (H = 100 m) percolation channels. We find the ‘chimney effect’ – air supply driven by the buoyant smoke of UCF is unexpectedly enhanced with increasing the fire depth; the enhanced air supply due to the chimney effect facilitates burning of coal. The chimney effect, serving as a self-sustaining mechanism of air supply to UCF, is a significant governing mechanism for persistent UCF burning for hundreds or even thousands of years.

Item URL in elib:https://elib.dlr.de/134161/
Document Type:Article
Title:Chimney effect induced by smoldering fire in a U-shaped porous channel: A governing mechanism of the persistent underground coal fires
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Song, Zeyangzeyang.song (at) njtech.edu.cnUNSPECIFIED
Huang, Xinyanxy.huang (at) polyu.edu.hkUNSPECIFIED
Künzer, ClaudiaClaudia.Kuenzer (at) dlr.deUNSPECIFIED
Zhu, HongqinqChina University of Mining and Technology, BeijingUNSPECIFIED
Jiang, JunchengNanjing Tech University, ChinaUNSPECIFIED
Pan, XuhaiNanjing Tech University, ChinaUNSPECIFIED
Zhong, Xiaoxingzhxxcumt (at) 163.comUNSPECIFIED
Date:30 January 2020
Journal or Publication Title:Process Safety and Environmental Protection
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:136
DOI :10.1016/j.psep.2020.01.029
Page Range:pp. 136-147
Publisher:Institution of Chemical Engineers
ISSN:0957-5820
Status:Published
Keywords:Natural ventilation; Thermal buoyancy; Subsurface fire; Stack effect
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Erdbeobachtung
DLR - Research theme (Project):R - Remote sensing and geoscience
Location: Oberpfaffenhofen
Institutes and Institutions:German Remote Sensing Data Center > Land Surface Dynamics
Deposited By: Varga, Monica-Marieta
Deposited On:23 Apr 2020 14:56
Last Modified:27 Apr 2020 11:55

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