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The Impact of Environmental Conditions on Methane-Air Explosion Development and Propagation Through Rock Rubble in Confined Spaces.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	The Impact of Environmental Conditions on Methane-Air Explosion Development and Propagation Through Rock Rubble in Confined Spaces./
Author:	Fig, Matt K.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2019,
Description:	221 p.
Notes:	Source: Dissertations Abstracts International, Volume: 80-09, Section: B.
Contained By:	Dissertations Abstracts International80-09B.
Subject:	Mechanical engineering. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=13427433
ISBN:	9780438938908

The Impact of Environmental Conditions on Methane-Air Explosion Development and Propagation Through Rock Rubble in Confined Spaces.
Fig, Matt K.

The Impact of Environmental Conditions on Methane-Air Explosion Development and Propagation Through Rock Rubble in Confined Spaces. - Ann Arbor : ProQuest Dissertations & Theses, 2019 - 221 p.

Source: Dissertations Abstracts International, Volume: 80-09, Section: B.

Thesis (Ph.D.)--Colorado School of Mines, 2019.

This item must not be added to any third party search indexes.

Methane-driven explosions in underground coal mines are among the largest and deadliest industrial explosions. Over the period from 1980-2012, CDC statistics reveal that more than 150 people died in coal mine explosions in the United States alone, with well over double that number of deaths worldwide. Coal is likely to continue as a worldwide source of power well into the future, so it is imperative to human life that these explosions are prevented where potential exists and mitigated when explosive potential is realized. One approach to this task is to build an understanding of large-scale explosions from a foundational knowledge of explosions at smaller scales, with the goal of providing explosion hazard information to mine designers and operators. Such an understanding can be gained by coupled experimentation and modeling of (relatively) smaller explosions. The goal of this study was to develop a fuller understanding of the impact of specific factors and conditions found in a mine, as needed for better predictive explosion models that use Computational Fluid Dynamics (CFD) with combustion kinetics. A CFD ventilation model of a longwall coal mine, when augmented by an accurate combustion model, can aid the analysis of a ventilation scheme to both predict zones of accumulated explosive gas mixtures and give insight into the expected severity in the event one of these zones ignites. Combined models are also likely to advance a post-explosion assessment of antecedent causes. The conditions that create the possibility of a CH4 explosion include factors contingent upon the chemical and thermodynamic properties of the gas mixture, such as temperature, pressure, mass of available fuel, and the air-fuel ratio of the mixture. However, these quantities do not completely describe confined explosions. Other factors include the nature of the confining geometry, the temperature and surface conditions of all bounding walls, the presence of obstacles and their locations, and the presence of humidity. The horizontal cylindrical reactor vessels were developed to investigate these factors and conditions at different scales was. These vessels allow for the controlled examination of CH4-air combustion experiments, and include reactors with volumes of 8.4L, 5.7L, 18.4L, 22L at the laboratory scale, and a 2400L volume reactor for field-scale explosion testing. Two of these reactors are made of quartz glass and give the capability to visually examine CH4 flame interaction with simulated obstacles, such as the rock piles found in the gob area of a coal mine. Experiments performed with these reactors are meant to give some confidence in extrapolated predictions for large-scale explosions in confined spaces since full-scale explosion experiments are impractical to carry out. Experiments have been conducted to produce insight into the impact of stoichiometry, reactor diameter, rock material type, rock pile permeability, rock barrier length, gas moisture content, rock barrier height, and rock pile position on flame development. Of primary interest is the flame front propagation velocity (SB), since this is a key indicator of the transition to turbulence and, under the right conditions, the further transition to detonation. Concurrent numerical combustion simulations were performed using ANSYS Fluent. These included 2D Computational Fluid Dynamics (CFD) coupled with a 2-step kinetics combustion model for the simulated reactors with obstacles to correspond with the experimental efforts. Rock piles are found to increase S B when placed in any location, with most reactors producing the largest velocities when rocks are placed near the closed end with ignition at the closed end. Taller rock piles are found to produce faster flames. The inclusion of humidity is found to slow the propagation of methane flames. The coupled 2D CFD and combustion model captures these features semi-quantitatively and shows that the increase in turbulent transport associated with the rock piles explains the faster SB. The model has been developed thoroughly for the laboratory reactors, and the first steps towards larger and 3D implementation have been taken.

ISBN: 9780438938908Subjects--Topical Terms:

557493
Mechanical engineering.
Subjects--Index Terms:

Flame front propagation velocity

The Impact of Environmental Conditions on Methane-Air Explosion Development and Propagation Through Rock Rubble in Confined Spaces.
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500 $a Source: Dissertations Abstracts International, Volume: 80-09, Section: B.
500 $a Publisher info.: Dissertation/Thesis.
500 $a Advisor: Bogin, Gregory;Brune, Jurgen.
502 $a Thesis (Ph.D.)--Colorado School of Mines, 2019.
506 $a This item must not be added to any third party search indexes.
506 $a This item must not be sold to any third party vendors.
520 $a Methane-driven explosions in underground coal mines are among the largest and deadliest industrial explosions. Over the period from 1980-2012, CDC statistics reveal that more than 150 people died in coal mine explosions in the United States alone, with well over double that number of deaths worldwide. Coal is likely to continue as a worldwide source of power well into the future, so it is imperative to human life that these explosions are prevented where potential exists and mitigated when explosive potential is realized. One approach to this task is to build an understanding of large-scale explosions from a foundational knowledge of explosions at smaller scales, with the goal of providing explosion hazard information to mine designers and operators. Such an understanding can be gained by coupled experimentation and modeling of (relatively) smaller explosions. The goal of this study was to develop a fuller understanding of the impact of specific factors and conditions found in a mine, as needed for better predictive explosion models that use Computational Fluid Dynamics (CFD) with combustion kinetics. A CFD ventilation model of a longwall coal mine, when augmented by an accurate combustion model, can aid the analysis of a ventilation scheme to both predict zones of accumulated explosive gas mixtures and give insight into the expected severity in the event one of these zones ignites. Combined models are also likely to advance a post-explosion assessment of antecedent causes. The conditions that create the possibility of a CH4 explosion include factors contingent upon the chemical and thermodynamic properties of the gas mixture, such as temperature, pressure, mass of available fuel, and the air-fuel ratio of the mixture. However, these quantities do not completely describe confined explosions. Other factors include the nature of the confining geometry, the temperature and surface conditions of all bounding walls, the presence of obstacles and their locations, and the presence of humidity. The horizontal cylindrical reactor vessels were developed to investigate these factors and conditions at different scales was. These vessels allow for the controlled examination of CH4-air combustion experiments, and include reactors with volumes of 8.4L, 5.7L, 18.4L, 22L at the laboratory scale, and a 2400L volume reactor for field-scale explosion testing. Two of these reactors are made of quartz glass and give the capability to visually examine CH4 flame interaction with simulated obstacles, such as the rock piles found in the gob area of a coal mine. Experiments performed with these reactors are meant to give some confidence in extrapolated predictions for large-scale explosions in confined spaces since full-scale explosion experiments are impractical to carry out. Experiments have been conducted to produce insight into the impact of stoichiometry, reactor diameter, rock material type, rock pile permeability, rock barrier length, gas moisture content, rock barrier height, and rock pile position on flame development. Of primary interest is the flame front propagation velocity (SB), since this is a key indicator of the transition to turbulence and, under the right conditions, the further transition to detonation. Concurrent numerical combustion simulations were performed using ANSYS Fluent. These included 2D Computational Fluid Dynamics (CFD) coupled with a 2-step kinetics combustion model for the simulated reactors with obstacles to correspond with the experimental efforts. Rock piles are found to increase S B when placed in any location, with most reactors producing the largest velocities when rocks are placed near the closed end with ignition at the closed end. Taller rock piles are found to produce faster flames. The inclusion of humidity is found to slow the propagation of methane flames. The coupled 2D CFD and combustion model captures these features semi-quantitatively and shows that the increase in turbulent transport associated with the rock piles explains the faster SB. The model has been developed thoroughly for the laboratory reactors, and the first steps towards larger and 3D implementation have been taken.
590 $a School code: 0052.
650 4 $a Mechanical engineering. $3 557493
653 $a Flame front propagation velocity
653 $a Predictive explosion models
653 $a Underground coal mines
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710 2 $a Colorado School of Mines. $b Mechanical Engineering. $3 1241272
773 0 $t Dissertations Abstracts International $g 80-09B.
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791 $a Ph.D.
792 $a 2019
793 $a English
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