A numerical model for the determination of biomass ignition from a hotspot
Date
2015
Authors
McArdle, Patrick, author
Williams, John, advisor
Gao, Xinfeng, committee member
Shipman, Patrick, committee member
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Abstract
The determination of biomass ignition from an inert spherical hotspot using a fourth-order finite-volume method is presented. The transient ignition-combustion system is modeled by two coupled reaction-diffusion equations. One equation governs the heating characteristics of the biomass while the other governs the mass loss of the biomass. The combustion assumes a one-step, 1st-order Arrhenius reaction. This work is motivated and funded by the Department of Defense Legacy Program to create a munition specific fire danger rating system. Improving fire danger rating systems on military lands would minimize the economic and environmental impact of soldiers training on protected habitats. A better understanding of these ignition characteristics would also improve current fire spread models. Our result shows that given the ignition criteria derived from a simplified non-dimensional model and specifying critical values found by Gol'dshleger et al., an ignition probability can be established by varying the biomass properties based on moisture content. Following the procedure developed in this thesis, the computed ignition probabilities correlate well with experimental ignition data that was obtained at the Center for Environmental Management of Military Lands. Moreover, numerically solving the coupled reaction-diffusion system provides additional insight into more realistic ignition criteria involving mass loss. The numerical solution suggests more sources of heat loss, in addition to convection, must be considered for a more realistic ignition model.
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Subject
biomass combustion
finite-volume method
hotspot ignition
reaction-diffusion