Transport Effects on Calorimetry of Porous Wildland Fuels
Date
2008Author
Schemel, Christopher
Metadata
Abstract
Wildland fire is a natural part of the earth’s phenomenological pattern and like
most natural phenomena has presented a challenge to human activity and
engineering science. Wildfire presents Fire Safety Engineering with the task of
developing fundamental research and designing analysis tools to address fire on a
scale where interactions with atmospheric and terrestrial conditions dominate fire
behavior. The research work presented in this thesis addresses a fundamental
research issue involving transport processes in porous wildland fuel beds. This
research project had the specific goal of developing an understanding of how
transport processes affected the combustion of wildland fuels that were in the
form of a porous bed. No detailed study could be found in the literature that
specifically addressed how the fuel structure affected the combustion process in
these types of fuels. To this end, a series of experiments were designed and
carried out that approached the understanding of this problem using commonly
available fire testing equipment, specifically the cone calorimeter and the FM
Global Fire Propagation Apparatus. The goal of this research study and the basis
for the novel and relevant contribution to the field of engineering was to conduct
an experimental test series, analyze the data and examine the scalability of the
results, to determine the effect of transport processes on the Heat Release Rate
(HRR) of porous wildland fuels. The project concluded that flow dominates HRR
in fires involving the wildland fuels tested. A dimensionless analysis of the fuel
sample baskets showed consistency with well established mass transfer, fluid flow
and chemical kinetic relationships. The dimensionless analysis also indicates that
the experimental results should be scalable to similar configurations in larger fuel
beds. One conclusion of this study was that wildland fire modeling efforts should
invest in understanding flow conditions in fuel beds because this behavior
dominates over the chemical kinetics of combustion for predicting HRR which is
an important parameter in fire modeling.