Ignition and Combustion of Single Wood Spheres Heated in High Temperature Air Streams
Date Issued
2004
Date
2004
Author(s)
Hsi, Chih-Lun
DOI
en-US
Abstract
The ignition and combustion behavior of single wood spheres heated in high temperature air streams was investigated by experiments. Three species of wood were used for experiment in this work. The single wood spheres were oven-dried and exposed to various temperature and flow rate of air streams. Wood grain orientation was specifically kept perpendicular or parallel to the air stream. Some tests for measuring the variations of wood sphere internal temperatures were conducted by thermocouples imbedded in the wood spheres. It was observed that the ignition time is independent on air flow rates or grain orientation at 873 K. Glowing reaction was observed prior to ignition for wood heated at 773 K, and directly flaming ignition for 873 K. A correlation for estimating the time required to flaming ignition was proposed. A simple model considering the heats of pyrolysis and moisture evaporation was used to predict the mass and temperature histories prior to flaming ignition. Elemental composition analysis shows that the atomic ratio of H and O of the internal material of burning wood spheres are essentially within a close range during flaming combustion. Shrinking core model was used for estimating the burning rate of wood spheres. Char combustion rate was also discussed in this study.
Subjects
起燃
木材
熱解
燃燒
pyrolysis
wood
combustion
ignition
Type
thesis
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