- Author
- Frandsen, W. H.
- Title
- Smoldering Duff: Limits, Heat Evolved, and Burn Rate.
- Coporate
- Montana Univ., Missoula
- Report
- Thesis, 1989, 156 p.
- Distribution
- AVAILABLE FROM UMI Dissertation Services, A Bell & Howell Company, 300 North Zeeb Road, P.O. Box 1346, Ann Arbor, Michigan 48106-1346. Telephone: 1-800-521-0600 or 734-761-4700. Website: http:www.umi.com
- Keywords
- smoldering | burning rate | soil temperatures | decomposition | moisture | forestry | forest fires | oxygen consumption | combustion | ground fires
- Identifiers
- smoldering Canadian sphagnum peat; influence of moisture and mineral soil on the combustion limits of smoldering forest duff; heat evolved during smoldering; burning rate of smoldering peat; measurement of smoldering heat by oxygen consumption
- Abstract
- Smoldering ground fires can raise mineral soil temperatures above 300 C for up to 12 hours with peak temperatures near 600 C. Such temperatures result in decomposition of organic material and death of important soil organisms. Smoldering is difficult to detect and continues long after the main fire front has passed. Three facrors that describe smoldering uere investigated. They are the sustainable limits, the heat evolved within those limits, and the rate of burning. Each factor was examined for its dependence on the moisture and inorganic content expressed as mass ratios relative to the organic mass: RM for the moisture ratio and RI for the inorganic ratio. Canadian sphagum peat was used as the fuel for all studies. The organic bulk density was fixed at 110 kg m-3 for the limit study. Smoldering is sustained if the quantity Rm+RI/4 is Iess than 1.1. The heat evolved is derived from the heat of combustion and was investigated by monitoring the mass of oxygen consumed during smoldering. Sample organic bulk densities were comparable to the field and ranged from 90 to 180 kg m-3. Moisture ratios ranged from 0 to 0.8 and inorganic ratios from near zero (natural peat inorganic ratio) to 4.0. Results were normalized to the original organic mass. There is no dependence of the heat content on organic bulk density of the inorganic ratio, and very little change with the moisture ratio. The average value for all observations (N=I90) was 14.79 MJ kg-1 with an error less than 4.5%. The time to consume the organic mass was monitored along with oxygen consumption. The average burning rate, BR, is independent of the organic bulk density.