Relationships between energy release, fuel mass loss, and trace gas and aerosol emissions during laboratory biomass fires

• Published in: Journal of Geophysical Research: Atmospheres 2008-01, Vol.113 (D1), p.n/a
• Main Authors: Freeborn, Patrick H., Wooster, Martin J., Hao, Wei Min, Ryan, Cecily A., Nordgren, Bryce L., Baker, Stephen P., Ichoku, Charles
• Format: Article
• Language: English
• Subjects: Aerosols; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Biomass; biomass burning; Earth, ocean, space; Emission; Energy consumption; Exact sciences and technology; External geophysics; fire radiative energy; Fires; Fuels; Fundamental and applied biological sciences. Psychology; Mass production; Meteorology; Particles and aerosols; smoke emissions; Synecology; Terrestrial ecosystems
• ISSN: 0148-0227; 2169-897X; 2156-2202; 2169-8996
• DOI: 10.1029/2007JD008679

Forty‐four small‐scale experimental fires were conducted in a combustion chamber to examine the relationship between biomass consumption, smoke production, convective energy release, and middle infrared (MIR) measurements of fire radiative energy (FRE). Fuel bed weights, trace gas and aerosol particle concentrations, stack flow rate and temperature, and concurrent thermal images were collected during laboratory‐controlled burns of vegetative fuels. Using two different MIR thermal imaging systems, measurements of FRE taken at polar angles of ∠48° and ∠60° were found not to be significantly different from each other (p < 0.05), but were significantly different from those obtained at ∠76°. A simple linear regression revealed that less than 12% of the variation in biomass consumption remained unexplained by the measured FRE regardless of MIR sensor characteristics, fuel type, or viewing angle. Measurements of FRE detected per unit of dry organic material consumed ranged from 1.29 to 4.18 MJ/kg, corresponding to an average of 12 ± 3% of the higher heating value of the biomass. Whole‐fire emission factors agreed with previously reported values, and emission ratios relating total mass production to FRE were determined for CO2, CO, NO, NO2, and particulate matter less than 2.5 μm in aerodynamic diameter. A heat balance performed on the system showed that the release of convective energy could be predicted from a measurement of FRE (r2 ≥ 0.84), and together these two modes of heat transfer accounted for 61 ± 13% of the total, potential heat of combustion available in the preburn solid fuel.