Wind tunnel modeling of atmospheric emissions from agricultural burning: influence of operating configuration on flame structure and particle emission factor for a spreading-type fire

Agricultural burning is a significant source of atmospheric pollutants throughout the world and has lately been subject to increased regulation in North America and Europe. A combustion wind tunnel having multiple operating configurations was developed to simulate field burning conditions and to provide direct measurement of emission factors. Sensitivity to operating configuration was determined for total suspended particulate matter (TSP) emissions and flame structure. TSP emission factor varied from 0.505 to 0.727 % of fuel mass as a result of controlled changes to the inlet flow velocity and turbulence characteristics and to ventilation through the fuel bed. Flame structure was examined through measurements of local temperatures, gas concentrations, and soot volume, the latter obtained by laser-light extinction. Although the range in TSP emission factor was not large, wind speed appeared to be the dominant parameter affecting the emission of particles. Results of this study will be used to determine operating protocols for future tests investigating criteria and toxic emissions from agricultural burning.