The Role of Moisture on Combustion of Pyrolysis Gases in Wildland Fires

Abstract

The role of water vapor, originated from the moisture content in vegetation, on the combustion process was investigated via simulating an opposed diffusion flame and a laminar premixed flame with pyrolysis gases as the fuel and air as the oxidizer. The fuel was mixed with water vapor, and the simulation was repeated for various water mole fractions. In both of the diffusion and premixed flames, the smaller the water mole fraction, the higher the maximum temperature. No reactions occurred when the water mole fraction was 0.65 or larger in the diffusion flame, and 0.70 or larger in the premixed flame. The maximum energy release rate and the flame speed decreased with the increase of the water mole fraction in the premixed flame. In both flames, O₂ and H were the components that showed dramatic changes with the change of the water mole fraction.

Keywords:

• Pyrolysis
• Wildland fire

ACKNOWLEDGMENT

The authors gratefully acknowledge financial support from the USDA Forest Service PSW Research Station through cooperative agreement 10-JV-11272166-091 awarded to the University of Alabama in Huntsville.

Notes

¹The use of trade names is presented for informational purposes only and does not constitute endorsement by the U.S. Department of Agriculture.

Note: Skeletal mechanism is by Zhou and Mahalingam (2001) with updated values of parameters available in most recent version of CHEMKIN-Pro.

M is used in the above reactions as a placeholder for multiple chemical species (CHEMKIN-Pro, 2008).