Comparing two methods to measure oxidative pyrolysis gases in a wind tunnel and in prescribed burns

Abstract

Background. Fire models use pyrolysis data from ground samples and environments that differ from wildland conditions. Two analytical methods successfully measured oxidative pyrolysis gases in wind tunnel and field fires: Fourier transform infrared (FTIR) spectroscopy and gas chromatography with flame-ionisation detector (GC-FID). Compositional data require appropriate statistical analysis. Aims. To determine if oxidative pyrolysis gas composition differed between analytical methods and locations (wind tunnel and field). Methods. Oxidative pyrolysis gas sample composition collected in wind tunnel and prescribed fires was determined by FTIR and GC/FID. Proportionality between gases was tested. Analytical method and location effects on composition were tested using permutational multivariate analysis of variance and the Kruskal-Wallis test. Key results. Gases proportional to each other were identified. The FTIR composition differed between locations. The subcomposition of common gases differed between analytical methods but not between locations. Relative amount of the primary fuel gases (CO, CH 4 ) was not significantly affected by location. Conclusions. Composition of trace gases differed between the analytical methods; however, each method yielded a comparable description of the primary fuel gases. Implications. Both FTIR and GC/FID methods can be used to quantify primary pyrolysis fuel gases for physically-based fire models. Importance of the trace gases in combustion models remains to be determined.

IX International Conference on Forest Fire Research and 17th International Wildland Fire Safety Summit: introduction to special issue (Part 1)

“…Based on multi-modal observations of fire behaviour and overlying atmospheric turbulence carried out for four wind-driven experimental fires in gorse shrub vegetation they used novel image velocimetry analysis to outline the dynamics and scales of motion of fire sweeps in relation to overlying atmospheric coherent turbulent structures, the authors present results that are useful for evaluating coupled fire-atmosphere model simulations. Weise et al (2023) compared two methods to measure oxidative pyrolysis gases in a wind tunnel and on small prescribed burns. The authors measured the gas composition by Fourier transform infrared spectroscopy and verified that it differed between wind tunnel and field fires.…”

Quantitative analysis method for the Fourier transform Infrared spectroscopy of gases

“…Fourier transform Infrared (FTIR) spectroscopy is widely used in the quantitative analysis of gases because of its advantages of being fast, sensitive, and non-destructive. Therefore, FTIR gas analysis has become a hot research topic in recent years [5][6][7]. However, affected by the measurement environment, instrumental noise, and spectral complexity, how to accurately extract the concentration information of gases from the captured spectra is a crucial challenge.…”