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Exploring the relationship between non-oxidative bench-scale and oxidative field-scale pyrolysis experiments

David Weise , Thomas Fletcher, Timothy Johnson, WeiMin Hao, Mark Dietenberger, Marko Princevac, Bret Butler, Sara McAllister , Joseph O'Brien, Eva Loudermilk, Roger Ottmar, Andrew Hudak, Akira Kato, Babak Shotorban, Shankar Mahalingam, Tanya Myers, Javier Palarea-Albaladejo, Stephen Baker

Abstract

Background. Fire models often use pyrolysis data from non-oxidizing environments for flaming combustion. Pyrolysis, flaming and smoldering combustion in wildland fires occur in an oxidizing environment. Aims. Determine if composition of pyrolysis gases measured in a non-oxidizing and ambient atmospheric conditions are similar environment using compositional data analysis. Methods. Permanent gases and tars were measured in a fuel-rich environment in a flat flame burner (FFB). Permanent and light hydrocarbon gases were measured for the same fuels heated by fire in ambient atmospheric conditions. Log-ratio balances of CO, CO2, CH4, H2, C6H6O, and other gases were examined by PCA, CDA and PERMANOVA. Key results. Mean compositions changed between the non-oxidizing and ambient atmosphere samples. PCA showed that FFB samples were tightly clustered and distinct from the ambient atmosphere samples. CDA found that the difference between environments was defined by the CO-CO2 log-ratio balance. PERMANOVA and pairwise comparisons found FFB samples differed from the ambient atmosphere samples which did not differ from each other. Conclusion. Relative composition of these pyrolysis gases differed between the oxidizing and non-oxidizing environments. Implications. These results indicate the need for more fundamental research on the early time-dependent pyrolysis of vegetation in the presence of oxygen.

WF23200  Accepted 30 July 2024

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