Flammability limits of biogenic volatile organic compounds emitted by fire-heated vegetation (Rosmarinus officinalis) and their potential link with accelerating forest fires in canyons: A Froude-scaling approach

Abstract

The accelerating forest fire phenomenon for two real accidents is studied. This phenomenon is investigated using the thermochemical hypothesis, based on the ignition of a biogenic volatile organic compounds cloud accumulated in canyons. By heating a Rosmarinus officinalis plant in a specific hermetic enclosure, a mixture of 14 biogenic volatile organic compounds is identified and their mass fractions determined as temperature functions. The theoretical flammability limits of those components are calculated by means of empirical correlations. Froude-scaling law is applied to laboratory emission results to find the concentrations of biogenic volatile organic compounds at field scale. The comparison of the flammability limits with the calculated concentrations at real scale using this changing-scale analysis shows that the emitted biogenic volatile organic compounds can lead to an accelerating forest fire.

Relevance of terpenoids on flammability of Mediterranean species: an experimental approach at a low radiant heat flux

“…The bench-scale flammability experiments offer a limited insight on wildfire behaviour (Fernandes & Cruz 2012). Nevertheless, some modelling approaches based on Froudescaling (Chetehouna et al 2014) suggested that the results of flammability experiments and the implication of BVOCs could be potentially applied in field conditions. In this sense, physics-based models of flammability have the potential to deal with a continuous range of fuel properties and should allow to better understand the impact of fuel dynamics on wildfire spread (Fares et al 2017).…”

“…Contrastingly, more complex physical models like FIRETEC (Linn et al 2002) take into account gaseous-by products of forest fires, but no study has been carried out to assess the influence of terpenoids in fire behaviour using these multiphase models. More recently, the influence of terpenoids in accelerating forest fires has been evidenced at laboratory scale (Chetehouna et al 2009) and modelled at larger scales (Chetehouna et al 2014). Viegas & Simeoni (2010) also hypothesize gas accumulation due to the production of volatile organic compounds as one of the possible causes of eruptive fires.…”

Experimental and numerical investigations of the geometry influence on gas accumulation using a V-shaped forest model

“…Monoterpene LFLs are located around 0.7 %vol (Barboni, 2006;Chetehouna et al, 2014; Catoire & Naudet, 2005) (7.10 -3 ݉ ை ଷ /݉ ௧௧ ଷ ). Therefore, a factor of 3.10 4 is needed to obtain a flammable atmosphere during spring in Valencia (Spain).…”

Contribution of coherent structures to momentum and concentration fluxes over a flat vegetation canopy modelled in a wind tunnel

“…In presence of a fire, the natural emission of volatile organic compounds (VOC) by the vegetation increases due to thermal stress (e.g. Chetehouna et al 2014). Then, the turbulent exchange mechanism between the forest area and the free atmosphere is likely to release highly concentrated gas pockets above the forest where they may find favourable conditions for their ignition.…”