Pinus pinea emissions and combustion characteristics of limonene potentially involved in accelerating forest fires

It has been reported in the literature that under some conditions forest fires with normal behaviour suddenly start to propagate at unusual and very fast rate of spread. A possible explanation of these accelerating forest fires, based on the ignition of a Volatile Organic Compounds (VOCs) cloud, has been discussed in the literature. Most of vegetal species when heated emit volatile substances. We have shown using a flash pyrolysis apparatus that a typical Mediterranean species, Pinus pinea, emits fourteen components, mainly limonene. P. pinea needles are preheated between 373 and 473 K and the maximum emission is found at 433 K. Combustion characteristics, namely laminar burning speeds, Markstein lengths and flame thicknesses of limonene/air premixed flames are determined using the spherical expanding flames method coupled to a nonlinear methodology. Experiments are performed in a spherical combustion chamber at atmospheric pressure and at elevated temperatures. An empirical correlation is developed to calculate the laminar burning speeds as a function of equivalence ratio and temperature. Experimental results of limonene are compared to the computed values of JP-10 and n-decane.

► VOCs emissions of Pinus pinea are measured at elevated temperatures. ► Combustion characteristics of limonene/air mixtures are determined for different preheat temperatures. ► Numerical simulations of laminar burning speeds of JP-10 and n-decane are performed. ► The combustion characteristics will be used to investigate the thermochemical approach for accelerating forest fires.