ABSTRACT The scope of this work concerns the determination of kinetic parameters of the thermal oxidative degradation of Mediterranean scrubs concerned by wildland fires. Oxidative reactions are monitored thanks to Differential Scanning Calorimetry and ThermoGravimetric Analysis allowing heat flux and mass loss recordings. Two dominating over-lapped exothermic reactions are observed. We propose a method to individualize experimentally the reactions. The enthalpy variation of each exothermic phenomenon is obtained in this first stage. In a second time, a Model Free Method is applied on each isolated curve to determine the apparent activation energies vs. the conversion degree. The values of activation energies clearly confirm the existence of two different reactions. According to these results, a global reactional kinetic scheme is proposed, it is composed of two independent and consecutive reactions. In fine, mean values of enthalpy variation and apparent activation energy previously determined are injected in a Model Fitting Method to obtain the reaction order and the preexponential factor of each oxidative reaction. Simulations obtained with the calculated thermo-kinetic parameters match correctly the experimental data.
Buy this Article
|