Thermal ignition studies of wood flour

This research study entailed cube basket ignition experiments with wood flour to evaluate experimental constraints on the apparent kinetic parameters obtained from oven tests for use in the Frank-Kamenetskii stationary-state model of thermal ignition. The study was initiated with experiments and analysis of finite, low Biot number effects on the accuracy of apparent kinetic parameters for the stationary-state model. An improved method for correcting the classic model was developed by thoroughly accounting for convection and radiation heat transfer to the basket of wood flour. The apparent activation energy for thermal decomposition of wood flour was found to be 103 kJ/mol.;More recently proposed methods of transient analysis to find apparent kinetic parameters for the Frank-Kamenetskii model called the Crossing Point Temperature method and Heat Release method were applied to the experimental data to determine if kinetic parameters from those approaches were consistent with the Frank-Kamenetskii stationary-state theory. The experimental apparent kinetic parameters from the transient methods of analysis were inconsistent with the Frank-Kamenetskii stationary-state parameters. The transient methods of analysis yielded apparent kinetic parameters that were 20-30 kJ/mol lower than the value determined from the Frank-Kamenetskii model. This offset was consistent with similar studies in the literature, but a different conclusion has been drawn from previous authors who did not directly compare their results to the Frank-Kamenetskii model results. The transient methods are unsuitable for determining apparent kinetic parameters for solid materials that undergo complex decomposition behavior yet still comply with the Frank-Kamenetskii model. It is strongly suggested that these methods not be pursued unless direct comparison and compliance with Frank-Kamenetskii experiments is undertaken.