The self-heating of damp cellulosic materials: I. High thermal conductivity and diffusivity

In this series of papers the effects of moisture content on the self-heating characteristics of stockpiles of cellulosic materials are analysed. The model includes the effects of oxidation, hydrolysis, and the evaporation and condensation of water. In this paper the authors derive the full reaction-diffusion model for the system and then look closely at the case of high thermal conductivity and diffusivity, i.e. the spatially uniform case. Degenerate singularity theory is used to show the model can exhibit at least twenty-five distinct bifurcation diagrams. In particular it is seen that the model can exhibit periodic behaviour (a phenomenon observed experimentally for moist systems), a jump to an intermediate steady state (which could represent smouldering), and a substantial decrease in the critical ambient temperature when moisture content is taken into account.