Thermal combustion and oxygen chemisorption of wood exposed to low temperature long term heating

Abstract

This research studied the combustion of wood exposed to low-temperature for an extended duration. The role of moisture was investigated using a revised analytical heat conduction model. The results showed that the allowance of moisture effects through the use of moisture-mediated thermophysical terms were not sufficient to capture the spontaneous ignition mechanism of green wood. Two low-temperature heating models were developed. For the initial drying phase (IDP) model, evaporation was modeled as a boundary condition for initial drying. As heating continues above 100B0C, and internal evaporation term was re-introduced for extended drying phase (EDP) model. The numerical solution illustrated the importance of the interaction of moisture flows and temperature development for self-heating. Chemisorption was examined for nitrogen-heated and air-preheated wood chars exposed to 140B0C and 150B0C up to 50 days. Fourier-transform Infra-red Spectroscopy (FTIR) showed that as the formation of C=O groups stabilised the wood chars, pyrophoric wood chars would only be formed when pre-exposed to temperature lower than 200B0C.