A Model to Predict Carbon Monoxide of Woods under External Heat Flux – Part I: Theory

Carbon monoxide (CO) is always a significant judgment criterion in fire risk evaluation. Therefore, a model to predict CO of woods under external heat flux was developed in this study. To improve modeling accuracy, fire processes such as water evaporation, volume shrinkage, liquid and gas transport inside wood slab were considered in this model. Three reactions such as water evaporation, oxidation of virgin wood and char were included. For oxidation reactions of virgin wood and char, CO yields of each reaction were considered constant even under various external heat fluxes. This will expand the applications of this model as limited experimental data of CO yields under different external heat flux. Temperature and moisture dependent thermal properties were used for modeling input. Comparisons between experiment and modeling showed that CO production of woods under different external heat flux can be well predicted by this model. This model intends to provide a practical tool to predict toxic gases of combustible materials under fire conditions.This two-part study contains theory, validation and application of a mathematical model. This paper servers as a precursor for Part II: Validation and application of a model to predict CO of woods under external heat flux.