Modelling bench-scale fire on engineered wood: Effects of transient flame and physicochemical properties

Abstract

The engineered wood such as medium density fibreboard (MDF) has been widely used in buildings and constructions, and has the advantages of energy saving, consistent performance, and fine finish. However, its fire hazards have not yet been well studied. In this paper, a one-dimensional pyrolysis model was proposed for fires on the bench-scale MDF sample, and considered four features: (I) four-step non-first-order kinetic model, (II) transient flame heat flux, (III) heterogeneous vertical density profile, and (IV) sample shrinkage. The default modelling scheme including all four features gave excellent agreements with the experimental ignition delay time and mass loss rate of MDF under constant cone irradiations of 35–65 kW/m2. Comparisons showed that assuming one-step kinetics and homogeneous vertical density profile can clearly affect the prediction of ignition delay time. Neglecting the sample shrinkage can significantly impair the prediction of mass loss rate. If multiple simplifications were used together or in different sequences, synergy and compensation effects were discovered in modelling. It is suggested that the influence of these four features as well as their compensation and synergy effects should not be overlooked in modelling fires on engineered wood, even for a bench-scale fire.