NUMERICAL STUDY ON THE INFLUENCE OF INDEPTH RADIATION IN THE PYROLYSIS OF MEDIUM DENSITY FIBREBOARD

摘要

In order to accurately predict the flame spread along a combustible wall, a better understanding of the burning behaviour of a material exposed to external radiation is required. This work focuses on simulating the pyrolysis behaviour of the Medium Density Fiberboard (MDF) material. The numerical simulation tool used in this study is the Fire Dynamics Simulator (FDS 6.2.0). A one-dimensional heat transfer solver that includes in-depth radiation is employed. The simulation results were compared with the experimental data, including the mass loss rate, and the surface temperature. The base case does not show satisfactory results for the time to reach the first peak and the value of that peak in the mass loss rate curve when compared to experimental data. The influence of the material properties and model parameters on the pyrolysis behaviour of MDF has been investigated in detail through a sensitivity analysis. For the considered range of parameters, the most significant influence on the time to the first peak comes from the emissivity, followed by the thermal conductivity, specific heat, and moisture content. For the peak mass loss rate, the most significant influence comes from the absorption coefficient, followed by the through-thickness density, the moisture content, and the specific heat. Only when proper values of these parameters were employed in the simulation, the onset of the pyrolysis process can be reasonably predicted. Through a simple trial and error procedure, a set of 'optimized' values of parameters including the in-depth absorption coefficient of char was obtained, which results in better agreement with experimental data.