Fire Safety Science Digital Archive

This study is part of a larger project which aims at studying the re-ignition behaviour of charring solid fuels under fire conditions. The main objective of this part of the work was to investigate the role of material porosity on the re-ignition characteristics of the fuel. For this purpose, experiments were carried out on a set of surrogate ceramic samples to de-couple the pyrolysis and combustion processes from those associated with heat transfer. The surrogate samples were made out of magnesia silica ceramic with porosity levels of 72.9%, 53.5%, and 35%. Experiments were conducted in a modified cone calorimeter over a range of heat fluxes between 40 to 60 kW/m². The re-ignition delay was found to be significantly affected by the material porosity. The higher the porosity, the longer the re-ignition delay time. For samples having the same porosity level, the re-ignition delay time was primarily a function of sample thickness and the external heat flux. Thicker samples generally showed shorter re-ignition delays. The results of this study will be used in future work to quantify the impact of porosity on the re-ignition behaviour of real samples.