Numerical prediction of mass loss rate of expanded polystyrene (EPS) used for external thermal insulation composite systems (ETICS) in cone calorimeter

摘要

External thermal insulation composite systems (ETICS) consisting of insulation core and decorative surface materials are quite common in new construction and refurbishment buildings. Expanded polystyrene (EPS) ETICS are widely used. EPS ETICS consist of 3 distinct layers of varying composition and physical structure. The mass loss rate (MLR) and heat release rate play an important role in the evaluation of material reaction-to-fire performance. In the study described in this paper, 2 different numerical simulation tools, Fire Dynamic Simulator (FDS 6.5) and ThermaKin2D, were investigated with respect to their capability to predict the MLR of EPS ETICS products exposed to different fire conditions. The materials were characterised in order to provide suitable input parameters for the models. With accurate input parameters, the mean error between the predicted curve and the experimental MLR curve was calculated as approximately 16% for heat fluxes 30 and 50 kW/m~2. The discrepancies between predicted and measured results are ascribed to the flame flux, which is not well modelled. It is found that the flame flux accounts for 15% of external heat flux in FDS 6.5 and for 18.0% of external heat flux in ThermaKin2D.