Fire and Heat Transfer Modelling of Small and Large Scale Experiments

Abstract

The present work aims to provide insight on the small- and full-scale models of building construction materials and structures in fire scenarios. Steps are taken toward a long-term goal, which is to develop a complete model for heat and mass transfer across walls and in compartments in case of fire. This is an important aspect of fire safety engineering in which, with the help of in-depth knowledge of the fire on the buildings and construction materials and numerical methods, a complete understanding of fire behaviour can be obtained. Therefore, applications can be used to design safe buildings, analyze fire risks, and develop optimized egress models.

Experimental studies selected for the modelling are conducted at the University of Waterloo Fire Research Lab (UWFRL) for the validation and comparison of the simulation results. OpenFOAM, an open-source C++ toolbox for computational fluid dynamics modelling, is selected for modelling. In the first step, a small-scale heat transfer model presents the thermal prediction of construction materials at high temperatures in cone calorimeter tests. The model predicts the temperature well for two specimens exposed to constant and transient heat flux values. Improvements can be made using accurate thermophysical properties and a thermal contact model between layers of different materials. In the next step, a large-scale fire model is applied to an insulated compartment that is separated from another room by a steel wall, using Firefoam. Besides heat transfer, combustion, chemistry, and turbulence are included in the model. Large Eddy Simulation (LES) for turbulence, Finite Volume Discrete Ordinates Method (fvDOM) model for radiation and Eddy Dissipation Concept (EDC) for chemistry are employed. The model predicts the early stage of fire growth, but underpredicts the temperature during the decay phase. This tool can be used for future work as a first step toward a more sophisticated model for degrading and non-degrading wall assemblies in compartment fires.