Pyrolysis-Based Fire Modeling of Polyurethane Foam Incorporating a Grid-Independent Method

Abstract To apply pyrolysis-based fire modeling to fire risk assessment, problems associated with coarse grids, such as inaccurate predictions of ignition and fire spread, must be addressed. Polyurethane foam (PUF) is widely used as an insulating material, and its constituent components are well characterized, making it suitable for pyrolysis-based fire modeling. In this study, a PUF fire model was developed using a pyrolysis model incorporating a grid-independent modeling method. PUF was represented by three components: virgin polyurethane foam, polyol beads, and a polyol layer. The combustion characteristics were adjusted by varying the area exposed to gas-phase cells and validated against cone calorimeter experiments. The proposed PUF fire model smoothly reproduced the two-stage combustion behavior, although the peak heat release rate during the second stage was overpredicted, particularly at low external radiative heat fluxes. Based on the validated PUF fire model, the grid-independent method was applied to PUF slab fire simulations. The method adjusted thermal properties and reaction kinetic parameters according to the cell temperature, which varied with grid size, while maintaining the one-dimensional heat transfer solution. The proposed method successfully reproduced the HRR and fire spread rate of the PUF slab fire, although a time delay in fire development was observed.