Thermal responses of a concrete slab under hydrogen fuel cell vehicle fires in a semi-open car park

This work aims to investigate the thermal behaviors of the concrete ceiling slab of a semi-open car park exposed to localized fire in hydrogen fuel cell vehicles. For this purpose, a numerical simulation of the hydrogen fuel cell vehicle fire was performed in the Fluid Dynamic Simulator and then coupled with a subsequent thermal analysis of concrete structure carried out in ANSYS Mechanical APDL. In particular, an automatic procedure was used to extract the output of the fire simulation and apply them as boundary conditions of the thermal model. The one-way coupling procedure involving fire simulation and transient thermal analysis has been validated by comparing it with concrete temperatures of a previous test study. Then, two parameters, the diameter of thermal pressure relief devices (1 mm, 2 mm, 3 mm, and 4 mm) and fire spread time between vehicles (0 min, 20 min, and 30 min), are taken into account to study the thermal properties of concrete. The analysis revealed that an increase in the nozzle diameter of the thermal pressure relief device leads to a rise in the maximum concrete surface temperature. The simulation results also showed that the maximum value of the heat release rate increases with a higher value of the nozzle diameter of the thermal pressure relief device and a shorter fire spread time between vehicles.