Under-ventilated Compartment Fires: A Full-Scale Test with Wood Pallets

Under-ventilated enclosed fires are recognized to be important scenarios, which can bring important potential risks. These phenomena occur with different ventilation conditions (natural or mechanical), providing insufficient oxygen concentration and over production of unburnt gases in the fire zone. A fullscale test has been performed using wood pallet fire. The test rig is built with marine containers. The fire occurs in a room and the smoke spreads in two other compartments. The experimental set-up provides source mass loss rate, temperatures close to the fire and in the smoke flows. Fire growth and smoke spread are detailed and analyzed. It is shown that, after an ignition period, oxygen depletion is strong in the fire room and an under-ventilated combustion occurs, and the temperatures begin to increase continuously everywhere in the compartments and in the smoke plume at the exit. CFD modeling of the fire growth has been performed by specifying the kinetic of the heat release rate (HRR) or with a simplified pyrolysis mechanism with one step. The sequence of the events, which have been observed inside the compartments during the test, is well reproduced within the CFD results. However, the comparison between calculated and observed temperatures highlights the difficulties to calculate the accurate heat release rate (HRR), its kinetic of growth and the maximum value, when the fire is in the under-ventilated regime.