Characterization of Fire Suppression of an Idealized Commodity Using Uniform Water Fluxes

An experimental study was conducted to investigate fire suppression behaviors of an idealized commodity using uniform water fluxes. The objectives of this work are to better understand the physics of sprinkler suppression and to provide validation data for numerical fire modeling. The commodities used in the experiments consisted of corrugated cardboard boxes with a metal liner inside. The cardboard boxes were supported by steel beams to maintain the rack storage geometry similar to the standard commodity where wood pallets supported the cardboard boxes. The uniform water fluxes were generated by a water application apparatus (WAA), and adjusted to achieve uncontrolled and controlled fire scenarios. All fire tests were carried out in rack storage configurations with controlled fuel moisture content to minimize its impact on fire growth. The key measurements included heat release rate (HRR), fuel surface temperature, incident heat flux to the fuel surface and water flow rate transported to the bottom of the fuel array. The test results show that the measured heat release rates under various experimental conditions are very repeatable, and thus are suitable for model validation purposes. The fire test outcomes, i.e., controlled vs. uncontrolled fires, are directly correlated with the amount of water collected during the suppression stage, indicating that the sprinkler suppression mechanism is dominated by water transport in the fuel array. The idealized commodity exhibited fire growth rates similar to the standard commodity, largely due to the impact of the beam support on the fire spread. Furthermore, the critical delivered flux (CDF) that can prevent fire growth is very close between the idealized and the standard commodity. The similarities in fire growth and suppression characteristics suggest that it may be feasible to use the idealized commodity in numerical simulation of fire suppression, as an alternative to the more complex real fuel.