The impact of initial fuel depth on the combustion efficiency of pool fire in an enclosed compartment: A study based on zone model theory

In this paper, the effect of initial fuel depth on the combustion efficiency of pool fires in an enclosed compartment was experimentally studied. Three different sizes of pool fires were conducted in the experiments. Several combustion parameters including burning rate, smoke temperature distribution, and oxygen concentration of pool fires under the different initial fuel depths in closed compartments were obtained. Results showed that the pool fire with the different initial fuel depths would appear in two typical extinction modes: fuel burning out and self-extinction due to lack of oxygen. The whole burning process of the pool fire in the enclosed compartment can be divided into the following five stages: rapid rise stage, transition stage, stable combustion stage, boiling combustion stage, and extinguishing decay stage. The maximum and average values of the burning rate presented the power function of the initial fuel depth. The consumption of oxygen concentration in the compartment was mainly affected by the initial fuel depth, the pool size, and the compartment volume. Dimensionless characterization of the oxygen concentration was adopted to characterize the fire extinction behavior in the enclosed compartment. In addition, on the basis of the combustion process and the extinction behavior, a global combustion efficiency of pool fire was proposed to predict the combustion characteristic while considering the initial fuel depth in the enclosed compartment.