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Leaking-burning coupling fires caused by oil leakage from tanks cause significant damage to occupants and the equipment. A series of experiments was conducted to investigate the fire behavior of a tank with oil leaking and burning. The tank released n-heptane into the tray below, forming a fire that heated the tank. The tray size and leak diameter varied. Spill fires, steady pool fires, boiling pool fires, and jet fires were observed. The results show that within a specific leak diameter range (2.5–3.5 mm), the maximum pressure increased with decreasing leak diameter. The fuel vapor spread along the bottom of the tank, causing the expansion of the flame. Consequently, the pool fire size was larger than the actual tray size, thereby making the maximum pressure and thermal radiation almost independent of tray size. When the leaking oil began to boil and burn, the pressure increased rapidly and the emitted radiative heat flux was the largest; therefore, fire posed the most serious threat. A computational fluid dynamics (CFD) modeling approach was employed to predict the time when the temperature of the leaking oil reached its boiling point. The predicted results were validated against the experimental ones, which provided useful support for emergency response plans. [ABSTRACT FROM AUTHOR]

Most of the current research on heavy gas dispersion focuses on how fixed obstacles affect gas spreading. The turbulence caused by the movements of people or traffic will significantly affect heavy gas dispersion. Accordingly, this study presents an investigation of heavy gas dispersion under the influence of moving obstacles, which is based on the dynamic mesh approach using computational fluid dynamics (CFD). A turbulence model suitable for such a condition has been developed, and we have designed a small-scale experiment to verify the model's viability. Consequently, the verified model is further applied to a full-scale scenario for a chemical factory where a chlorine leak triggers an evacuation movement. On the basis of this scenario, we simplify the massive escape crowd to a regular geometric model, and the effects of the speed and size of movable obstacles on gas dispersion have been investigated by means of the RNG k-ε model and the layering updating approach in the dynamic mesh. [Display omitted] [ABSTRACT FROM AUTHOR]

The prediction of the fire hazard of a tank during burning of leaking contents is significant during the emergency response to tank fire accidents. A detailed investigation was conducted in small-scale tank fire experiments with different filling levels and tray sizes. The liquid (n-heptane) leaked from the tank and burned in the containment structure (the tray) below, heating the tank and emitting radiative heat flux to the surroundings. The temperature of the leaking contents increased as the heating progressed and eventually reached its boiling point. When the leaking contents boiled and burned, the fire hazard was the greatest because the internal pressure increased rapidly, and the mass burning rate and thermal radiation reached a maximum. Modifying the previous models, this paper proposed a virtual tray modeling approach for predicting the mass burning rate and thermal radiation during the burning of boiling leaking contents. The maximum relative error between measurement and prediction was approximately 20%, indicating the availability of the modified models. A three-dimensional transient simulation was set up using the computational fluid dynamics (CFD) technique to predict the temperature response of the leaking contents, and thus, the elapsed time before boiling and burning of the contents was well predicted. These results can provide scientific support for emergency response teams to control similar tank fire accidents. [ABSTRACT FROM AUTHOR]