Experimental and numerical investigations on the use of liquid nitrogen streams to suppress alcohol pool fires

Liquid nitrogen (LN 2 ), a widely used cryogen, is proposed as an effective and environmentally benign fire suppression agent when tackling challenging fires, such as liquid hydrocarbon pool fires. Laboratory-scale experiments using liquid nitrogen were conducted to extinguish small alcohol pool fires (D = 20 cm). The axial temperature profile over the fuel surface and the mass history of the pool during the fire extinction were recorded and analyzed. The minimum quantity of LN 2 required for fire extinction was experimentally determined. A physics-based numerical model was developed using the ADREA-HF CFD code to simulate interactions between the cryogen, the flame envelope and the alcohol pool. Axial flame temperatures, oxygen concentrations and liquid nitrogen mass fractions were predicted numerically before and after the application of the cryogen. Modelling predictions for the liquid jet touchdown time, the amount of liquid mass reaching the ground and the ensuing fire extinction timeframes were in line with experimental observations. The purpose of this model is to predict the minimum amount of this cryogen required for effective pool fire suppression. Such a tool may be used to optimize the application of LN 2 for extinction of accidental fires of fuel spilled or spread on the ground.