Fire Safety Science Digital Archive

The burning of a thin fuel-layer floating on water is a problem of interest in unwanted fires. Heat losses to the water below may cause its boiling and induce an eruptive vaporization of explosive and violent character referred to as thin-layer boilover. A few years ago the present authors began a systematic and comprehensive study of this complex phenomenon. The results emphasized the importance of heat transfer in the direction normal to the fuel and sublayer surfaces. They corroborated that boilover is due to the heterogeneous boiling nucleation at the fuel/water interface, in sublayer water that has been superheated. A wide range of boiling points fuels were tested including a crude-oil, heating oil, and five single-component fuels. Some of the parameters of the process were varied to observe their effect on the boilover characteristics and, through them; some of the controlling mechanisms were inferred. The influence of the major parameters of the problem, specifically the initial fuel-layer thickness, the pool diameter, and fuel boiling point, on the temperature history of the fuel and water and time to the start of boilover, was studied. A simple, one dimensional, quasi-steady, heat conduction model helps to understand how these different problem parameters affect boilover. However due to its limitations, there was a need to develop a more elaborated model, unsteady and including in-depth radiation absorption.