Thermal stability and insulation characteristics of three-phase fire-fighting foam exposed to radiant heating

Abstract

The limited stability and heat insulation performance of the traditional aqueous film forming foam (AFFF) affects its efficiency in fire extinguishing. Recently, functional nanoparticles have been used as stabilizers. The formed three-phase foam exhibits better performance. However, the mechanisms and heat transfer behaviors of the three-phase foam are still unclear and require further clarification. Therefore, in this study, the thermal stability, the volume expansion, and the temperature profiles inside the foam layer exposed to the high-temperature environment are studied. The results indicate that the high ambient temperature benefits the foaming but reduces the foam stability. The foam layer exposed to continuous radiant heating presents three successive stages, i.e. the initial stage, the balanced stage, and the collapse stage due to distinct heat transfer characteristics in the depth direction. Moreover, the effects of foam composition and operation conditions on foam insulation are further evaluated. It is found that the insulation performance of foam can be enhanced with higher particle concentration, especially hydrophobic particles. High foam expansion ratio leads to better foam stability but worse thermal insulation. The life of foam decreases with the radiation heat flux. The results provide useful guidance for achieving high fire-extinguishing efficiency of foam.