A steam explosion is the result of the intense heat transfer that can occur when a cold and volatile fluid is brought into contact with a hot fluid. This heat transfer is linked to the fine fragmentation of the hot fluid, so on the explosion timescale, only part of the cold fluid is involved in this heat transfer. In this paper, two different ways of describing this heat transfer are presented. In the first one, i.e., the microinteraction concept, the amount of coolant involved is controlled by the fragmentation kinetics, while in the second one, it is controlled by phase change resulting from interfacial heat balance.