Impact of Subcooled Liquid Jet on the Dynamics of Transition from Steady Film Boiling to Intense Heat Transfer Regime

The properties of the cooled surface and of liquid coolant significantly affect the heat transfer intensity during film boiling and the temperature of transition to the intense regime. As a result, many current studies are devoted to unsteady cooling of vertical cylinders and balls made of various metals with and without coating. The impact of an effectively point source of perturbation (such as, for example, a submerged jet) on the vapor film during film boiling is also of genuine interest. This paper presents experimental results of cooling a stainless steel ball in a liquid when exposed to a submerged jet of the same liquid. The aim of the study is to experimentally measure the surface temperature during the transition from steady film boiling to the intense heat transfer regime of boiling. Different cooling liquids were used in the experiments including water, ethanol, water-ethanol mixtures, and perfluorohexane. It is shown that the transition to the intense mode of heat transfer occurs in aqueous liquids significantly earlier than in liquids with high alcohol content. Despite the influence of the submerged jet, there was no intense heat transfer regime during film boiling in perfluorohexane.