On the Boiling Mechanism of an Oil-in-Water Emulsion

This paper presents the experimental results for heat transfer during boiling under natural convection conditions of an oil-in-water emulsion on the surface of a wire heater 0.10 mm in diameter. The studies were carried out with an emulsion of an organic silicon liquid (silicone oil) PES-5-water at an oil concentration of 0.5 to 5.0 wt %. The process of nucleate boiling of water and the PES-5 oil-water emulsion is visualized by high-speed video recording. In the emulsion, water is involved in nucleation, and oil droplets interact both with the heating surface and vapor bubbles. Oil droplets suppress potential boiling centers for water due to good wetting of the heating surface, which increases the initial boiling point of the emulsion. The wettability and low thermal conductivity of the oil also harm the local characteristics of heat transfer during the nucleate boiling of the emulsion.