Optical and Infrared Study of the Effect of a High Electric Field on the Pool Boiling Behavior of a Sub-Cooled Dielectric Liquid

The formation and departure of bubbles on hot surfaces is of fundamental significance in many engineering applications including in boiling heat transfer. Both the bubble growth behavior and the boiling heat transfer performance parameters are affected by different variables and conditions, an interesting one of which is the electric field. Understanding its effect is of considerable significance, as it has been observed experimentally that the application of an electric field can lead to a significant enhancement in the boiling critical heat flux of a dielectric fluid. Although the exact physical mechanism behind this effect is not well understood, we hypothesize that it could be correlated to the effect of the electric field on individual evaporating bubbles and their altered interactions with the boiling surface. In this study, we employ optical and infrared imaging techniques to experimentally illustrate the effect of an applied electric field on the behavior of bubbles in sub-cooled pool boiling of a dielectric liquid (HFE-7100). Results indicate that bubble nucleation behavior, bubble geometry, and the bubble three-phase contact line dynamics are all simultaneously affected by the electric field. To help explain the experimental results, we further implement a CFD numerical model of an individual vapor bubble in the presence of an applied electric field.