Bubble Motion and Insulation Characteristics of Evaporative Cooling Medium C6F12O

Abstract

Perfluorohexanone (C₆F₁₂O) has emerged as an ideal medium for electrical equipment evaporative cooling systems due to its excellent comprehensive properties, including low boiling point and superior insulation performance. The heat dissipation capacity and insulation characteristics of the system can be significantly affected by the bubble dynamics of the medium during the evaporative cooling process, thereby limiting its application in high-voltage, high-capacity power equipment. Therefore, the investigation of the bubble behavior and insulation properties of C₆F₁₂O is considered crucial for practical applications in power equipment. In this study, comprehensive investigations are conducted to examine the effects of temperature, electric field, heat flux density, and electrode spacing on bubble dynamics and insulation characteristics using C₆F₁₂O. The experimental results reveal that bubbles exhibit five distinct behavioral modes in the absence of the electric field: migration, deformation, fusion, splitting, and fragmentation. The system is identified to operate in natural convection regime at 305–315 K and nucleate boiling regime at 322–348 K. Under uniform electric fields, the breakdown characteristics of two-phase flow are found to resemble those of liquid phase due to the “liquid lock” phenomenon. When the heat flux density ranges from 0 to 3.31 W/cm², the two-phase system preserves its liquid-phase properties and adheres to a two-parameter Weibull distribution due to the liquid lock effect. As the heat flux density increases to 4.41–5.51 W/cm², bubbles eventually penetrate the liquid lock barrier, establishing gas-phase conduction pathways. These findings provide valuable theoretical guidance and practical References for the engineering application of evaporative cooling in electrical power equipment.