Nanoscale Insights Into Insulating Oil Emulsification: Dynamic Interplay of Temperature and Water Dynamics

Abstract

To ensure the safe and efficient operation of electrical equipment, it is essential to study the microdynamic mechanisms and thermodynamic characteristics of the insulating oil emulsification process at the nanoscale. In this work, the behavior of water in insulating oil under various temperatures was visualized through a dynamic oil–water model using molecular dynamics (MD) simulations and in situ observation. Quantitative analysis revealed temperature’s influence on water droplet dynamics, exposing key details in nucleation and growth. The research findings indicate that the electrostatic shielding effect is critical in the nucleation process, and strong hydrogen bonding among water molecules promotes stable aggregate formation. Higher temperatures decrease the electrostatic shielding by the oil–water mixture and reduce molecular orderliness, decrease distances, and promote molecular collisions and nucleation. Furthermore, under sustained supersaturation, higher temperatures accelerate water molecules motion, boosting free water growth and facilitating the transition of water molecules from a free state to a dissolved state. The magnitude of nucleation rate was generally on the order of 1035 ${\mathrm {m}}^{-{3}}\cdot {\mathrm {s}}^{-{1}}$ and the growth rate was 0.3–1.8 ${\mathrm {m}}\cdot~{\mathrm {s}}^{-{1}}$ in the simulated parameters range. These findings aid in understanding water issues in electrical equipment, improving design and operation for enhanced reliability and efficiency.