Dissolution Characteristics of Mixed Insulating Oils for Transformers Based on Density Functional Theory

One can anticipate enhancements in the performance limitations of an individual insulating oil by blending mineral and vegetable insulating oils using precise techniques and proportions, resulting in the creation of hybrid insulating oils. Because of variances in both the components and molecular arrangements found in mineral and vegetable insulating oils, as well as the existence of interaction forces between them, the solubility characteristics will therefore be affected. In this study, based on density functional theory, to explore the structural attributes of hydrocarbon molecules in mineral oil and triglyceride molecules, we utilized molecular fragment analysis as well as electrostatic potential surface examination. The results show that the two molecular fragment orbitals in the triglyceride-hydrocarbon system contribute to the dimer molecular orbitals, in which the aromatic hydrocarbon-trilinolein (C
20
H
26
-C
57
H
98
O
6
) system has a binding energy of −0.11 kcal/mol and the mutual attraction is the most significant among the selected several triglyceride-hydrocarbon systems significant. Furthermore, in the four major triglycerides chains found in palm oil, the carbon-carbon double bond (C=C) and oxygen atoms in the ester group (-COOR) exhibit partially negative electrostatic potential, which interacts attractively with the predominantly positive electrostatic potential in mineral oil hydrocarbon molecules, resulting in strong intermolecular forces. These forces facilitate the dissolution of triglycerides in mineral oil. The study findings not only offer insights into the dissolution properties of blended dielectric insulating liquids but also serve as a theoretical foundation and provide data support for the advancement and refinement of mixed insulating oils in transformers.