Study on Compatibility of Vegetable Insulating Oils and Mineral Insulating Oils for Transformer Based on Molecular Simulation Methods

Traditional mineral insulating oils have problems such as environmental pollution and low fire resistance. Vegetable insulating oils are prepared from vegetable oils through refining and modification processes and have high fire resistance and renewability. However, vegetable insulating oils have high viscosity and poor heat dissipation performance. Hybrid insulating oils can complement single insulating oils by mixing mineral and vegetable insulating oils. This paper investigates the compatibility between palm oil and mineral oil. COSMO calculations of triglyceride and mineral oil alkane molecules were performed using molecular simulations and the COSMO-RS model. We have carried out separate calculations of the molecular surface charge densities (σ-spectra) for four major triglycerides within the palm oil as well as for three major carbon 20 alkane molecules within the naphthenic mineral oil. We illustrate the polarity relationship between the glyceride molecules and alkane molecules of mineral oils and derive the principle of similar intercalation of the glyceride molecules with the alkane molecules of mineral oils from the microscopic point of view of the molecules. The findings suggest that palm oil and the mineral oil possess comparable forces between the molecules, which allows for stable blending.