Effects of BN nanoparticles on thermal conductivity and breakdown strength of vegetable oil

Vegetable oil is based on natural ester oil, which is considered as the alternate natural source of traditional mineral insulating oil in electrical transformers. The oil applied in transformers performs dual functions of insulating and cooling materials. The purpose of this paper is to obtain a new type of nano-modified vegetable oil with both improved dielectric and thermal properties. Boron nitride (BN) nanoparticles with high thermal conductivity were dispersed into vegetable oil to form the nanooil. Thermal and dielectric properties of the samples before and after modification were measured. Temperature change and heat distribution of the samples in heating process were measured by a temperature sensor and an infrared thermal imager. Dielectric property experiments were performed in accordance with IEC standard. Relative permittivity, dissipation factor and electrical conductivity tests of the nanooil were conducted along with ac and dc breakdown strength in a range of temperature. It is found that the nanooil shows improved thermal and dielectric property compared with non-modified oil. Obtained results exhibit significant improvement in heat transfer process with increasing the concentration of BN nanoparticles.