Numerical Study of the Effect of Nanoparticle Shape on the Thermal Conductivity of Mineral Oil-Based Nanofluids Used in Power Transformers

Searching for solutions to increase the dielectric strength and thermal conductivity of insulating oils used in power transformers is important to improve the efficiency of these devices Nanofluids (NFs) are considered among the promising alternatives for use in insulation systems for high voltage applications due to their efficiency in terms of improving thermoelectric properties compared to traditional dielectric oils. The present study is a numerical modeling of the thermal performance of dielectric nanofluids using the finite element method based on the COMSOL Multiphysics software, by developing a three-dimensional model to evaluate the thermal conductivity of NFs and to highlight the role of nanoparticle (NPs) shape in influencing the thermal conductivity efficiency of mineral oils (MO) used in power transformers, titanium oxide nanoparticles $\left(\mathrm{TiO}_{2}\right)$ were used in different shapes (Spheres, Bricks, Cylinders, Platelet) and fixed volume concentration (2.8 vol. %). The results showed a noticeable improvement in the thermal conductivity values of the dielectric fluid when adding NPs, and the shape of the particles had an effective role in increasing thermal performance. NFs based on platelet-shaped NPs provided the best results in terms of thermal transfer efficiency, followed respectively by cylindrical, brick, and spherical nanoparticles.