Numerical Study on Natural Convective Heat Transfer of Nanofluids in Disc-Type Transformer Windings

Nanofluid is an innovative approach to improve the thermal conductivity of fluid by adding nanoparticles. Transformer oil-based nanofluids have been prepared and measured, which verifies the concept and demonstrates the potential in oil-immersed power transformer applications. In this paper, the effect that nanofluids (oil/SiC) have on the natural convective heat transfer in disc-type transformer windings is investigated numerically. The multi-phase mixture model is employed for the first time to analyze such a nanofluid flow field, and the single-phase model is also used for comparison and mutual authentication. After using the nanofluid, significant temperature drops inside the windings are observed, and in some cases, the heat transfer performance is further improved by the adjusted mass flow rate distribution. The impact of nanofluids is enhanced with the rising volume fraction of nanoparticles. Before performing the study, the numerical model is validated using the existing results of the referenced windings cooled by transformer oil.