Effect of maghemite nanoparticles on insulation and cooling behaviour of a natural ester used in power transformers

In this paper, an experimental research was conducted to study the effect of the presence of Fe 2 O 3 nanoparticles over cooling and dielectric performance of a natural ester used in power transformers. Different concentration samples of nanofluid have been characterized to find an optimal one, focusing on viscosity, thermal conductivity and dielectric strength. A monitored experimental platform has been used to observe the temperature increases during operation while being cooled. This includes a single-phase distribution transformer, working at three different load levels, C=0.7, C = 1 and C=1.3. Both natural ester base fluid and optimal nanofluid have been used as cooling fluid. At first sight, the nanoparticles seem not to affect neither thermal conductivity nor viscosity at the concentrations used. On the contrary, breakdown voltage of base fluid experiments an enhancement at some of them. The cooling capacity of the nanofluid has also shown an improved behavior.The present investigation has been supported by Spanish Ministry of Economy (DPI2015-71219-C2 1-R), the University of Cantabria and the Government of Cantabria (CVE-2016-6626)