Experimental Study on the Thermal Conductivity and Viscosity of a Transformer Oil-based Nanofluid Containing ZnO Nanoparticles

This study investigates the effect of ZnO nanoparticles of the transformer oil on thermal conductivity and dynamic viscosity characteristics. For this purpose, the consequence of temperature and nanofluid concentration variations as important parameters affecting thermal conductivity and viscosity of the samples, have been explored. The results indicated that the thermal conductivity of the nanofluid was higher than that of the pure transformer oil at the temperature of 25°C. Also, a rise in the concentration of the nanoparticles of the transformer oil increased the thermal conductivity of the nanofluid. Besides, the thermal conductivity at the volume fractions of 0.05% and 1% increased by approximately 4.61% and 11.53%, respectively. The dynamic viscosity reached the highest level at maximum volume fraction in all temperatures. In addition, an increase in the temperature reduced the dynamic viscosity of both the pure transformer oil and the nano-oil. At a given temperature, a rise in the volume fraction of ZnO nanoparticles enhanced the dynamic viscosity. Moreover, to predict the dynamic viscosity of the nanofluid, a new correlation was presented as a function of temperature and volume fraction with R-Sq=0.9913.