Investigation of thermal conductivity of semiconducting nanofluid for transformer

Abstract

In the arena of liquid dielectrics, nanotechnology is a positive leap to improve the heat transfer capabilities of an electrical insulating liquid used in transformers. In this study, attention is given to analyze the thermal performance and heat transfer capabilities of nanofluid (NF) made with mineral oil (MO). To prepare NF, semiconducting Zinc Oxide (ZnO) nanoparticles (NPs) are dispersed into the MO which is the base fluid. A concentration of 0.01 by w/v% of ZnO NP are dispersed and two-step procedure is used to prepare the stable NF. The experimental investigation of thermal conductivity is performed by using KD-2 pro (single probe, make Decagon Inc) at room temperature and up to elevated temperature of 75°C. Using COMSOL multiphysics, a thermodynamic model is developed to study the alteration in thermal conductivity and to validate the existing theory about it. A comparative analysis of thermal conductivity for NF and MO are carried out experimentally and theoretically. From the experimental results, the thermal conductivity is observed to be enhanced with the addition of NPs in oil and stability of NF is maintained for longer period. It is also observed that with the rise in temperature, thermal conductivity of NF enhances whereas MO shows marginal changes in thermal conductivity. It is observed by analyzing the theoretical model that the heat transfer characteristics follow the experimental data trend. The superior thermal conductivity of NF improves the heat transfer characteristics of the base fluid. Since high thermally conducting oil affords superior cooling, implementation of NF in the transformer as a coolant is likely to enhance the performance of transformer and maintain its smooth functioning for a longer period of time.