Study of Heat Transfer Property of the Transformer Oils on Addition of CuO Nanoparticles

The electrical transformer efficiency and safety depend on the working temperature of the coolant, i.e., insulating oil. The increase in temperature causes the formation of hotspots which ultimately leads to the breakdown in the oil. Adding of nanoparticles (NP) to the oil shows a major trend in the enhancement of the heat transfer property. In this paper, heat transfer properties of mineral oil (MO), MO with NP are compared with vegetable oil (VO) and VO with NP. VO has been gaining significance due to extinct nature of MO. The NP considered in this paper is Cupric Oxide (CuO), which is added to the insulating oil in various weight by volume percentages to study the thermal conductivity (TC) and viscosity. Cupric Oxide is a semi-conductive NP, and it is proved to have enhanced electrical properties such as dielectric constant and breakdown voltage. The enhanced properties of oil can reduce the amount of oil required to cool the entire system thereby optimising the size, cost and weight of the system. The heat transfer properties such as viscosity and thermal conductivity are measured for all the above four types of oil compositions and are compared. Both the viscosity and thermal conductivity are noticed to be affected by the NP size, temperature, base fluid and volume concentration of NP. For enhancement of thermal properties, NP size should be less than 50nm. In this paper, CuO NP is chosen for the study of thermal conductivity, variation of viscosity over a range of NP addition to the base oil.