Experimental Studies on Thermophysical and Electrical Properties of Graphene–Transformer Oil Nanofluid

Abstract

The thermophysical and electrical properties of graphene–transformer oil nanofluid at three weight percentage concentrations (0.01%, 0.03%, and 0.05%) were experimentally studied. Experiments conducted to find viscosity, surface tension, density, specific resistance, electrical conductivity, and dielectric dissipation at various temperatures ranging from 20 °C to 90 °C. It was noted that the nanofluid with 0.05% concentration showed an enhancement of 2.5% and 16.6% for density and viscosity, respectively, when compared to transformer oil. In addition, an average reduction in surface tension is noted to be 10.1% for the maximum concentration of nanofluid. Increase in heat load and concentration improves Brownian motion and decreases the cohesive force between these particles, which results in a reduction in surface tension and increases the heat-transfer rate compared to transformer oil. In addition, for the maximum concentration of nanoparticles, the electrical conductivity of nanofluid was observed to be 3.76 times higher than that of the transformer oil at 90 °C. The addition of nanoparticles in the transformer oil decreases the specific resistance and improves the electrical conductivity thereby enhancing the breakdown voltage. Moreover, the thermophysics responsible for the improvement in thermophysical and electrical properties are discussed clearly, which will be highly useful for the design of power transmission/distribution systems.

Mineral and Ester Nanofluids as Dielectric Cooling Liquid for Power Transformers

“…Characteristics that could condition the convection performance of a coolant oil, such as viscosity, especially with natural flux, were not generally harmed by the presence of nanoparticles. Although slight increases were found [ 49 , 51 , 56 , 58 , 61 , 81 , 86 , 91 , 94 , 111 , 115 , 127 , 180 ], they were just as frequent as those with no effects [ 12 , 25 , 26 , 51 , 59 , 60 , 62 , 64 , 98 , 119 , 121 , 123 , 130 ]. Indeed, reductions in the viscosity were also noticed [ 22 , 51 , 84 , 91 , 95 ].…”

“…Indeed, reductions in the viscosity were also noticed [ 22 , 51 , 84 , 91 , 95 ]. Researchers have demonstrated that the resulting viscosity depends on the nanoparticle concentration [ 26 , 51 , 56 , 58 , 111 , 115 , 126 , 127 , 130 ]. To ensure stability, nanofluids were prepared with low concentrations, and the particles were mainly spherical; it is reasonable that the viscosity was not significantly affected as a result.…”

“…Another idea is that nanoparticles may act as a lubricant between the layers of fluid, as they remain oriented in the flux direction [ 26 ]. The viscosity of nanofluids decreases as the temperature increases, such as with the base fluids [ 49 , 51 , 56 , 58 , 59 , 64 , 86 , 94 , 123 , 127 ], and seems to be enhanced by the presence of external electric fields, as a function of the nanoparticle concentration [ 71 , 119 ]. Nevertheless, an essential modification was identified, which changed the behavior of the base fluid from a Newtonian to a non-Newtonian fluid at a determinate concentration of nanoparticles [ 22 , 26 , 143 ] or at low temperatures [ 143 ], due to an increase in the number of interactions [ 130 ].…”

Dielectric Fluids for Power Transformers with Special Emphasis on Biodegradable Nanofluids

“…Almeida et al [132] mixed graphene nanoparticles with mineral transformer oil to test thermophysical and dielectric properties of the resulting nanofluid. The samples were sorted by the concentrations 0.01 wt%, 0.03 wt%, and 0.05 wt%.…”

Comparison between multi-walled carbon nanotubes and Titanium dioxide nanoparticles as additives on performance of Turbine meter oil nano lubricant

“…Nano lubricants are a solution to this challenge and have received much attention in recent years; studies have indicated that adding small amounts of nano additives (about 0.2 to 2%) to the base fluid can improve its tribological properties [4][5][6][7]. Various types of nanoparticles, such as carbon-based materials [8,9], metal oxides [10][11][12], and metals [13,14], have been used as additives. The nanoparticles have unique features due to their high specific surface area and smaller size than other materials.…”