Maghemite Nanofluid Based on Natural Ester: Cooling and Insulation Properties Assessment

Abstract

The objective of this work is to study the effect that the addition of magnetic nanoparticles to a natural ester has on its properties and its cooling capacity. Some samples of ferrofluid (natural ester with maghemite) have been prepared using different concentrations. These have been characterized by measuring their thermo-hydraulic and dielectric properties, to find an optimal concentration. Then, the cooling capacities of the optimal nanofluid and the base fluid have been tested in a transformer immersed in these liquids. The experimental platform allowed the measurement of temperatures in different locations at different load levels. Parallel simulations of these tests have been carried out with a Computational Fluid Dynamics model of the experimental platform. The results show an improvement of the insulating capacity of the base fluid with the addition of maghemite nanoparticles, and an enhanced cooling capacity.

Titania Nanofluids Based on Natural Ester: Cooling and Insulation Properties Assessment

“…Thus, from the dielectric standpoint, 0.5 kg/m 3 is the optimal concentration. This tendency is usually found in similar studies, including the one carried out with the same base fluid and Fe2O3 nanoparticles [29].…”

“…Regarding other typical dielectric parameters measured in this kind of study, the Dielectric Dissipation Factor (tan δ) is affected by the presence of nanoparticles, and it is slightly increased, from 0.0260 to 0.0295, up 13.5%, depending on the concentration (Figure 6). On this occasion the effect is less pronounced than that seen with the Fe2O3 nanoparticles with the same base fluid, up to 119.7% in the concentrations studied [29]. This difference is also noticed when focusing on the resistivity of the samples, with a slight increase with the concentration of nanoparticles, from 6.081 GΩ•m to 6.642 GΩ•m, up to 9.2% ( Figure 6) against that seen with the ferrofluid [29], whose resistivity decreased with the nanoparticles' concentration, up to −31.4%.…”

“…In this sense, a study about low-concentrated maghemite (one of the most promising nanoparticles) nanofluids was carried out, whose results are published in [29]. This first study includes, among other things, a characterization of the main properties of several Fe 2 O 3 nanofluids in a narrow range of concentrations, as well as one of the base fluid, for comparison's sake.…”

“…Among the further investigations proposed in [29], the realization of similar tests with non-magnetic nanoparticles has been carried out, emphasizing a real application of the nanofluids, at the laboratory scale. The objective was to check whether the beneficial effect of the TiO 2 nanoparticles on the base fluid tested would be similar for those with magnetic nanoparticles.…”

Effect of TiO2 and ZnO Nanoparticles on the Performance of Dielectric Nanofluids Based on Vegetable Esters During Their Aging

“…On the other hand, it should be highlighted that although dielectric properties are critical characteristics of insulating fluids, it is significantly important that nanofluids besides possess suitable cooling properties. For this reason, some authors have focused their works on these characteristics [10][11][12][13]. Their results conclude that magnetic fluids reduce temperatures at transformer winding and top oil, which would diminish the aging rate as it happens with pure dielectric liquids [14,15].…”