Effects of Nanoparticles Materials on Heat Transfer in Electro-Insulating Liquids

Abstract

This paper discusses the effect of doping of electro-insulating liquids with nanoparticle materials on the thermal properties of the obtained nanoliquids and heat transport in the transformer. Mineral oil, synthetic ester, and natural ester were used as base liquids. The effectiveness of doping base liquids with nanoparticles was supported by ultraviolet-visible (UV/VIS) measurements. In turn, Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) confirmed the absence of intermolecular interactions (i.e., hydrogen bonding). The influence of modification of electro-insulating liquids with fullerene C60 and titanium dioxide TiO2 nanoparticles on such thermal properties as thermal conductivity, specific heat, kinematic viscosity, density, and thermal expansion was investigated. Based on these properties and the theory of similarity, the cooling efficiency of the transformer filled with the analyzed nanofluids was determined. Nanofluids’ cooling effectiveness was compared with the cooling effectiveness of the base liquids. This comparison was supported by an analysis of Grashof, Prandtl, and Nusselt numbers. It has been shown that the modification of electro-insulating liquids with nanoparticles widely used in order to improve their dielectric properties, such as C60 and TiO2, does not have a significant influence on their thermal properties. The addition of fullerene C60 caused an increase in kinematic viscosity, which was compensated by the increase in specific heat. In the case of TiO2, the addition of this nanoparticle resulted in an increase in kinematic viscosity and a decrease in specific heat, which were balanced out by the increase in thermal conductivity. In summary, the heat exchange-capacity of liquids did not change due to doping with nanoparticles.

Various Aging Processes in a Paper-Natural Ester Insulation System in the Presence of Copper and Moisture

“…The measured natural ester is an unsaturated ester, as evidenced from Figure 13 (data from 3 measurement) by the presence of absorption bands with a maximum at 3009 cm −1 (=C-H stretching symmetric vibration of the cis double bonds) and at cm −1 (C=C stretching vibration of cis-disubstituted olefins, RHC=CHR) in its spectrum [38]. The FT-IR spectrum also shows some other characteristic absorbance peaks representing vibrations of specific functional groups.…”

Surface Tracking of MgO/Epoxy Nanocomposites: Effect of Surface Hydrophobicity

“…The science and technology of nanodielectrics, which are considered to be the next generation of insulating materials, have developed rapidly since the proposal of "Nanometric Dielectric" by Lewis [10], in 1994, and the redefinition of the term "Nanodielectric", by Frechette [11] in 2001. Remarkable thermal, mechanical, and dielectric properties have been achieved in nanodielectrics, due to the induced interfaces between the nanofillers and the polymer matrix [7-9, [12][13][14][15][16][17][18]. Improved tracking resistance has also been achieved in nanodielectrics, by enhancing thermal conductivity [9,19], stability of the chains [7], surface charge dissipation [20], etc.…”

Electrical Strength of Natural Esters Doped by Iron Nanopowder in a Hydrophobic Carbon Shell

“…In [5], the authors described the effect of activated bentonite on aged transformer oil, where the electrical, physical, chemical, and thermal properties were significantly improved. The studies presented in [6,7] show the analysis of thermal properties of mineral oil, synthetic ester, and natural ester after admixture of fullerene C 60 nanoparticles and titanium oxide TiO 2 , which also showed positive effects on oils. There are also many studies on the use of iron oxides in electro-insulating liquids in the literature.…”

“…The recent interest in the development of nanomaterials has led researchers to the study of their electrical properties and the applications that they may have as insulating materials. The articles [5][6][7][8] focus on research in electro-insulating liquids. In [5], the authors described the effect of activated bentonite on aged transformer oil, where the electrical, physical, chemical, and thermal properties were significantly improved.…”