Ultrastable Natural Ester-Based Nanofluids for High Voltage Insulation Applications

Peppas, Georgios D.; Bakandritsos, Aristides; Charalampakos, Vasilios P.; Pyrgioti, E.; Tuček, Jiří; Zbořil, Radek; Gonos, Ioannis F.

doi:10.1021/acsami.6b06084

Cited by 75 publications

(82 citation statements)

References 48 publications

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“…Therefore, the suitable addition of nanoparticles into transformer oil needs to be accomplished to ensure the optimized properties of the resulting ferrofluids. The agglomeration of magnetic nanoparticles may be reduced by the use of certain surfactants, surface modification techniques and ultrasonic agitation [72][73][74][75].…”

Section: (B) Stability Of Ferrofluidsmentioning

confidence: 99%

Study of Dielectric Breakdown Performance of Transformer Oil Based Magnetic Nanofluids

Rafiq

et al. 2017

Energies

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Abstract:Research on the transformer oil-based nanofluids (NFs) has been raised expeditiously over the past decade. Although, there is discrepancy in the stated results and inadequate understanding of the mechanisms of improvement of dielectric nanofluids, these nanofluids have emerged as a potential substitute of mineral oils as insulating and heat removal fluids for high voltage equipment. The transformer oil (TO) based magnetic fluids (ferrofluids) may be regarded as the posterity insulation fluids as they propose inspiring unique prospectus to improve dielectric breakdown strength, as well as heat transfer efficiency, as compared to pure transformer oils. In this work, transformer oil-based magnetic nanofluids (MNFs) are prepared by dispersal of Fe 3 O 4 nanoparticles (MNPs) into mineral oil as base oil, with various NPs loading from 5 to 80% w/v. The lightning impulse breakdown voltages (BDV) measurement was conducted in accordance with IEC 60897 by using needle to sphere electrodes geometry. The test results showed that dispersion of magnetic NPs may improve the insulation strength of MO. With the increment of NPs concentrations, the positive lightning impulse (LI) breakdown strength of TO is first raised, up to the highest value at 40% loading, and then tends to decrease at higher concentrations. The outcomes of negative LI breakdown showed that BDV of MNFs, with numerous loadings, were inferior to the breakdown strength of pure MO. The 40% concentration of nanoparticles (optimum concentration) was selected, and positive and negative LI breakdown strength was also further studied at different sizes (10 nm, 20 nm, 30 nm and 40 nm) of NPs and different electrode gap distances. Augmentation in the BDV of the ferrofluids (FFs) is primarily because of dielectric and magnetic features of Fe 3 O 4 nanoaprticles, which act as electron scavengers and decrease the rate of free electrons produced in the ionization process. Research challenges and technical difficulties associated with ferrofluids for practical applications are mentioned. The advantages and disadvantages linked with magnetic fluids are also presented.

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Section: (B) Stability Of Ferrofluidsmentioning

confidence: 99%

Study of Dielectric Breakdown Performance of Transformer Oil Based Magnetic Nanofluids

Rafiq

et al. 2017

Energies

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“…In the case of nanofluids' applications in transformers, the main research is related to the improvement of the dielectric properties of the base liquids. There are many publications confirming the positive influence of electro-insulating liquids' modifications, with nanomaterials on their dielectric properties and phenomena such as breakdown voltage [40][41][42][43], streamer propagation [44], electrical conductivity, and the dissipation factor [45][46][47][48][49]. In addition, as reported in the literature [50,51], fullerene C 60 can also be used to absorb free radicals arising from the aging of vegetable oils.…”

Section: Introductionmentioning

confidence: 88%

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

2018

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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.

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“…Nanofluids, formed by adding nanoscale particles to the base fluid, are stable and homogenous suspensions that present advanced performance of electrical insulation and thermal conductivity [1][2][3][4][5][6]. In recent years, nanofluids with various kinds of nanoparticles have promising potential applications in fields including electric engineering, microelectronics, biomedicine, and energy storage [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Enhanced Electrical Insulation and Heat Transfer Performance of Vegetable Oil Based Nanofluids

Yao

Huang

et al. 2018

Journal of Nanomaterials

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Nanoparticles enhance the electrical insulation and thermal properties of vegetable oil, and such improvements are desirable for its application as an alternative to traditional insulating oil for power transformers. However, the traditional method of insulating nanofluids typically achieves high electrical insulation but low thermal conductivity. This work reports an environmentally friendly vegetable oil using exfoliated hexagonal boron nitride (h-BN) showing high thermal conductivity and high electrical insulation. Stable nanofluids were prepared by liquid exfoliation of h-BN in isopropyl alcohol. With 0.1 vol.% of the nano-oil, the AC breakdown voltage increased by 18% at 25 ∘ C and 15% at 90 ∘ C. Both the positive and negative lightning impulse breakdown voltages of the nanooil were also enhanced compared with those of the pure oil. Moreover, the thermal conductivity of the nano-oil increased by 11.9% at 25 ∘ C and 14% at 90 ∘ C. Given its high thermal conductivity, the nano-oil exhibited faster heating and cooling effects than the pure oil. Nano-oils with an electric field (either DC or AC) displayed a faster thermal response than that without an electric field. The reason is that h-BN is oriented under the electric field and formed a thermal network to increase the heat transfer.

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Ultrastable Natural Ester-Based Nanofluids for High Voltage Insulation Applications

Cited by 75 publications

References 48 publications

Study of Dielectric Breakdown Performance of Transformer Oil Based Magnetic Nanofluids

Study of Dielectric Breakdown Performance of Transformer Oil Based Magnetic Nanofluids

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

Enhanced Electrical Insulation and Heat Transfer Performance of Vegetable Oil Based Nanofluids

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