Dielectric strength and stability of natural ester oil based TiO2 nanofluids

Κούτρας, Κωνσταντίνος; Naxakis, Ioannis; Αντωνέλου, Ασπασία; Charalampakos, Vasilios P.; Pyrgioti, E.; Yannopoulos, Spyros N.

doi:10.1016/j.molliq.2020.113901

Cited by 57 publications

(58 citation statements)

References 28 publications

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“…Koutras et al [109] mixed EnvirotempTM FR3TM NE with TiO 2 nanoparticles of an average nominal diameter of 21 nm. The mean AC-BDV was enhanced by 22.4% at concentration 0.02 vol% and improvement of dielectric properties were proven at all examined concentrations (0.005-0.04 vol%).…”

Section: Ac-bdvmentioning

confidence: 99%

Dielectric Fluids for Power Transformers with Special Emphasis on Biodegradable Nanofluids

2021

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This review is focused on the research of dielectric fluids, especially commonly used power transformer oils enhanced by nanoparticles, i.e., nanofluids. There are differences between various combinations of base fluids and nanoparticles prepared in different ways. The main goal of this review was to present recent research in this field sorted by the used nanoparticles. Nanofluids based on mineral oils, natural, or synthetic esters were investigated in terms of the nature of nanoparticles, particularly Al2O3, TiO2, Fe2O3, Fe3O4, graphene, fullerene, and others. The combinations of environmentally friendly oils and nanoparticles were presented. Finally, the article focused on the description of current dielectric fluids usable in power transformers and the possibilities of improving new and existing fluids with nanoparticles, especially their physical, dielectric, and chemical properties, but with regard to environmental aspects.

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Section: Ac-bdvmentioning

confidence: 99%

Dielectric Fluids for Power Transformers with Special Emphasis on Biodegradable Nanofluids

2021

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“…When compared TiO 2 nanoparticles with Fe 2 O 3 ones in [13], TiO 2 nanoparticles could enhance the BDV up to about 67%, while the enhancement was limited to 20% with Fe 2 O 3 nanoparticles. Also, TiO 2 nanoparticles at 0.02 vol% enhanced the BDV up to 22% for Envirotemp™ FR3 natural ester oil from Cargill Industrial Specialties-Minneapolis, MN, USA [14]. In spite of TiO 2 nanoparticles proved several enhancements in dielectric properties with different natural ester oils, they failed to enhance thermal conductivity of these oils [15].…”

Section: Introductionmentioning

confidence: 96%

Investigation of the Effect of Sonication Time on Dispersion Stability, Dielectric Properties, and Heat Transfer of Graphene Based Green Nanofluids

et al. 2021

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Natural ester oils are the current target of many industries and electrical utilities as electrically insulating fluids to replace the conventional mineral oils. However, previously investigated most natural ester oils are based on edible products, causing a negative impact on the food crisis. Accordingly, nonedible green nanofluids based on cottonseed oil have been targeted in the present study. Additive graphene nanoparticles (0.0015 wt%, 0.003 wt%, 0.006 wt%, and 0.01 wt%) along with surfactant sodium dodecylbenzene sulfonate (SDBS) were used (1:1) due to their promising impact on dielectric and thermal properties. Experimental methods introduced were including characterization of graphene and preparation of dielectric nanofluids (DNFs). The main concern for any nanofluid to be usable in transformer applications is its long-term stability. The effect of various ultrasonication period (10, 20, 30 and 60minute) on short-term stability of nanofluids was preliminary investigated by visual inspection, highest short-term stability was obtained at 30-min and 60-min. Considering short-term stability results, the two most stable samples were investigated and compared for long-term stability through Ultraviolet visible (UV-Vis) spectroscopy to find the suitable ultrasonication time. In addition, dielectric and thermal properties of these samples were investigated and compared. Physical mechanisms were discussed for the obtained enhancements considering the effect of ultrasonication period on the number of dispersed nanoparticle sheets per unit volume and the corresponding effect on dielectric and thermal properties.

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“…Statistics have shown that the major aspects that lead to the limitation of the power transformer lifespan, and ultimately its failure, are based on insulation, which is mainly made of a combination of dielectric liquid and insulating paper impregnated in it [4][5][6][7]. In contrast to the mineral oils used conventionally, natural ester oils (NEO) are characterized by unique and preferable properties from the industry side, such as rapid biodegradability, high moisture tolerance, less flammability and increased lifetime in comparison to mineral oils [8][9][10][11][12]. Apart from that, their higher relative permittivity is also very important, as it can match that of solid insulation in order to limit electric stress in high loading situations [13].…”

Section: Introductionmentioning

confidence: 99%

“…With regard to their type, the influence of metal oxide NPs, i.e., TiO 2 , Al 2 O 3 , ZnO, Fe 2 O 3 and Fe 3 O 4 , on the dielectric and thermal performance of biodegradable oils has been thoroughly investigated [8,11,12,[21][22][23][24][25][26]. Olmo et al [21] reported that the addition of TiO 2 NPs (10-20 nm size) resulted in AC breakdown voltage (AC BDV) enhancement by 33.2% at a volume percentage ratio of 0.5 kg/m 3 , while in different concentrations the enhancement ranged from 7.6 to 30.4%.…”

Section: Introductionmentioning

confidence: 99%

“…Most of them consider the charged NPs as electron traps caused by the higher permittivity or conductivity of the colloidal suspensions with respect to the base liquid [31]. Consequently, it has been proposed that conductive NPs are more efficient; however, recent studies have demonstrated that semi-conductive or even dielectric NPs can indeed influence the streamer propagation significantly [11,34,35].…”

Section: Introductionmentioning

confidence: 99%

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Breakdown Performance and Partial Discharge Development in Transformer Oil-Based Metal Carbide Nanofluids

et al. 2022

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In this work, the influence of semi-conductive SiC nanoparticles on the AC breakdown voltage and partial discharge development in natural ester oil FR3 is examined. Primarily, the dielectric constant and the electrical conductivity of the nanoparticles are measured following the broadband dielectric spectroscopy technique. The nanoparticles are added into the matrix following the ultrasonication process in three weight percentage ratios in order for their effect to be evaluated as a function of their concentration inside the base oil. The processing of the results reveals that the nanofluid containing SiC nanoparticles at 0.004% w/w demonstrates the highest AC dielectric strength improvement and shows the greatest resistance to the appearance of partial discharge activity. The mechanisms behind the aforementioned results are discussed in detail and confirmed by the broadband dielectric spectroscopy technique, which reveals that this particular nanofluid sample is characterized by lower dielectric constant and electrical conductivity than the one with double the weight percentage ratio.

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Dielectric strength and stability of natural ester oil based TiO2 nanofluids

Cited by 57 publications

References 28 publications

Dielectric Fluids for Power Transformers with Special Emphasis on Biodegradable Nanofluids

Dielectric Fluids for Power Transformers with Special Emphasis on Biodegradable Nanofluids

Investigation of the Effect of Sonication Time on Dispersion Stability, Dielectric Properties, and Heat Transfer of Graphene Based Green Nanofluids

Breakdown Performance and Partial Discharge Development in Transformer Oil-Based Metal Carbide Nanofluids

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