In-situ high temperature study of the long-term stability and dielectric properties of nanofluids based on TiO2 and SiC dispersions in natural ester oil at various concentrations

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

doi:10.1016/j.molliq.2022.119284

Cited by 28 publications

(5 citation statements)

References 35 publications

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“…19 d). This behavior of nanoparticles dispersed in insulating oil is also reported by Koutras et al 51 . They explain that the surface characteristics of the nanoparticles create traps in the liquid, where free electrons can be easily captured and rapidly released.…”

Section: Discussionsupporting

confidence: 87%

Statistical analysis of the impact of FeO3 and ZnO nanoparticles on the physicochemical and dielectric performance of monoester-based nanofluids

Jiosseu

Jean-Bernard

Mengounou

et al. 2023

Sci Rep

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This article deals with a comparative study of the physicochemical and electrical properties of monoesters of castor oil compared with their counterparts based on FeO3 and ZnO nanoparticles. The results are also compared with those in the literature on triesters, and also with the recommendations of the IEEE C 57.14 standard. The data is analysed statistically using a goodness-of-fit test. The analysis of the viscosity data at 40 °C shows an increase in viscosity. For concentrations of 0.10 wt%, 0.15 wt% and 0.20 wt% these are respectively 5.4%, 9.69%, 12.9% for FeO3 NFs and 7.6%, 9.91% and 12.7% for ZnO NFs. For the same concentrations, the increase in acid number is respectively 3.2%, 2.9%, 2.5% for FeO3 samples and 3.18%, 2.0%, 1.2% for ZnO samples. For the same concentrations, the fire point shows an increment of 4%, 3% and 2% for FeO3 samples and a regression of 8.75%, 6.88% and 5.63% for ZnO samples. As for the breakdown voltage, for the same concentrations we observe respectively an increment of 43%, 27%, 34% for the FeO3. The results show an improvement on partial discharge inception voltage with FeO3 of 24%, 8.13% and 15.21% respectively for the concentrations 0.10 wt%, 0.15 wt% and 0.20 wt%.

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Section: Discussionsupporting

confidence: 87%

Statistical analysis of the impact of FeO3 and ZnO nanoparticles on the physicochemical and dielectric performance of monoester-based nanofluids

Jiosseu

Jean-Bernard

Mengounou

et al. 2023

Sci Rep

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“…The high thermal conductivity of the SiC NPs (165-220 W/(m•K)) with respect to TiO2 could be responsible for the higher improvement concerning the sNF sample [51,52]. Thermal behavior of the two NF samples at these concentration levels is directly affected from the NPs, since they do not suffer from rapid aggregation, as it has been shown in our previous works [13,17,50,53]. When NPs cluster, they lose their ability to increase heat transmission, alter the structural distribution of the suspension system, and ultimately break the irregular movement laws [52].…”

Section: ) Thermal Diffusivity and Conductivitymentioning

confidence: 58%

“…Therefore, the fast electrons at the streamer's tip are captured in shallow traps and the streamer propagation is slown down; as a result, a greater electric field value should be provided to allow the electrons to be freed and span the gap. The potential well distribution for both kinds of NPs is expressed from (7), while (8) corresponds to the charge captured by each of them as a function of time [23,25,53]:…”

Section: ) Lightning Impulse Breakdown Voltagementioning

confidence: 99%

Dielectric and Thermal Response of TiO₂ and SiC Natural Ester Based Nanofluids for Use in Power Transformers

Κούτρας

Peppas²,

Fetsis

et al. 2022

IEEE Access

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The improvement of dielectric and thermal properties of insulating oils used in High Voltage (HV) equipment has been a key part of research over the last three decades. In this study, a natural ester oil is used as matrix oil and dispersions of two semi-conducting nanoparticles (NPs), titanium oxide (TiO2) and silicon carbide (SiC), are prepared in 0.004 weight percentage ratio (0.004% w/w). In terms of thermal features, thermal diffusivity and thermal conductivity are measured over a large temperature range between 25 and 90 o C. By means of the dielectric properties, the Lightning Impulse Breakdown Voltage (LI BDV) of nanofluids (NFs) is measured and compared to the corresponding ones of the matrix. Moreover, the dielectric constant and dielectric dissipation factor (DDF) are determined for the NF and matrix samples in the frequency range of 1 to 10 6 Hz. The obtained results show that the NF containing SiC NPs is characterized from the greatest increase in thermal conductivity, by 58% with respect to natural ester oil's, as well as the lowest dielectric constant in both 25 and 90 o C, most likely due to their higher permittivity and thermal conductivity. Lastly, the LI BDV of the same NF is the most enhanced, by 10% relatively to the matrix, while a numerical model in COMSOL Multiphysics is developed and is found to successfully verify the LI BDV results.INDEX TERMS insulating nanofluid, lightning impulse, dielectric constant, thermal conductivity, numerical model.

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“…(3) The weight fraction of SiO 2 , particle sizes, pH range of water, and sonication processing durations were most influenced input parameters to thermal properties. (4) The contour analysis between the input parameters of two-step method and their outcomes like thermal conductivity, SFC, and viscosity was detailed in analysis. (5) The superior thermal physical properties are 0.9623 W/mK for thermal conductivity, 688 J/kg K for SHC, and 0.00162 for viscosity, respectively.…”

Section: Discussionmentioning

confidence: 99%

“…The enhanced superior heat-transfer medium, or liquid, and the thermic liquid have significant scopes in the thermal-related engineering fields [3]. Thermal fluids have played an essential role in the process and system-based maintaining industries and employed with ideal running temperature [4]. Therefore, to improve the mechanical thermal efficiency, nanofluids are rich medium for heat-transfer liquid [5].…”

Section: Introductionmentioning

confidence: 99%

Influence of Process Parameters and Convective Heat Transfer on Thermophysical Properties of SiO2 Nanofluids by Multiobjective Function Analysis (DFA)

Suprabha

Mahesha

Nanjundappa

2023

Journal of Nanomaterials

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From the requirements, high-performance cooling systems in the applications of solar, heat exchangers, and chemical industries are needed to improve efficiency. The metal-oxides-based nanofluids composed the better thermal properties with exchange of heat-transfer mechanisms. Therefore, this study mainly focused on nanosilicon dioxide materials to produce the nanofluids with blending of water-base medium by two-step techniques. The scanning electron microscope was used to analyze the presence of silicon dioxide nanoparticles from the procured material. During the two-step method input aspects like weight fraction of silicon dioxide (1.5–4.5 wt%), particle sizes (10–30 µm), pH range of water (5–9), and sonication process time (2–4 hr) were considered. The outcomes like thermal conductivity, specific heat capacity, and viscosity were selected as thermal physical properties. The desirability techniques were implemented to identify the best optimal input parameters from the nanofluid processing. From the desirability outcomes, the processed nanosilicon dioxide fluids with respective input parameters were 0.9623 W/mK for thermal conductivity, 688 J/kg K forspecific heat capacity, and 0.00162 for viscosity, respectively. The heat-transfer coefficient was successfully identified with processed nanosilicon dioxide fluids, and the Nusselt number and Reynolds number were attained with respective heat-transfer coefficients.

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In-situ high temperature study of the long-term stability and dielectric properties of nanofluids based on TiO2 and SiC dispersions in natural ester oil at various concentrations

Cited by 28 publications

References 35 publications

Statistical analysis of the impact of FeO3 and ZnO nanoparticles on the physicochemical and dielectric performance of monoester-based nanofluids

Statistical analysis of the impact of FeO3 and ZnO nanoparticles on the physicochemical and dielectric performance of monoester-based nanofluids

Dielectric and Thermal Response of TiO₂ and SiC Natural Ester Based Nanofluids for Use in Power Transformers

Influence of Process Parameters and Convective Heat Transfer on Thermophysical Properties of SiO2 Nanofluids by Multiobjective Function Analysis (DFA)

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In-situ high temperature study of the long-term stability and dielectric properties of nanofluids based on TiO2 and SiC dispersions in natural ester oil at various concentrations

Cited by 28 publications

References 35 publications

Statistical analysis of the impact of FeO3 and ZnO nanoparticles on the physicochemical and dielectric performance of monoester-based nanofluids

Statistical analysis of the impact of FeO3 and ZnO nanoparticles on the physicochemical and dielectric performance of monoester-based nanofluids

Dielectric and Thermal Response of TiO2 and SiC Natural Ester Based Nanofluids for Use in Power Transformers

Influence of Process Parameters and Convective Heat Transfer on Thermophysical Properties of SiO2 Nanofluids by Multiobjective Function Analysis (DFA)

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Dielectric and Thermal Response of TiO₂ and SiC Natural Ester Based Nanofluids for Use in Power Transformers