scholarly journals Effects of Plasma Treated Alumina Nanoparticles on Breakdown Strength, Partial Discharge Resistance, and Thermophysical Properties of Mineral Oil-Based Nanofluids

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3610
Author(s):  
Norhafezaidi Mat Saman ◽  
Izzah Hazirah Zakaria ◽  
Mohd Hafizi Ahmad ◽  
Zulkurnain Abdul-Malek
Keyword(s):  
Thermal Conductivity ◽  
Plasma Treatment ◽  
Base Fluid ◽  
Breakdown Strength ◽  
Partial Discharge ◽  
Mineral Oil ◽  
Transformer Oil ◽  
Alumina Nanoparticles ◽  
Discharge Characteristics ◽  
Nano Alumina

Mineral oil has been chosen as an insulating liquid in power transformers due to its superior characteristics, such as being an effective insulation medium and a great cooling agent. Meanwhile, the performance of mineral oil as an insulation liquid can be further enhanced by dispersing nanoparticles into the mineral oil, and this composition is called nanofluids. However, the incorporation of nanoparticles into the mineral oil conventionally causes the nanoparticles to agglomerate and settle as sediment in the base fluid, thereby limiting the improvement of the insulation properties. In addition, limited studies have been reported for the transformer oil as a base fluid using Aluminum Oxide (Al2O3) as nanoparticles. Hence, this paper reported an experimental study to investigate the significant role of cold plasma treatment in modifying and treating the surface of nano-alumina to obtain a better interaction between the nano-alumina and the base fluid, consequently improving the insulation characteristics such as breakdown voltage, partial discharge characteristics, thermal conductivity, and viscosity of the nanofluids. The plasma treatment process was conducted on the surface of nano-alumina under atmospheric pressure plasma by using the dielectric barrier discharge concept. The breakdown strength and partial discharge characteristics of the nanofluids were measured according to IEC 60156 and IEC 60270 standards, respectively. In contrast, the viscosity and thermal conductivity of the nanofluids were determined using Brookfield DV-II + Pro Automated viscometer and Decagon KD2-Pro conductivity meter, respectively. The results indicate that the 0.1 wt% of plasma-treated alumina nanofluids has shown the most comprehensive improvements in electrical properties, dispersion stability, and thermal properties. Therefore, the plasma treatment has improved the nanoparticles dispersion and stability in nanofluids by providing stronger interactions between the mineral oil and the nanoparticles.

Graphite Dispersions as a Basis for Development of High Thermal Conductivity Fluids

2016 ◽  
Vol 881 ◽  
pp. 459-463
Author(s):  
Bruno Santos Potensa ◽  
Carlos Henrique Peres Calixto ◽  
Silvania Lanfredi ◽  
Marcos A.L. Nobre
Keyword(s):  
Thermal Conductivity ◽  
Base Fluid ◽  
Weight Percent ◽  
Processing Parameters ◽  
Mineral Oil ◽  
Thermal Resistivity ◽  
Polar Fluids ◽  
Volumetric Density ◽  
Resistivity Measurements ◽  
Sonication Technique

Both conductivity and thermal resistivity measurements of commercial graphite dispersions in non-aqueous polar fluids and non-polar fluids were carried out. Fluids exhibiting different densities as: mineral oil, ethylene glycol, glycerin bidistilled and liquid vaseline were used. Dispersions of commercial graphite containing 5, 10, 20, 40, 60 and 80 weight percent were prepared by sonication technique. The thermal conductivity of each fluid increases as a function of the increasing of the volumetric density of fluid and of the fraction of graphite. Values of thermal conductivity of graphite dispersion were at around ten times higher than that value of the base-fluid. Effects of processing parameters of graphite dispersions on the magnitude of its thermal conductivity are discussed.

scholarly journals Accumulation Behaviors of Different Particles and Effects on the Breakdown Properties of Mineral Oil under DC Voltage

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2301 ◽  
Author(s):  
Min Dan ◽  
Jian Hao ◽  
Ruijin Liao ◽  
Lin Cheng ◽  
Jie Zhang ◽  
...  
Keyword(s):  
Breakdown Strength ◽  
Simulation Method ◽  
Mineral Oil ◽  
Transformer Oil ◽  
Metal Particles ◽  
Electrical Field ◽  
Dc Voltage ◽  
Particle Properties ◽  
Particle Accumulation ◽  
Field Distortion

Particles in transformer oil are harmful to the operation of transformers, which can lead to the occurrence of partial discharge and even breakdown. More and more researchers are becoming interested in investigating the effects of particles on the performance of insulation oil. In this paper, a simulation method is provided to explore the motion mechanism and accumulation characteristics of different particles. This is utilized to explain the effects of particle properties on the breakdown strength of mineral oil. Experiments on particle accumulation under DC voltage as well as DC breakdown were carried out. The simulation results are in agreement with the experimental results. Having a DC electrical field with a sufficient accumulation time and initial concentration are advantageous for particle accumulation. Properties of impurities determine the bridge shape, conductivity characteristics, and variation law of DC breakdown voltages. Metal particles and mixed particles play more significant roles in the increase of current and electrical field distortion. It is noteworthy that cellulose particles along with metal particles cannot have superposition influences on changing conductivity characteristics and the electrical field distortion of mineral oil. The range of electrical field distortion is enlarged as the particle concentration increases. Changes in the electrical field distribution and an increase in conductivity collectively affect the DC breakdown strength of mineral oil.

Characteristics of Mineral Oil-based Nanofluids for Power Transformer Application

2017 ◽  
Vol 7 (3) ◽  
pp. 1530 ◽  
Author(s):  
I. H. Zakaria ◽  
M. H. Ahmad ◽  
Y. Z. Arief ◽  
N. A. Awang ◽  
N .A. Ahmad
Keyword(s):  
Electrical Properties ◽  
Breakdown Strength ◽  
Power Transformer ◽  
Atmospheric Pressure Plasma ◽  
Mineral Oil ◽  
Transformer Oil ◽  
Before And After ◽  
Cold Atmospheric Pressure Plasma ◽  
The Stability ◽  
Physical Changes

Trends in the field of nanomaterial-based transformer oil show most of the conducted works have focused only on the transformer oil-based nanofluids but limited studies on the stability of transformer oil-based nanofluids. Since mineral oil-based nanofluids still can produce the sedimentation, thus the cold-atmospheric pressure plasma method is proposed to functionally modify the Silicon Dioxide (SiO<sub>2</sub>) nanofiller in order to enhance the electrical properties of the mineral oil-based nanofluids. The AC breakdown strength oil samples before and after modification were measured. It was found that the plasma treated nanofluids have higher AC breakdown voltage compared to pure oil and untreated nanofluids. Also, Fourier Transform Infrared (FTIR) Spectroscopy has been used in this study to analyse the physical changes of oil samples. It is envisaged that the added silica nanofiller has significant effect on electrical properties of the transformer oil-based nanofluids which would enable to the development of an improved class of liquid dielectric for the application of power transformer.

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