Magnetic Field Effect on Thermal, Dielectric, and Viscous Properties of a Transformer Oil-Based Magnetic Nanofluid

Abstract

Progress in electrical engineering puts a greater demand on the cooling and insulating properties of liquid media, such as transformer oils. To enhance their performance, researchers develop various nanofluids based on transformer oils. In this study, we focus on novel commercial transformer oil and a magnetic nanofluid containing iron oxide nanoparticles. Three key properties are experimentally investigated in this paper. Thermal conductivity was studied by a transient plane source method dependent on the magnetic volume fraction and external magnetic field. It is shown that the classical effective medium theory, such as the Maxwell model, fails to explain the obtained results. We highlight the importance of the magnetic field distribution and the location of the thermal conductivity sensor in the analysis of the anisotropic thermal conductivity. Dielectric permittivity of the magnetic nanofluid, dependent on electric field frequency and magnetic volume fraction, was measured by an LCR meter. The measurements were carried out in thin sample cells yielding unusual magneto-dielectric anisotropy, which was dependent on the magnetic volume fraction. Finally, the viscosity of the studied magnetic fluid was experimentally studied by means of a rheometer with a magneto-rheological device. The measurements proved the magneto-viscous effect, which intensifies with increasing magnetic volume fraction.

Special Issue of the 1st International Conference on Nanofluids (ICNf19)

“…This Editorial note was dedicated to the 1st International Conference on Nanofluids and the 2 nd European Symposium of Nanofluids (ICNf2019). After a short report about the conference, the successful invited submissions [7][8][9][10][11][12][13][14][15] to this Special Issue of Energies were introduced. We believe that the articles in this special issue, whose main parts were presented during the conference, will contribute significantly to the development of nanofluid science and challenges in heat transfer and energy applications.…”

“…Rajnak et al [10] evaluate the thermophysical properties, such as thermal conductivity, dielectric permittivity and viscosity, of magnetic nanofluid containing iron oxide nanoparticles and commercial oil. The influence of nanoparticle content and magnetic field on these properties is studied, showing in particular an anisotropy effect and a potential application of these nanofluids in power transformers.…”

“…Funding: The APC of papers [8,[10][11][12][13][14][15] was funded by the COST Action Nanouptake (CA15119).…”

Modification of Diamagnetic Materials Using Magnetic Fluids

“…1, b). On the other hand, one can obtain important information from magnetization curves on the magnetic particle volume fraction in a fluid, as well as the magnetic diameter of the nanoparticles, as reported in various studies on magnetic fluids [14][15][16]. From Fig.…”

Dielectric Performance of Magneto-Nanofluids for Advancing Oil-Immersed Power Transformer

“…Magneto-Nanofluids (ferrofluids) contain evenly distributed NPs-based fluid which use magnetic NPs to achieve superior dielectric property for transformer oil [8]. Recently, many types of research have been carried out on magneto-NFs that show promising dielectric and thermal properties as transformer oil [9]- [11].…”