Next Article in Journal
Numerical Modeling of CO2, Water, Sodium Chloride, and Magnesium Carbonates Equilibrium to High Temperature and Pressure
Next Article in Special Issue
From Thermal to Electroactive Graphene Nanofluids
Previous Article in Journal
Experimental Methodology and Facility for the J69-Engine Performance and Emissions Evaluation Using Jet A1 and Biodiesel Blends
Previous Article in Special Issue
Wettability Control for Correct Thermophysical Properties Determination of Molten Salts and Their Nanofluids
Open AccessArticle

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

1
Institute of Experimental Physics SAS, Watsonova 47, 04001 Kosice, Slovakia
2
Faculty of Electrical Engineering and Informatics, Technical University of Kosice, Letna 9, 04200 Kosice, Slovakia
3
Department of Energy Sciences, Lund University, 22100 Lund, Sweden
4
Division of Building Materials, Lund University, 22100 Lund, Sweden
*
Authors to whom correspondence should be addressed.
This paper is an extended version of our paper published in Conference proceedings of 1st International Conference on Nanofluids (ICNf2019), ISBN eBook en PDF: 978-84-685-3917-1, pp. 95–98.
Energies 2019, 12(23), 4532; https://doi.org/10.3390/en12234532
Received: 30 October 2019 / Revised: 17 November 2019 / Accepted: 25 November 2019 / Published: 28 November 2019
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. View Full-Text
Keywords: magnetic nanofluid; magnetic nanoparticles; thermal conductivity; viscosity; permittivity magnetic nanofluid; magnetic nanoparticles; thermal conductivity; viscosity; permittivity
Show Figures

Graphical abstract

MDPI and ACS Style

Rajnak, M.; Wu, Z.; Dolnik, B.; Paulovicova, K.; Tothova, J.; Cimbala, R.; Kurimský, J.; Kopcansky, P.; Sunden, B.; Wadsö, L.; Timko, M. Magnetic Field Effect on Thermal, Dielectric, and Viscous Properties of a Transformer Oil-Based Magnetic Nanofluid. Energies 2019, 12, 4532.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop