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

Michal Rajnak, Zan Wu, Bystrik Dolnik, Katarina Paulovicova, Jana Tothova, Roman Cimbala, Juraj Kurimský, Peter Kopcansky, Bengt Sunden, Lars Wadsö and Milan Timko
Additional contact information
Michal Rajnak: Institute of Experimental Physics SAS, Watsonova 47, 04001 Kosice, Slovakia
Zan Wu: Department of Energy Sciences, Lund University, 22100 Lund, Sweden
Bystrik Dolnik: Faculty of Electrical Engineering and Informatics, Technical University of Kosice, Letna 9, 04200 Kosice, Slovakia
Katarina Paulovicova: Institute of Experimental Physics SAS, Watsonova 47, 04001 Kosice, Slovakia
Jana Tothova: Faculty of Electrical Engineering and Informatics, Technical University of Kosice, Letna 9, 04200 Kosice, Slovakia
Roman Cimbala: Faculty of Electrical Engineering and Informatics, Technical University of Kosice, Letna 9, 04200 Kosice, Slovakia
Juraj Kurimský: Faculty of Electrical Engineering and Informatics, Technical University of Kosice, Letna 9, 04200 Kosice, Slovakia
Peter Kopcansky: Institute of Experimental Physics SAS, Watsonova 47, 04001 Kosice, Slovakia
Bengt Sunden: Department of Energy Sciences, Lund University, 22100 Lund, Sweden
Lars Wadsö: Division of Building Materials, Lund University, 22100 Lund, Sweden
Milan Timko: Institute of Experimental Physics SAS, Watsonova 47, 04001 Kosice, Slovakia

Energies, 2019, vol. 12, issue 23, 1-11

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.

Keywords: magnetic nanofluid; magnetic nanoparticles; thermal conductivity; viscosity; permittivity (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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