Search results

Sort By:

Limit search:

Analysis of Thermal Field in Mineral Transformer Oil Based Magnetic Fluids

100%

Kosterec M., Kurimský J., Cimbala R., Čonka Z., Kruželák L., Rajňák M., Timko M., Kopčanský P., Vargová B.

Acta Physica Polonica A

2017

vol. 131

issue 4

937-939

Growing interest in the use of magnetic fluids in power systems especially in transformers as insulation and a coolant is nowadays registered. Magnetisable nanofluids, which are used in cooling systems as an alternative to mineral transformer oil, are characterized by lower concentration of magnetic nanoparticles. The magnetic fluid has better heat transfer and dielectric properties such as breakdown than mineral transformer oil and it can be used to improve heat flow, thereby increasing the ability of the active parts to resist failures such as electromagnetic pulses. External magnetic field may be used for forced circulation of magnetic fluid. Magnetic force inside the magnetic fluid can be adequately controlled by adjusting the incident magnetic field. This paper presents thermal distribution, fluid flow and cooling ability of mineral transformer oil and magnetic fluid based on mineral transformer oil. The concentration of Fe₃O₄ magnetic nanoparticles is 0.15% volume of mineral transformer oil. The thermal field is generated by a steel conductor. Thermal distributions in mineral transformer oil and magnetic fluid are investigated and differences for both cases are discussed in the paper.

Generation of Fe₃O₄ Nanoparticle Aggregates in a Ferrofluid Driven by External Electric Field

100%

Kurimský J., Rajňák M., Cimbala R., Paulovičová K., Timko M., Kopčanský P., Kolcun M., Kosterec M., Kruželák L.

Acta Physica Polonica A

2017

vol. 131

issue 4

907-909

In the paper the experimental study of magnetic nanoparticle aggregation in a transformer oil based ferrofluid driven by an external electric field is reported. The studied ferrofluid was composed of the magnetite nanoparticles, oleic acid surfactant, and transformer oil. Generally, it is considered that superparamagnetic nanoparticles do not interact in the absence of external magnetic field. In the paper we present an experimental observation of the particle assembly formation in a direct current external electric field by optical microscopy. During the observation no external magnetic field was applied. A diluted low-polarity ferrofluid drop on a glass surface was exposed to the external static inhomogeneous electric field. It is assumed that induced dipole-dipole interaction and subsequent dielectrophoretic motion give rise to the electrohydrodynamic flow in the fluid after a certain time period. As a result, a visible particle chain was formed at the drop electrical equator. This demonstration is expected to contribute to the understanding of the streamer formation and electrical breakdown in transformer oil based ferrofluids.

Refine search results

2 Acta Physica Polonica A

2 2017

2 Cimbala R.

2 Kopčanský P.

2 Kosterec M.

2 Kruželák L.

2 Kurimský J.

2 Rajňák M.

2 Timko M.

1 Kolcun M.

1 Paulovičová K.

1 Vargová B.

1 Čonka Z.

Search results

Analysis of Thermal Field in Mineral Transformer Oil Based Magnetic Fluids

Generation of Fe₃O₄ Nanoparticle Aggregates in a Ferrofluid Driven by External Electric Field