7 research outputs found
The impact of electromagnetic radiation on the degradation of magnetic ferrofluids
This article deals with magnetic nano-fluids, which are the part of transformer
oil ITO 100 and their behavior is influenced by a permanent magnetic field. We performed
an IRC analysis in the time domain on the three different samples. Measurements
were made before and after radiation of an electromagnetic field. The main objective was
to examine changes in the properties of the samples due to the influence of the electromagnetic
field. The measurements depend on the orientation of the external magnetic
field. This behavior occurs especially during the structuring of the nanoparticles in the
sample exposed to the magnetic field. These processes change the polarization of the
liquid because the nanoparticles concentration is contained in the fluid
Analysis of Thermal Field in Mineral Transformer Oil Based Magnetic Fluids
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
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