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Electrical conduction currents of a mineral oil-based nanofluid in needle-plane configuration
KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.ORCID iD: 0000-0002-8173-8765
KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.ORCID iD: 0000-0002-6375-6142
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.ORCID iD: 0000-0003-4774-4341
2016 (English)In: 2016 IEEE CONFERENCE ON ELECTRICAL INSULATION AND DIELECTRIC PHENOMENA (IEEE CEIDP), IEEE conference proceedings, 2016, p. 687-690Conference paper, Published paper (Refereed)
Abstract [en]

We present experiments and simulations on the electrical conduction currents of purified transformer oil with and without surface-modified MgO nanoparticles. Results show that on the injection regime of the voltage-current characteristics, nanoparticles increase the charge production in the fluid. It is also found that the conduction currents in the space-charge-limited regime increased at a lower rate as a function of the voltage in the presence of nanoparticles. The numerical simulations suggest electron attachment is increased due to the nanoparticles, leading to larger accumulation of negative ionic space charge close to the needle in the space-charge-limited regime. It is concluded that electron attachment may be significantly increased with nanoparticles, becoming an important process of electrical conduction in nanofluids.

Place, publisher, year, edition, pages
IEEE conference proceedings, 2016. p. 687-690
Series
Conference on Electrical Insulation and Dielectric Phenomena Annual Report, ISSN 0084-9162
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-201297DOI: 10.1109/CEIDP.2016.7785694ISI: 000391639700142Scopus ID: 2-s2.0-85009823702ISBN: 978-1-5090-4654-6 (print)OAI: oai:DiVA.org:kth-201297DiVA, id: diva2:1073970
Conference
IEEE Conference on Electrical Insulation and Dielectric Phenomena (IEEE CEIDP), OCT 16-19, 2016, Toronto, CANADA
Note

QC 20170214

Available from: 2017-02-14 Created: 2017-02-14 Last updated: 2019-08-01Bibliographically approved
In thesis
1. Pre-breakdown Phenomena in Mineral Oil Based Nanofluids
Open this publication in new window or tab >>Pre-breakdown Phenomena in Mineral Oil Based Nanofluids
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Mineral oil is a dielectric liquid commonly used in high voltage equipment such as power transformers. Interestingly, it has been experimentally observed that the dielectric strength of the mineral oil is improved when nanoparticles are added. However, the mechanisms behind these improvements are not well understood, hindering the further innovation process of these so-called nanofluids. This thesis aims to contribute to the understanding of the mechanisms explaining the dielectric strength improvement of the base oil when nanoparticles are added.For this, several experiments and numerical simulations are performed in this thesis. The initiation voltage of electric discharges infive different kind of nanofluids was measured. The large data set obtained allowed to cast experimental evidence on the existing hypotheses that are used to explain the effect of nanoparticles. It is found that hydrophilic nanoparticles hinder the electric discharge initiation from anode electrodes. On the other hand, electric discharge initiation from cathode electrodes was hindered by nanoparticles with low charge relaxation time.The electric currents in mineral oil and nanofluids were also measured under intense electric fields (up to 2GV/m). It is found that the addition of certain nanoparticles increases the measured currents. The possible physical mechanisms explaining the measured currents inmineral oil with and without nanoparticles were thoroughly discussed based on results of numerical simulations. Preliminary parameters used in this thesis to model these mechanisms led to a good agreement between the measured and simulated electric currents.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2019. p. 69
Series
TRITA-EECS-AVL ; 2019:58
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-255605 (URN)978-91-7873-241-8 (ISBN)
Public defence
2019-09-06, Kollegiesalen, Brinellvägen 8, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20190802

Available from: 2019-08-02 Created: 2019-08-01 Last updated: 2019-08-02Bibliographically approved

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Pallon, L. K. H.

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