Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Electric Conduction in Mineral Oil based ZnONanofluids under Intense Electric Fields
KTH, School of Electrical Engineering and Computer Science (EECS).ORCID iD: 0000-0002-8173-8765
KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.ORCID iD: 0000-0002-6375-6142
Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.ORCID iD: 0000-0001-5867-0531
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The electric conduction processes in mineral oil based ZnO–C18 nanofluids under intense electric fields are investigated. For this, conduction currents are measured usinga needle-plane electrode configuration. Furthermore, an electrohydrodynamic (EHD) model is used here to discuss the charge generation mechanisms and the electronic properties of the ZnO–C18 nanofluids. The analysis of the conduction currents shows that ZnO–C18 nanoparticles increase the generation of charge carriers, and at the same time they augment the scavenging of quasi-free electrons compared with the measurements with mineral oil only. It is found that the existing nanoparticle electron scavenging model reported in the literature grossly underestimates the electron scavenging process here reported. A new analytical formulation for the nanoparticle electron scavenging process is proposed. The EHD model is also used to simulate the electric conduction processes just before negative streamer inception in mineral oil and ZnO–C18 nanofluids. It is shown that ZnO–C18 nanoparticles hinder the streamer initiation process by reducing the effective electric field at the tip of the needle. This electric field reduction is caused by the combined effect of the generation of charge carriers and the electron scavenging of ZnO–C18 nanoparticles.

National Category
Electrical Engineering, Electronic Engineering, Information Engineering Nano Technology
Research subject
Electrical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-255604OAI: oai:DiVA.org:kth-255604DiVA, id: diva2:1340015
Note

QC 20190802

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

Open Access in DiVA

No full text in DiVA

Authority records BETA

Aljure, MauricioBecerra Garcia, MarleyPourrahimi, Amir Masoud

Search in DiVA

By author/editor
Aljure, MauricioBecerra Garcia, MarleyPourrahimi, Amir Masoud
By organisation
School of Electrical Engineering and Computer Science (EECS)Electromagnetic Engineering
Electrical Engineering, Electronic Engineering, Information EngineeringNano Technology

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 222 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf