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Permittivity of (40 nm and 80 nm) alumina nanofluids in ethylene glycol at different temperatures

dc.contributor.authorCoelho, Maria de Fátima
dc.contributor.authorRivas, M.A.
dc.contributor.authorNogueira, Elisabete Maria
dc.contributor.authorIglesias, T.P.
dc.date.accessioned2022-05-02T14:29:26Z
dc.date.available2022-05-02T14:29:26Z
dc.date.issued2021
dc.description.abstractThis article studies the effective permittivity of alumina nanofluids (aluminium oxide) in ethylene glycol. Two nanoparticle sizes (40 nm and 80 nm) were considered and the measurements were carried out at various concentrations (up to 2% in volume) and at six different temperatures (from 298.15 K to 348.15 K). An empirical equation is proposed that allows to obtain the permittivity value at any concentration or temperature in the studied ranges. The influence of the volume fraction, nanoparticle size and the temperature on relative permittivity is shown. When compared to the previous published values for alumina (40 nm) in water, current results show the influence of the base fluid. The enhancement of permittivity was calculated, and its behaviour was analysed. Smaller sized particles have the highest values of permittivity and enhancement. Theoretical models in the study of permittivity are applied. The poor predictions of classical models are attributed to the positive behaviour of the permittivity change on mixing for these nanofluids. The contributions to permittivity from ethylene glycol and nanoparticles are separated in two distinct terms in the variable index equation. The permittivity change on mixing calculated from this equation points out that the nanoparticles are the main responsible for the unusual permittivity increment in these colloids.pt_PT
dc.description.sponsorshipWe appreciate the financial support ED431C 2020-06 provided by the Xunta de Galicia (Spain). M.F.C. thanks Instituto Superior de Engenharia do Porto for granting leave of absence to carry out experimental work at University of Vigo.pt_PT
dc.description.versioninfo:eu-repo/semantics/publishedVersionpt_PT
dc.identifier.doi10.1016/j.jct.2021.106423pt_PT
dc.identifier.issn0021-9614
dc.identifier.urihttp://hdl.handle.net/10400.22/20435
dc.language.isoengpt_PT
dc.peerreviewedyespt_PT
dc.publisherElsevierpt_PT
dc.relation.publisherversionhttps://www.sciencedirect.com/science/article/pii/S0021961421000380pt_PT
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/4.0/pt_PT
dc.subjectAluminapt_PT
dc.subjectNanofluidspt_PT
dc.subjectNanoparticlespt_PT
dc.subjectRelative permittivitypt_PT
dc.subjectTheoretical modelspt_PT
dc.titlePermittivity of (40 nm and 80 nm) alumina nanofluids in ethylene glycol at different temperaturespt_PT
dc.typejournal article
dspace.entity.typePublication
oaire.citation.startPage106423pt_PT
oaire.citation.titleThe Journal of Chemical Thermodynamicspt_PT
oaire.citation.volume158pt_PT
person.familyNameCoelho
person.familyNameNogueira
person.givenNameMaria de Fátima
person.givenNameElisabete Maria
person.identifier.ciencia-idD612-C5AF-5DBC
person.identifier.orcid0000-0003-3613-8629
person.identifier.orcid0000-0003-2079-252X
person.identifier.ridB-6679-2017
person.identifier.scopus-author-id55463688500
rcaap.rightsopenAccesspt_PT
rcaap.typearticlept_PT
relation.isAuthorOfPublication7955b7e4-c128-4ed7-90b3-ece2831d0538
relation.isAuthorOfPublicationd2c129fe-6e4e-421e-bab6-37415633b846
relation.isAuthorOfPublication.latestForDiscovery7955b7e4-c128-4ed7-90b3-ece2831d0538

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