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Orientador(es)
Resumo(s)
The effective permittivity and electrical conductivity of copper oxide (12 nm) nanofluids in water are studied. The measurements were carried out at various concentrations (up to 2% in volume) and at six temperatures (from 298.15 K to 348.15 K). Empirical equations were used for describing the conductivity and the permittivity of the experimental data. The study shows the influence of the volume fraction, the temperature on relative permittivity and electrical conductivity. When compared with the previously published values for alumina (15 nm) in water, present results show the influence of the nanoparticle’s nature. The enhancement of both permittivity and electrical conductivity were calculated and their behaviour was analysed. It is discussed whether their positive values can be considered greater than what would be expected. The contributions to permittivity from volume, contrast and interactions are separated. Theoretical models are applied in the study of permittivity and electrical conductivity. The poor predictions of classical models for permittivity are attributed to the positive behaviour of the permittivity change on mixing for these nanofluids. The contributions to electrical conductivity from water and nanoparticles are separated.
Descrição
Palavras-chave
Copper oxide Electrical conductivity Nanofluids Nanoparticles Relative permittivity Ethylene glycol
Contexto Educativo
Citação
M.F. Coelho, M.A. Rivas, G. Vilão, E.M. Nogueira, T.P. Iglesias, Permittivity and electrical conductivity of copper oxide nanofluid (12 nm) in water at different temperatures, The Journal of Chemical Thermodynamics, Volume 132, 2019, Pages 164-173, ISSN 0021-9614, https://doi.org/10.1016/j.jct.2018.12.025