Thermal and Dielectric Performance of Ester Oil Based Pentyl-graphene Nanofluids

Abstract

The authors highly acknowledge Mr. Kevin Rapp (Senior scientist of Cargill) and Mrs. Sabine Bowers from Cargill for the FR3 oil supply during this research.

Dielectric and Thermal Response of TiO2 and SiC Natural Ester Based Nanofluids for Use in Power Transformers

“…Therefore, it is obvious that at this weight percentage, the integration of this type of NPs has led to significant thermal conductivity enhancement of the dielectric liquid. This finding is consistent with several published research works regarding the influence of nanometric scale particles in thermal conductivity [20,21,39,40,50]. The high thermal conductivity of the SiC NPs (165-220 W/(m•K)) with respect to TiO2 could be responsible for the higher improvement concerning the sNF sample [51,52].…”

“…It is clear from this graph that both NF samples have improved thermal diffusivity with respect to NEO, with sNF showing the higher improvement throughout the whole temperature range. Beyond that, as the temperature rises, all samples show a decrease in diffusivity [45,49,50]. The Matrix oil sample has the greatest impact on the thermal diffusivity behavior of NFs, as evidenced by the experimental results, as long the same trend in thermal diffusivity with temperature increase is also observed for the NFs [50].…”

“…The high thermal conductivity of the SiC NPs (165-220 W/(m•K)) with respect to TiO2 could be responsible for the higher improvement concerning the sNF sample [51,52]. Thermal behavior of the two NF samples at these concentration levels is directly affected from the NPs, since they do not suffer from rapid aggregation, as it has been shown in our previous works [13,17,50,53]. When NPs cluster, they lose their ability to increase heat transmission, alter the structural distribution of the suspension system, and ultimately break the irregular movement laws [52].…”

“…Beyond that, as the temperature rises, all samples show a decrease in diffusivity [45,49,50]. The Matrix oil sample has the greatest impact on the thermal diffusivity behavior of NFs, as evidenced by the experimental results, as long the same trend in thermal diffusivity with temperature increase is also observed for the NFs [50]. Figure 7 shows the thermal conductivity of the samples under investigation as a function of temperature.…”

“…It is also obvious that the dielectric constant falls with increasing temperature in all under-study samples, therefore they are more insulative with temperature rise. The temperature effect could be attributed to the fact that, dipolar orientation polarization processes taking place in this frequency range, are proportional to 1/T [50]. Assuming that this type of polarization is the main contributor to polarizability, the recorded dielectric constant reduction with temperature increase can be explained.…”