Analysis of Heat Transfer Characteristics of a GnP Aqueous Nanofluid through a Double-Tube Heat Exchanger

Abstract

The thermal properties of graphene have proved to be exceptional and are partly maintained in its multi-layered form, graphene nanoplatelets (GnP). Since these carbon-based nanostructures are hydrophobic, functionalization is needed in order to assess their long-term stability in aqueous suspensions. In this study, the convective heat transfer performance of a polycarboxylate chemically modified GnP dispersion in water at 0.50 wt% is experimentally analyzed. After designing the nanofluid, dynamic viscosity, thermal conductivity, isobaric heat capacity and density are measured using rotational rheometry, the transient hot-wire technique, differential scanning calorimetry and vibrating U-tube methods, respectively, in a wide temperature range. The whole analysis of thermophysical and rheological properties is validated by two laboratories. Afterward, an experimental facility is used to evaluate the heat transfer performance in a turbulent regime. Convective heat transfer coefficients are obtained using the thermal resistances method, reaching enhancements for the nanofluid of up to 13%. The reported improvements are achieved without clear enhancements in the nanofluid thermal conductivity. Finally, dimensionless analyses are carried out by employing the Nusselt and Péclet numbers and Darcy friction factor.

Thermophysical Properties of Nanocolloids and Their Potential Applications

“…Several articles were received, and with the help of our experienced reviewers, 10 papers were selected for publication [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ]. From a statistical data perspective, the reader should note that the articles had already received 29 citations and 9243 visualizations at the time of the writing of this Editorial.…”

“…The first article originates from University of Vigo and Institut für Luft-und Kältetechnik Dresden labs and is an experimental analysis of the heat transfer of nanofluids based on graphene nanoplatelets diluted in water [ 1 ]. The authors used an experimental facility to evaluate the heat transfer performance based on a turbulent regime, obtaining an enhancement of the nanofluid of up to 13%.…”