Design and transport properties of (ethylene glycol + water) - based nanofluids containing graphene nanoplatelets

Abstract

In this work, stable homogeneous nanofluids were designed as dispersions of sulfonic acid-functionalized graphene nanoplatelets in an (ethylene glycol + water) mixture at (10:90)% mass ratio and nanoparticle mass concentrations up to 0.5 wt.%. Nanofluid stability was evaluated by means of Dynamic Light Scattering (DLS) and Zeta Potential measurements. The thermal conductivity and dynamic viscosity of base fluid and nanofluids were experimentally obtained in the temperature range from (283.15 to 343.15) K by using a TPS 2500S Hot Disk and an AR-G2 rotational rheometer, respectively. Thermal conductivity improvements reach up to 5% while the maximum dynamic viscosity increase is 12.6%. Finally, the experimental values of these two transport properties were also utilized to analyze nanoparticle concentration effect on heat transfer performance and pumping power through different figures of merit.