Experimental investigations of stability, density, thermal conductivity, and electrical conductivity of solar glycol-amine-functionalized graphene and MWCNT-based hybrid nanofluids

Abstract

This research article discusses properties such as density, thermal conductivity, and electrical conductivity of solar glycol with amine-functionalized graphene and multi-walled carbon nanotubes (MWCNTs). The hybrid nanofluid is prepared by dispersing the amine-functionalized graphene (AFG) and MWCNTs (50:50 in % by weight ratio) in pure solar glycol. The AFG and MWCNTs are dispersed in different volume concentrations of 0.05%, 0.1%, and 0.15% through the classical two-step homogenizing technique. Good colloidal stability nanofluid are prepared with Gum Arabic (non-covalent) as the surfactant. The stability of nanofluids is ensured through scanning electron microscopy, UV-Vis spectrometer, and zeta potential analyzer. The nanofluid thermal conductivity is measured with varying the nanomaterial loading from 0.05 to 0.15 vol% using a KD2 pro thermal analyzer. The thermal conductivity and electrical conductivity of nanofluid augmentations are considerably with an increasing volume concentration of AFG and MWCNT loading. The thermal conductivity of the AFG-MWCNT-based hybrid nanofluid is augmented by 8.59% for the maximum concentration of 0.15 vol% at 50 °C. The electrical conductivity of the solar glycol-based nanofluids is enhanced linearly with increased operating temperatures. The maximum electrical conductivity enhancement attained is ~28.85% at a nanoparticle loading of 0.15 vol% and 70 °C.

Keywords: Amine-functionalized graphene; Electrical conductivity; Gum Arabic; Multi-walled carbon nanotubes; Solar glycol; Thermal conductivity.