Synthesis and analysis of surfactant-assisted ethylene glycol-graphene nanofluid for use in heat transfer systems

With the possibility of reducing particle size to the nanometer scale, a new range of applications for heat transfer fluids (HTF) has emerged. Through dispersion of nanoparticles in a base fluid, a nanofluid is obtained, which exhibits significant improvements in thermophysical and heat transfer properties. However, achieving suspension stability of the nanoparticles requires considerable effort. This study aimed to prepare a nanofluid of ethylene glycol (EG) and commercial graphene (Gr-XP), using sodium dodecyl sulfate (SDS) as a surfactant. Nanoparticle concentrations of 0.010; 0.025; 0.050 and 0.100 wt% were tested, both without and with the surfactant at the ratios of 1:0.5; 1:1; 1:1.5 and 1:2. In order to investigate the effects of graphene and surfactant dispersed in ethylene glycol, Zeta potential, Dynamic Light Scattering (DLS), and visual observation were employed to assess the nanofluid stability. Thermal conductivity was evaluated between 25 and 50 °C using the Transient Hot Wire method. The stability of the nanofluid was achieved, with a 17.52 % increase in thermal conductivity for the nanofluid containing only 0.1 wt% at 50 °C. This represents a significant enhancement considering the low concentration, suggesting that the proposed nanofluid is a promising alternative HTF for vehicle cooling and energy conversion systems. • Easy and fast synthesis of nanofluids using ethylene glycol and commercial graphene. • Maximum amount of graphene: 0.1 wt%. • Wide variation of nanoparticle and surfactant levels to assess stability and conductivity.