Thermal conductivity and specific heat capacity of water-ethylene glycol mixture-based nanofluids with graphene nanoplatelets

In the present work, we report the thermal conductivity and specific heat capacity of water-ethylene glycol mixture with graphene nanoplatelets inclusions. Stable nanofluid dispersions were prepared with sodium deoxycholate as the surfactant. Stability of nanofluids was characterized by optical absorption spectroscopy and zeta potential analysis. Thermal conductivity of nanofluids was found to increase with respect to nanoplatelets loading, while the specific heat capacity was decreasing. Highest enhancement in thermal conductivity of nanofluid was found to be similar to 18% at 0.45 vol% of nanoplatelets loading while at the same concentration the specific heat capacity was similar to 8% lower. Further measured thermal conductivity was compared with effective medium theory calculations considering the role of interfacial thermal resistance. From the model calculations, we show that the interfacial thermal resistance between graphene nanoplatelets and water-ethylene glycol mixture was significantly high in the order of 1.7 x 10(-8) m(2) K W-1 which limits the thermal conductivity enhancement despite the high intrinsic thermal conductivity of graphene nanoplatelets.