▎ 摘　　要

Nanofluids-suspensions of nanomaterials in conventional fluids-have demonstrated great potential for improving the heat transfer properties of liquid. In particular, graphene nanosheets (GNS) attracted much attention recently due to its high thermal conductivity. In this work, GNS-ethanol nanofluids were prepared from exfoliated graphite with varying volume fractions (0.02-0.1 vol%). The thermal conductivity and viscosity of GNS nanofluids were measured and analyzed as a function of the volume faction and temperature. The outstanding thermal conductivity enhancement was obtained due to the suspension of GNS. The thermal conductivity enhancement would reach similar to 10% with 0.1 vol% GNS dispersion. To investigate the heat transfer enhancement, numerical simulations of natural convection in a square enclosure with GNS nanofluids were carried out. We found that the reason for the enhanced convection heat transfer of GNS nanofluid is the improvement of thermophysical properties. The convective heat transfer coefficient of GNS nanofluid is larger than that of the base fluid by approximately 12%. The excellent thermal performance of GNS nanofluid shows great potential in heat transfer applications.