Thermocapillary Convection Flow and Heat Transfer Characteristics of Graphene Nanoplatelet Based Nanofluid Under Microgravity

In view of the high thermal conductivity of graphene, adding graphene to silicone oil to form nanofluids is expected to enhance thermocapillary convection and the efficiency of heat transfer under the microgravity conditions. In the present study, graphene nanofluid thermocapillary convection in a two-dimensional rectangular cavity was investigated numerically, in which the two-phase mixture model was used to simulate the nanoparticles-fluid mixture flow, the influences of volume fraction of nanoparticles and cavity aspect ratio on the flow characteristics and heat transfer performance were discussed. The results show that with the volume fraction of graphene increases, thermocapillary convection intensity decreases at both ends of the cavity, and the thermocapillary convection in the central cavity increases first and then weakens; meanwhile, the temperature gradient of free surface at both ends of the cavity increases, and the free surface velocity increases first and then decreases with increasing volume fraction of graphene. The intensity of thermocapillary convection to be increased to the maximal value at α p of 3 vol% and then reduced. The peak heat flux on the hot wall of the cavity gradually shifts from the upper part to the lower part with increasing volume fraction of graphene, meanwhile, and the Nusselt number of the hot wall surface of the cavity gradually decreases. Thermocapillary convective heat transfer intensity of the cavity hot wall increases with the decrease of the aspect ratio.