Effects of Nanoparticle Shapes on Heat and Mass Transfer of Nanofluid Thermocapillary Convection around a Gas Bubble

Abstract

In order to reveal the influence of nanoparticle shape on heat transfer in nanofluid nucleate boiling process, a three-dimensional numerical investigation of nanofluid thermocapillary convection around a gas bubble is conducted. Five different shaped nanoparticles are used in this study and the nanofluid flow is simulated by two-phase mixture model. The thermocapillary convection intensity of nanofluid with spherical nanoparticles is the largest, which is followed by blade, brick, cylinder and platelet shapes, respectively. Non-spherical nanoparticles with a suitable shape and relatively high volume fraction are beneficial for heat transfer enhancement, and nanofluid containing blade shaped nanoparticles has the largest heat transfer enhancement, which is followed by platelet, cylinder and blade shapes respectively. In particular, as αp = 0.05 the average Nusselt number of nanofluid with blade, platelet, cylinder and blade shaped nanoparticles are increased by 22.8%, 11.7%, 7.7% and 2.8% relative to that of with spherical nanoparticle respectively. Moreover, the total entropy generation increases with nanoparticle sphericity increasing.