Lattice boltzmann simulation of boiling bubbles coalescence in Al₂O₃-water nanofluid

The coalescence process of bubbles is one of the most important factors for boiling heat transfer. In order to investigate the effects of factors on bubble coalescence in nanofluid, a lattice Boltzmann model is established. The model describes the coalescence processes of boiling bubbles by coupling liquid phase model and vapor phase model. The coalescence processes of boiling bubbles in Al₂O₃-water nanofluid and pure water are investigated based on the lattice Boltzmann method in this paper. The effects of distance between two bubble interfaces, interface thickness, migration rate, surface tension (nanoparticle mass fraction), and difference of bubble diameters on bubble coalescence processes are discussed in this paper. It is found that the velocity of bubbles coalescence in nanofluid is lower than that in pure water, which caused smaller bubbles in nanofluid compared with that in pure water. In addition, the boiling bubble sizes in pure water and Al₂O₃-water nanofluid are measured by an experimental method, and the same conclusion that the bubble sizes in nanofluid are smaller than that in pure water is obtained.