Numerical investigation of vapor bubble condensation in subcooled quiescent water

Abstract

The vapor bubble condensation process is numerically investigated via three-dimensional (3D) simulation using Volume of Fluid method (VoF). Two phase change models, i.e. Lee model and Tanasawa model, are implemented and assessed with experimental data. Since no mesh-independent results can be obtained with the Lee model, the Tanasawa model is adopted for the study of bubble condensation process. The single vapor bubble condensation in subcooled quiescent water is analyzed. Different influencing factors on bubble condensation, i.e. diameter size, subcooling and liquid properties, are studied. With the increase of the bubble diameter, the condensation rate increases due to increase of the shear stress between the vapor bubble and the cold bulk, resulting in the turbulence inside the bubble being more intensive and the thermal field around the bubble more unstable. High subcooling increases the mass flux across the interface, which brings about the interface instability on the bubble surface and bubble breakup is observed. The increase of the liquid viscosity restricts the bubble rising and deformation, which reduces the convective heat transfer and condensation rate. The occurrence of bubble central breakup due to the decrease of surface tension enlarges the effective condensation area and increases the condensation rate.