Numerical Modeling of Multiple Bubbles Condensation in Subcooled Flow Boiling

Abstract

The understanding of multiple bubbles condensation is of significant importance in developing continuum models for the large-scale subcooled flow boiling. The computational fluid dynamics (CFD) modeling for multiple bubbles condensation is developed with the volume of fluid (VOF) method in this work. An explicit transient simulation is performed to solve the governing equations including the source terms for heat and mass transfer due to condensation. The geometric reconstruction scheme, which is a piecewise linear interface calculation (PLIC) method, is employed to keep the interface sharp. The surface tension is modeled by the continuum surface force (CSF) approach, which is taken into account in the numerical model. Numerical simulations predict the dynamical behavior of the actual condensing bubbles. The results show that the condensation rate of a single bubble is influenced by the velocity of the fluid flow and the temperature difference between the bubble and fluid. For multiple bubbles, the effect of bubble–bubble interaction on their condensation process is analyzed based on the numerical predictions. The condensation rate of lower bubbles increases due to the random perturbation induced by other bubbles. The influence of other bubbles on the condensation rate can be neglected if the distances between the bubbles are large enough.