Three-dimensional numerical simulation of successive bubble condensation in mini-channels with VOSET method

Abstract

In this paper, based on the energy jump model, the VOSET method is applied to study the condensation dynamics and heat transfer characteristics of successive bubbles in a three-dimensional mini-channel. The effects of liquid subcooling, inlet velocity distribution, initial bubble diameter, and bubble release interval are systematically examined. Successive-bubble condensation is governed by a competition among hydrodynamic enhancement, wake weakening, and coalescence confinement. Increasing the fluid subcooling strengthens the interfacial condensation driving force and accelerates interface recession relative to wake-induced bubble chasing, which increases the inter-bubble spacing and reduces repeated coalescence. At sufficiently high subcooling, the cumulative average volumetric condensation rate exhibits diminishing sensitivity to further increases in liquid subcooling. Nonuniform inlet velocity distributions generate asymmetric hydrodynamic forces, causing lateral migration and shifting the main mass transfer location toward the upwind side. Nevertheless, relative to the uniform-inlet case, the mean relative deviations in total bubble volume are only 0.59% and 3.07% for the linear and sinusoidal velocity distributions. As the initial bubble diameter increases, the mass transfer rate per unit area initially increases due to enhanced flow perturbations. However, repeated coalescence and channel confinement suppress mass transfer at later times. Longer bubble release intervals increase the initial inter-bubble spacing, weaken wake interactions and coalescence, and promote nearly independent bubble condensation.