Direct contact condensation of vapor bubbles in subcooled liquids: a review of dynamics, heat transfer, and interactions of bubbles

Direct contact condensation (DCC) of vapor bubbles in subcooled liquid is an efficient heat and mass transfer process, contributing significantly to industrial energy efficiency and sustainable energy utilization. This review synthesizes recent advances in the field. Beginning with fundamental theory, the physical nature of condensation is clarified, including bubble force balance and interfacial heat and mass transfer. Subsequently advanced experimental and numerical methods for capturing transient interfacial evolution and flow characteristics are critically assessed. On this basis, the dynamics and condensation mechanisms in both single-bubble and multi-bubble systems are analyzed. From an applied perspective, the influence of bubble interactions on interface distribution and flow structures is discussed, along with their implications for heat transfer efficiency and operational stability in practical devices. Although considerable progress has been made in elucidating macroscopic dynamics and average heat transfer behavior, clear gaps remain. They concern microscopic interfacial physics, high-resolution measurement of interfacial evolution, and predictive capability for multi-bubble and bubble-cluster dynamics under complex non-equilibrium conditions. Future efforts are suggested to prioritize elucidating microscopic interfacial evolution mechanisms and developing active control strategies for bubble clusters, thereby fostering innovation and performance enhancement of DCC technology in sustainable energy systems.