Subcooled flow boiling bubble dynamics: Surface tension-optimized force balance model and experimental validation

Subcooled flow boiling plays a critical role in thermal management systems for nuclear reactors and high-power industrial boilers, where accurate prediction of bubble dynamics remains challenging for conventional models. This study presents an enhanced force balance model that significantly improves boiling process prediction through two key refinements: 1) comprehensive incorporation of surface tension effects via additional pressure analysis, and 2) physics-based determination of bubble contact diameter using a shape factor derived from Weber number relationships. Experimental validation was conducted through visualized subcooled boiling experiments on zirconium surface, employing high-speed imaging and advanced image processing to quantify bubble detachment characteristics (diameter: 0.7–4 mm, time: 7–100 ms) and sliding velocities (0.1–0.8 m/s). The improved model demonstrates superior agreement with experimental data, reducing prediction errors for detachment diameter compared to conventional approaches. These advancements provide critical theoretical support for optimizing boiling system design and safety assessment, particularly in nuclear energy applications where precise bubble behavior prediction is essential for accident prevention and thermal efficiency enhancement. The proposed methodology establishes a new framework for multiscale boiling analysis with improved physical fidelity. © 2025 Elsevier Masson SAS.