Spray cooling offers significant potential for applications requiring rapid and uniform solidification, such as in biological materials, yet the underlying transport phenomena are not fully understood. This study presents a comprehensive numerical and experimental investigation into the spray cooling process on a high-moisture, phase-changing substrate. A multiscale model was developed, coupling spray dynamics, wall-film phase-change heat transfer, and substrate solidification. An experimental system using R410A refrigerant was also constructed to validate simulations and investigate key parameters. The results reveal a strong correlation between spray parameters (distance, pressure) and the hydrodynamics of the surface liquid film. An optimal parameter window (25 mm distance, 1.6 MPa pressure) exists where atomization and droplet momentum create a thin, rapidly moving film, maximizing heat transfer. Furthermore, an intermittent spray strategy was proposed and proven superior to continuous spraying. By controlling the duty cycle (optimal at 0.83), the accumulation of an insulating liquid film was prevented, promoting efficient boiling and achieving the fastest solidification rate. This work elucidates the governing mechanisms of spray cooling on phase-changing substrates and provides a quantitative framework for process optimization.

Computational fluid dynamics (CFD), Heat transfer, Intermittent spray, Liquid film, Multiphase flow, Parameter optimization, Spray cooling