From condensation to mature frost growth-an advanced model to predict surface wettability and edge effects on frosting

Frost formation and its accumulation on a surface is a critical phase-change phenomenon in cold and humid environments, with surface properties playing a pivotal role in this process. While most existing models focus on the prediction of frost accumulation during the mature growth stage, with a simplified assumption of uniform initial ice layer as the initial condition, the effects of surface wettability and edge geometry on early-stage ice propagation and initial frost layer formation have been largely neglected and not been fully incorporated in a complete frost growth prediction but highly relevant to heat exchanger design. In this study, a new model is developed to enable a more comprehensive representation of frost evolution by integrating droplet condensation, droplet freezing, and ice propagation - the initial ice layer formation as the initial condition to the frost growth prediction, which allows a precise prediction of surface properties (wettability and geometry, edges) effects on frost layer growth. Experimental validation was carried out in a controlled wind tunnel environment across surfaces of varying wettability and sizes. The results demonstrated that edge effects led to accelerated droplet growth at surface boundaries during condensation process, while hydrophobic surfaces effectively delayed frost growth by reducing ice propagation speed. The model's integration of ice propagation not only predicted the surface freezing time accurately but also enhanced the representation of hydraulic and thermal boundary layers. These findings highlight the critical role of edge effects and surface wettability in frost growth modeling, providing valuable insights for designing ice-resistant surfaces in cold and humid environments. • A frost growth model simulates both initial ice propagation and mature frost. • Edge effects accelerate droplet growth, creating nonuniform frost distribution. • Hydrophobicity slows ice propagation, delaying freezing by up to 2.4 times. • Surface length increases freezing time and frost thickness up to 94.3%.