Dynamics-informed heat-transfer assessment of ethanol droplet impact on superheated surfaces

Ethanol droplet impact on superheated surfaces involves strong coupling between inertial deformation, vapour generation, rebound dynamics, and transient heat transfer. In this study, single ethanol droplets were impacted on a heated silicon surface over a broad range of impact inertia and surface temperatures. Four characteristic impact morphologies were identified, including boiling spreading, recoiling splashing, rebound, and elongated rebound. Quantitative analysis showed that maximum spreading remained primarily controlled by impact inertia, whereas detachment and rebound dynamics were more sensitive to thermal forcing and regime transition. A temperature-corrected spreading correlation reduced the mean absolute percentage error to 6.0%. The experimentally measured spreading and event-time quantities were then used as inputs to a dynamics-informed reduced-order thermal framework, while the resulting thermal-response quantities were model-derived rather than directly measured. The analysis showed that the thermal response is governed by the combined evolution of spreading geometry, interaction time, and vapour-film resistance rather than by surface temperature alone. For the screened vapour-supported conditions, the model-estimated film-boiling energy ranged from 11.73 to 38.92 mJ, corresponding to a mass-specific energy of 2.44– 8.09 kJ k g − 1 . These results establish a physically interpretable link between experimentally observed impact dynamics and reduced-order thermal response on superheated surfaces.