Mechanistic modeling and parameter screening of ultrasonic oscillation-assisted seawater falling-film evaporation on a flat plate

To overcome limited heat and mass transfer and scaling during low-temperature seawater desalination, this study develops a one-dimensional model of ultrasonically assisted plate falling-film seawater evaporation. Predicted outlet brine temperatures and evaporation rates show mean percentage errors below 5% against published pure-water falling-film data. The salinity-correction model agrees well with reported data, while the cavitation threshold shows a mean absolute deviation below 6.47%. The responses to ultrasound power, salinity, flow velocity, and frequency are also consistent with reported trends. Increasing the inclination angle from 0° to 45°increases total water production and the effective flow path by 41% and 42%, respectively, despite a 1.0% reduction in the mean evaporation flux. The higher water yield arises from a longer flow path, extended residence time, and larger effective evaporation area. Raising ultrasound power from 0 to 600 W increases total water production and mean evaporation flux by 101.5% and 115%, respectively. Frequency exerts a non-monotonic effect on evaporation, with stronger enhancement at 20-32 kHz. Changing the oscillator position produces peak-valley responses, and a normalized position of 0.65-0.72 yields better performance. Increasing the system pressure from 30 to 101.325 kPa reduces total water production and mean evaporation flux by approximately 81% and 84%, respectively. These findings provide a model-based basis for prioritizing structural and operating parameters and for guiding future optimization and validation of ultrasonic-assisted flat-plate falling-film evaporators.