Performance enhancement of a small solar desalination still with active solar tracking, spray evaporation, and auxiliary electrical heating

This study combines theoretical and experimental analysis of a solar/electric hybrid seawater desalination still with a spray-assisted evaporation device and a solar tracking system. A droplet-based model was developed to describe spraying, and evaporation within the vaporization tower. Reducing the nozzle aperture increases spray velocity and droplet fragmentation, enhancing the gas–liquid interfacial area, improving vaporization, increasing distilled water production, shortening production starting time, and improving energy efficiency. Experimental results agree well with theoretical predictions. The effects of electric heater power, solar input, and seawater salinity were investigated. Higher heater power provides diminishing efficiency gains due to heat losses, while higher salinity reduces distilled water production due to lower vapor pressure and elevated boiling point. Heat transfer analysis also indicates that dynamically adjusting the electric heater power based on the quality of the vaporization tower and solar radiation energy, while controlling the vaporization tower operation in the saturation region, can achieve stable operation, improve efficiency, and reduce operating costs.