Parametric study of low-temperature solar-assisted flash evaporation desalination systems using two-phase water–steam ejector

This study aims to investigate a two-phase subsonic ejector added to a flash evaporation desalination system to increase the system productivity of distilled water. The flash evaporation was of low-temperature condition that it could be powered by a flat and evacuated tube solar water heater. A parametric study of superheat degree (range 5°C–25°C), back pressure (range 10–30 kPa of absolute pressure), primary fluid flow rate (range 1–3 L/min), nozzle diameter (range 1–3 mm), and salinity concentration (range 0%–7%) were investigated to examine the system productivity and the ejector performance in terms of its entertainment ratio under different operating conditions. Results show that the inclusion of the ejector led to an average of 99% improvement in system productivity, primarily through the efficient secondary flow. Moreover, the effect of the studied parameter was more pronounced in the considered flash evaporation desalination system as it has two places where flash evaporation occurs, compared with the normal system where the flash evaporation occurs at one place. All in all, the application of the ejector could enhance the system's productivity significantly under different operating conditions.