SALINE WATER SPRAY CHARACTERIZATION IN A ROTARY INJECTOR FOR THERMAL DESALINATION PROCESS

Thermal desalination processes that extract fresh water from saline water often rely on the atomization of the saline water to achieve a high humidification rate. However, experimental studies on saline water sprays have received much less attention. In particular, the potential of rotary atomizers remains unexplored, despite their ability to achieve efficient atomization at high liquid feed rates. The current study evaluates the characteristics of saline water sprays in a rotary atomizer using optical diagnostics. The atomizer was tested across a broad range of rotational speeds, <i>N</i> (5000-20,000 rpm) and liquid feed rates, <i>Q<sub>l</sub> </i>(6 L/h and 12 L/h). Experiments were conducted with distilled water for comparison. The primary liquid breakup process near the injection orifices was visualized using the front light illumination technique, and droplet size was measured using Interferometric laser imaging for droplet sizing technique. Results indicate that the primary liquid breakup mode and droplet size are strongly influenced by the atomizer's rotational speed. The Sauter mean diameter (SMD) decreased from approximately 100 to 50 μm as <i>N</i> increased over the above range. Although the breakup mode was similar for both saline and distilled water, SMD was about 10% smaller for saline water, at higher rotational speeds. This could be explained using a theoretical model. The current experiments also demonstrate the ability of the rotary atomizer to achieve similar droplet sizes across a wide range of liquid feed rates.