Experimental investigation of modified solar still coupled with high-frequency ultrasonic vaporizer and phase change material capsules

In present study, the effect of combining single-slope solar still unit with high-frequency ultrasonic vaporizer, PCM capsules, and external solar water heater on improving its performance was experimentally investigated. A single-slop solar still was developed and examined under the harsh climate of Baghdad city in middle Iraq territory. Compared with the conventional solar still, the results indicated that using PCM cylindrical capsules increases the water productivity of the still about 30.6%. High water productivity was achieved by using an external solar water heater and high-frequency ultrasonic vaporizer was about 415% respectively. Results also illustrate that increasing the operation time of ultrasonic vaporizer has a negative effect on water productivity and thermal efficiency. The maximum thermal efficiency reached 39.3% for the modified solar still with ultrasonic vaporizer with 30 min operation time, while its value is reported to be about 34.2% for 60 min operation time. According to the economic analysis, such units are reliable in remote regions with an estimated cost equal 0.037 and 0.028 $/L for conventional and modified solar still with ultrasonic vaporizer respectively.