Effect of saline-fog temperature and collection-duct height on fog-desalination effectiveness

Fresh water is vital for the continuation of human life, but unfortunately, the world is currently suffering from a severe shortage of fresh water sources. Recently, the use of fogging technique in desalination was introduced, and promising preliminary results have been reported. In this study, the effect of three operating and design pa-rameters: the vertical height of the horizontal duct (vapor extraction point), heat-exchanger inlet water tem-perature, and feed water salinity, on the product-water salinity is experimentally investigated. The following experimental conditions are applied: feed water salinities, 30,000 ppm and 10,000 ppm; vertical heights, 150 cm, and 235 cm; and heat-exchanger inlet water temperatures: 50 degrees C, 70 degrees C, and 90 degrees C besides no heating condition. The product-water salinity values reach 2874 ppm and 1028 ppm when the fog is generated without supple-mentary heating for the feed water salinity values of 30,000 ppm and 10,000 ppm, respectively. The process effectiveness is also explored, and the results show that the effectiveness is highly dependent on the operation mode and feed water salinity. The effectiveness values reach 91.33% and 92.49% when the fog is generated without supplementary heating for the feed water salinity values of 30,000 ppm and 10,000 ppm, respectively. It is worth mentioning that the salinity of the product water increases with the heat exchanger temperature. Additionally, the higher the horizontal collection duct, the lower the salinity of the product water. A mathe-matical model was developed and validated to describe the evaporation process of the droplet. The model showed good agreement with the experimental results.

Automated summary

Fresh water scarcity is a serious issue for human survival, but the introduction of fogging technique in desalination has shown promising results. This study investigates the impact of different parameters on product water salinity, and explores the effectiveness of the process. A mathematical model is developed and validated to describe the evaporation process of the droplet.