Seawater desalination using Dewvaporation technique: experimental and enhancement work with economic analysis

This paper presents experimental data using Dewvaporation towers. The data was collected as a function of temperature and then compared against the theory for both brackish (1000 ppm) and sea waters (42,000 ppm). Based on experimental data, an overall heat transfer coefficient was determined. It was concluded that the effective heat transfer area was 25% of the total 7.9 m2 (85 ft2) with hg = 15.3 W/m2) K (2.7 Btu/h.ft2°F). This reduction was proven, using flow visualization experiments, to be the result of the unbalanced air streamlines on either side of the heat transfer wall. The purity of the distillate was less than 500 ppm for 42,000 ppm feed. A desiccant heat exchanger was proposed as a potential enhancement technique for energy consumption in the Dewvaporation operation. Mathematical modeling showed that the energy reuse factor could be improved by a factor of 3/2 using desiccant heat exchanger. Nevertheless, initial experimental data provided support for the desiccant concept. Finally, economics analysis was performed based on 3.8 m3/d (1000 gal/d) production for different designs. Capital cost ranged from $1646 to $2814 and operating cost per day ranged from $3.82 to $3.43.