Experimental evaluation of a solar-driven adsorption desalination system using solid adsorbent of silica gel and hydrogel

Nowadays, the world is facing a shortage of fresh water. Utilizing adsorbent materials to adsorb air moisture is a suitable method for producing freshwater, especially combining the adsorption desalination system with solar energy devices such as solar collectors. The low temperature of solar collectors has caused some water to remain in the adsorbents in the desorption process and has reduced the possibility of using these systems. In this research, for the first time, an evacuated tube collector (ETC) is used as an adsorbent bed so that the temperature of the desorption process reaches higher values and as a result, more fresh water is expected to produced. In this study, two adsorption desalination systems (ADS) are experimentally investigated. In the first system, a laboratory experimental setup using silica gel and hydrogel adsorbents is used to investigate freshwater production using each of the two adsorbents. The effect of different parameters such as variable adsorption and desorption time, variable temperature and humidity of inlet air, and variable adsorbent mesh sizes on the desalination process is evaluated. Then, in the second system, an innovative configuration of the solar-driven adsorption desalination system with an ETC full of silica gel is studied. In the laboratory experimental setup, the maximum amount of water produced by silica gel is 0.36 L/kg and by hydrogel is 0.58 L/kg. In the solar-driven adsorption desalination system, the largest amount of accumulated water production, daily efficiency, and cost per liter (CPL) of produced water are 1.518 kg/m(2) day, 11.25%, and 0.0699 $/L, respectively. Therefore, this new configuration for an adsorption desalination system seems feasible.