Silica gel-based adsorption cooling cum desalination system: Focus on brine salinity, operating pressure, and its effect on performance

Abstract

In this study, a prototype of an adsorption desalination (AD) system was designed and manufactured using commercially available alumina silica gel to evaluate and improve its performance. To develop the AD system, the thermophysical properties of the adsorbent were first investigated based on adsorption isotherms of nitrogen and water vapor on the adsorbent; thereby, its applicability as a candidate adsorbent was verified. The performance of the AD system was then evaluated for different types of brine feeders in the evaporator (i.e., perforated plate and spray nozzles) using tap water as a feed over a wide range of key operating conditions such as hot-, cooling-, and chilled-water temperatures. Moreover, the performance of the AD process was assessed to verify the desalination mechanism and consistent desalting performance of the AD process; the process recovered more freshwater from seawater than conventional desalination technologies. The performance of the AD system was demonstrated to be independent of the brine concentration of the evaporator; moreover, the chemical quality of the freshwater recovered was revealed to be comparable to that of deionized water. Spray assisted evaporation exhibited high water vapor uptake owing to the effect of pressurization during the adsorption process, and hence, exhibited remarkable performance.