Performance analysis of a lab-scale adsorption desalination system using silica gel/LiCl composite

Abstract

Adsorption desalination is a novel technology to supply high-quality potable water driven by a low-temperature heat source. However, only a few composite sorbents, whose excellent performances have been demonstrated in other adsorption-based systems, have been applied in adsorption desalination (AD) systems. This study evaluated the performances of LiCl-silica gel (30 % wt) composite in a lab-scale AD system, realized by packing the sorbents beads inside a finned flat-tube heat exchanger. For the first time, the ad/desorption dynamics under various operating conditions were measured using a T-LTJ (thermal-large temperature jump) apparatus, which has not been employed for evaluation of desalination prototypes so far. The sorption dynamics was compared with silica gel, which is a standard material for AD systems. Results were used to calculate the maximum specific daily water production (SDWP) and optimized cycle time. Moreover, three design strategies of the AD system were proposed, including 2-beds, 3-beds and 4-beds. The 3-beds-configuration was selected for the composite sorbent, being able to reach an SDWP as high as 69 m3/tonne/day under the condition of Teva/cond = 20 °C and Tde = 80 °C. The optimized cycle time is dependent on operating conditions, varying in the range of 240–470 s.