Solar powered atmospheric water harvesting with enhanced LiCl /MgSO4/ACF composite

Abstract

Air humidity, as a source of water, is more or less available everywhere. The sorption capacity of water is a significant factor for the efficiency of atmospheric water harvesting (AWH) systems, which are based on the adsorption phenomenon. Lithium chloride has a high water-uptake rate, but has a very low delinquency relative humidity (DRH). Therefore, a host is required to make a stable composite. Composite of activated carbon fiber (ACF) and lithium chloride can keep the adsorbent immobile even after the occurrence of deliquescence, which also causes the three-phase sorption. However, the amount of salt inside the composite is limited by the prevention of leakage. In this paper, a binary salt composite is produced by a new method in order to enhance the water sorption capacity in terms of volume, and mass and the prevention the leakage. The effect of adding MgSO4 to the composite has been experimentally investigated for at different levels of relative humidity. The results showed that sorption capacity per unit volume and mass can be improved by the two-stage addition of MgSO4 without leaking in the adsorbent, reaching 0.78 g water/cm3 and 2.29 gwater/gadsorbent. The prototype made by the selected composite showed that AWH energy intensity was lower at higher relative humidity. The device was tested successfully in an arid climate and produced 0.92 gwater/gadsorbent when maximum RH reached 35% during the adsorption process.