Effect of adsorption isotherm and kinetics on the performance of silica gel-based adsorption desalination system with heat and mass recovery

The equilibrium adsorption isotherm and adsorption kinetics are crucial factors affecting the performance and thermal efficiency of adsorption desalination (AD). To comprehensively evaluate the two crucial factors affecting the behavior of the AD cycle, an experimental investigation of the AD cycle was performed using two silica gels (GEL200 and NS10), and their effects were thoroughly analyzed based on the thermophysical properties of the adsorbents. It was found that the AD cycle using GEL200 with high net equilibrium adsorption capacity outperformed the cycle using NS10 with high thermal conductivity and adsorption kinetics. At a heat source of 85 °C, both specific daily water production (SDWP) and performance ratio (PR) of GEL200 were 40 % and 33 % higher than NS10, respectively. It was notable that the SDWP was predominantly influenced by adsorption isotherms rather than adsorption kinetics. To further improve SDWP and PR, heat and mass recovery were implemented. The maximum improvements in SDWP and PR with heat and mass recovery were 14 % and 23 % for GEL200 and 9 % and 38 % for NS10 compared to those without recovery. Here, the greater PR improvement achieved with NS10 was attributed to its superior thermal conductivity compared to GEL200.