Study of Dynamic Moisture Adsorption and Desorption Performance of Thermosensitive Composite Adsorbents

With continuous economic development, the world faces a growing freshwater shortage and energy scarcity crisis. Reducing energy consumption in handling heat and moisture loads in air-conditioning systems and solving the global water crises have become urgent priorities. The dynamic adsorption and desorption properties of adsorbents significantly affect the heat and moisture transfer characteristics of adsorptive atmospheric water-harvesting systems and dehumidifying heat-exchanger air-conditioning systems. In this study, the dynamic adsorption and desorption properties of thermosensitive composites doped with different thermally conductive nanomaterials, such as nano-copper powder, nano-silver powder and nanographene, were investigated, and the theoretical daily water production capacity of the optimal materials was analyzed. The results show that the thermosensitive materials doped with graphene nanopowder have good adsorption/desorption kinetics. Their equilibrium adsorption capacity reaches 2.51 g/g, which is 1.46 times higher than the undoped thermally conductive materials. The desorption within 60 min is 1.17 times higher than undoped thermally conductive materials. In addition, with a cycle time of 3 h and an adsorption-to-desorption time ratio of 2∶1, the thermosensitive material doped with nanographene can achieve a theoretical daily water volume of 7.02 g/(g·d), which is 21% higher than that of the undoped material.