Evaluation of Electrodialysis-Liquid Desiccant and Vacuum-Membrane Dehumidification Systems for High-Efficiency Cooling

Abstract Separate sensible and latent cooling (SSLC) systems are a low-energy, sustainable solution to conventional vapor compression systems (VCS) for space cooling. These systems also eliminate synthetic refrigerants with high global warming potential. In this paper, we analyze two electrically-driven dehumidification systems using a first-principles-based thermodynamic simulation: i) a hybrid electrodialysis–liquid desiccant (ED-LD) system combining LD dehumidification and ED regeneration, and ii) a vacuum membrane dehumidification (VMD) system. In both systems, a dew point evaporative cooler is used for sensible cooling before the final supply of cooled air. We estimate that the hybrid ED-LD system can reduce the energy requirement by up to 85% compared to a state-of-the-art VCS in hot and dry climates. However, as ambient humidity increases, the energy needed to regenerate the LD solution rises drastically, and the performance of the ED-LD system decreases. The VMD system uses water vapor-selective hydrophilic membranes to remove moisture from air. We show that it can reduce the power consumption by 15-91% compared to a VCS in different ambient conditions. A higher ambient wet bulb temperature increases the total power requirement of VMD systems as the solubility of the water vapor in the regenerator increases, creating a higher resistance for removing moisture from the system. Overall, these hybrid systems show promising potential to save energy in buildings, but they must be carefully analyzed to assess the feasible operating conditions and system configurations for maximum energy savings.