Performance enhancement of electrodialysis regeneration of deep eutectic solvent for liquid desiccant air conditioning systems

Abstract

Despite the promising energy-saving potential of the electrodialysis regeneration technique for liquid desiccant regeneration in air conditioning systems, there are still issues that need to be resolved in electrodialysis separation systems, such as the high initial cost owing to the complexity of the cell gaps, over-limiting current, and electro-osmotic flow effects. This study utilized stereolithography (SLA) 3-D printing technology to manufacture a low-cost scalable model of an electrodialysis system. An electrodialysis system with a cell gap of 5 mm and serpentine flow feed spacers was investigated to regenerate deep eutectic solvent (DES) developed from choline chloride and ethylene glycol as a bio-friendly liquid desiccant for air conditioning systems. Ammonium chloride electrode rinsing solution with about 250 mS/cm electric conductivity was utilized to enhance the conductive properties of the system. The optimum parametric operating conditions for the system are found to be around 0.0058 m/s for the circulation flow rate, 0–4 wt.% for the concentration difference of the diluted and regenerated solutions' cells, and 6–8 V voltage supply energy input. In 60 minutes of operation, the current efficiency value of the constructed model was discovered to be as high as 65.82%. Matching the performance threshold of the commercial electrodialysis equipment described in the literature for regenerating lithium chloride conventional liquid desiccant.