Performance optimization of polymeric porous membrane‑based liquid desiccant air dehumidifier used in air conditioning system

In this study an experimental design was developed to optimize the performance and structure of a membrane-based parallelplate liquid desiccant dehumidifier used in air conditioning regeneration system which operates under high humidity weather conditions. We conducted a series of polymeric porous membranes with different compositions fabricated that were prepared with various weight percentages of polysulfone (PSU), mixed with N-methyl-2-pyrrolidone (NMP) and dimethyl form amide (DMF) solvents. Furthermore, the designed experiments were performed under various operating conditions, indicating that the dehumidification efficiency declines with increasing flow rate, temperature, and humidity. Consequently, a membrane with optimized porosity and moisture permeability was selected which resulted in eliminating the carryover of solution droplets in the air, largely due to separating the flow condition of liquid desiccant (Li Cl) and air. This specific design is also greatly benefited by removing the water vapor from the air stream. The results of mathematical model simulations indicate that the DMF solvent had higher dehumidification capability compared with that of NMP under the optimized operating conditions. Additionally, it can clarify the porosity of the membrane which plays a significant role in the overall performance. Therefore, the fabricated membrane produces fresh cool air, and it can be applied as a guiding sample for designing the membrane-based dehumidifier with improved performance.