Membrane distillation to regenerate different liquid desiccant solutions for air conditioning

• Published in: Desalination Vol. 443; pp. 137 - 142
• Main Authors: Duong, Hung C., Álvarez, Iván R.C., Nguyen, Tinh V., Nghiem, Long D.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2018
• Subjects: Liquid desiccant air-conditioner (LDAC); Liquid desiccant regeneration; Membrane distillation (MD); Mixed liquid desiccant solutions; Liquid desiccant regeneration; Liquid desiccant air-conditioner (LDAC); Membrane distillation (MD); Mixed liquid desiccant solutions
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2018.05.023

The capacity of membrane distillation (MD) to regenerate three commonly used liquid desiccant solutions (i.e. CaCl2, LiCl, and a mixture of CaCl2/LiCl) for liquid desiccant air-conditioners (LDAC) was evaluated. The results demonstrate considerable impact of the concentration polarisation effect on the process water flux during MD regeneration of these three desiccant solutions. For each of these liquid desiccant solutions, the experimentally measured water flux of the MD process was about half of the calculated value using the process mass transfer coefficient (Km) obtained during the process characterisation without taking into account the concentration polarisation effect. The observed deviation between the experimentally measured and calculated process water flux indicates the need to include the concentration polarisation effect in the model for calculating water flux. Although Ca2+ concentration in the CaCl2 and CaCl2/LiCl liquid desiccant solutions exceeded the solubility limit for CaCO3, membrane scaling was not observed. Nevertheless, there was evidence that membrane fouling might occur during extended MD regeneration of liquid desiccant solutions containing CaCl2. •LiCl, CaCl2 and mixed CaCl2/LiCl liquid desiccant solutions were generated by MD.•Regeneration rate was inversely proportional to their dehumidification capacity.•Concentration polarisation effect was significant due to high salt concentrations.•Membrane scaling was not observed during MD regeneration of the desiccant solutions.