Molecular dynamics simulation on LiCl-H2O interfacial phenomenon for liquid desiccant dehumidification

Abstract

In this paper, molecular dynamics simulation was conducted to analyze the air-solution interface phenomenon of LiCl-H2O for liquid desiccant air dehumidification. Density profiles of ions in liquid desiccant aqueous solutions were plotted along the z axis, and distribution preferences of ions on the air-solution interface were studied. Besides, vapor pressure profiles above the solution surface were plotted, and the saturated vapor pressure was predicted and compared with the empirical data. It was found that water density remained stable in the bulk, and there was a sharp decrease on the air-solution interface. For the ions (Li+ and Cl-), a density peak was observed on the interface, which indicated that ions preferred to appear on the interface rather than in the bulk. When the system temperature was relatively lower, the chloride ions had more preference to exist on the interface than lithium ions. However, when the system temperature reached as high as 350 K, chloride ions and lithium ions had almost the same preference. When the system temperature was 300 K, simulation data of vapor pressure matched well with the empirical data. With the increase of the system temperature, the deviations became larger while the variation tendencies were the same.