Saturated vapor pressure regulation mechanism of liquid desiccant material: to achieve air deep dehumidification

Air deep dehumidification plays an increasingly important role in the stable and efficient operation of high-end industrial production. Liquid dehumidification, as a highly promising method for air deep dehumidification, can enhance deep dehumidification performance by revealing the saturated vapor pressure regulation mechanism of liquid desiccant material. In this paper, the concept of saturated vapor pressure reduction rate (Dp) is introduced to quantitatively characterize the degree to which the saturated vapor pressure of liquid desiccant decreases with increasing concentration. A characterization model of the saturated vapor pressure reduction rate is established, and the intrinsic relationship between the Dp and dehumidification performance is clarified. From the perspective of microscopic interactions, the mechanism by which ions bind to water molecules is revealed, demonstrating that ion-water molecule dipole interactions are the primary factor influencing the Dp of the liquid desiccant solution. Higher ionic charge or smaller ionic radius lead to stronger dipole interactions, thereby increasing this rate. The quantitative Dp of ions indicates that charge-dense divalent ions (Mg2+, Ca2+) elevate vapor suppression efficiency by >77 % versus Li+ systems. Furthermore, an regulation method for increasing Dp is proposed. Finally, through a series of experimental cases, the regulation method proposed in this paper guides how to reduce the saturated vapor pressure of liquid desiccant and promot air deep dehumidification, and points out the direction for ionic structure design of liquid desiccant material in the future.