Vapour pressures and densities of the mixed-solvent desiccants (glycols + water + salts)

The vapour pressures and densities of the mixed-solvent desiccants have been studied for temperatures ranging from (303.15 to 343.15) K. The mixed-solvent desiccants investigated were aqueous-organic systems with salt. The studied organic solvents were diethylene glycol, tetraethylene glycol, and dipropylene glycol. The chosen salts were lithium chloride and lithium bromide. Six ternaries (glycol/water/salt) were selected for this study. For each ternary system, four systems of which (4–25) mass% salt mixed with various glycols (50–80) mass% were investigated. Incorporated with the pseudo-solvent approach, a vapour pressure model based on the mean spherical approximation for aqueous electrolyte solutions was used to represent the measured vapour pressure of glycol/water/salt systems. A simplified density equation was applied to model the measured density of glycol/water/salt systems. Satisfactory results were obtained for vapour pressure and density calculations. The vapour pressures of the aqueous-organic systems with salt yield smaller values of vapour pressures compared to the conventionally used liquid desiccants. The properties obtained and presented in this study are, in general, of sufficient accuracy for most engineering-design calculations, such as the design of dehumidifier process using mixed-solvent desiccants as absorbents.