Numerical Performance Evaluation of Aqueous LiCl and CaCl₂ Solutions as Liquid Desiccants in Dehumidification Systems

In tropical countries like Indonesia, humidity levels are generally high, with relatively constant temperatures. This explanation emphasizes that in a room, the responsibility of regulating humidity and air temperature to ensure comfort is significant. To control the amount of water vapor, the dehumidification process can be carried out using liquid desiccants. The purpose of this research is to test the system scheme and types of liquid desiccants used to enhance air quality by reducing humidity. This study aims to determine the transfer performance of aqueous LiCl and CaCl₂ liquid desiccants by numerical means, including the process of reducing water content in the air via the absorption of water content in the air by the liquid desiccant, and the heat and mass transfer phenomena that occur with the liquid desiccants. The research is conducted numerically by simultaneously solving heat and mass transfer equations using the finite difference method explicitly, with the changes in property values of the liquid desiccant in each control volume. The results indicate that comparisons with experimental values show an error of less than 5%. The differences in fluid characteristics and property values between the aqueous LiCl and CaCl₂ solution remarkably affect the reduction water content from the air. The performance of an aqueous LiCl solution with a concentration of 40% (wt. of LiCl) in absorbing water vapor from the air is better than that of the aqueous CaCl₂ solution. When using the CaCl₂ solution, performance decreases by 15% compared to the LiCl solution. During the process of absorbing water vapor from the air, the liquid desiccant undergoes an exothermic reaction, leading to an increase in the temperature of the liquid desiccant of around 13%. Apart from performance, considering the corrosive nature of LiCl and the relatively cheaper price of CaCl₂, CaCl₂ can be considered a fairly reliable alternative liquid desiccant.