Ammonia absorption performance of a liquid desiccant dehumidification system applied in laboratory rodent room

Abstract

• Henry’s law constant of ammonia in common liquid desiccants is investigated. • The ammonia transfer model in pack modules of liquid desiccant system is proposed. • Liquid desiccant dehumidification system with LiBr solution is verified to get better ammonia performance than other desiccants. • The improved system significantly decreases the ammonia concentration of supply air compared to regular liquid desiccant dehumidification system. Laboratory rodent room usually adopts full fresh air system with large ventilation rates and causes energy waste for heat-cold offset process. Liquid desiccant system is identified as an energy saving approach in humidity control field. This paper presents the ammonia absorption performance of a liquid desiccant dehumidification system applied in laboratory rodent room while considering air dehumidification requirements. Prior to the simulation process of the system, Henry’s law constant ( H C ) of ammonia, one method to assess the solubility, in LiBr, LiCl, and CaCl 2 solutions are tested at the salt concentration range of 20–50 wt% and at the temperature range of 10–50 °C. The ammonia concentration of supply air ( C sa ) in the LiBr condition is apparently smaller than that in LiCl and CaCl 2 conditions of a liquid desiccant dehumidification system. In addition, C sa apparently increases with the increasing number of mass transfer units of ammonia ( NTU a ) and solution flow rate. The simulation results show that most ammonia is introduced by heat recovery process. An improved system structure is proposed to reduce ammonia transfer. Using the proposed heat recovery method, C sa is decreased by more than 70% over the initial system.