A current efficiency model coupled with desiccant molecular weight for electrodialysis regeneration in liquid desiccant air-conditioning systems

Abstract

Liquid desiccant air-conditioning system is an energy-efficient choice for heat and moisture independent treatment in buildings, especially for the large dehumidification load. Electrodialysis regeneration is a novel and reliable regeneration method for liquid desiccants, which is suitable for hot and humid climates. In this paper, the performance of the electrodialysis regenerator for regenerating lithium chloride and lithium bromide solutions was studied experimentally, and the current efficiency of the electrodialysis regenerator for regenerating these two solutions was compared. Through analysis, the solute molecular weight was coupled into the current efficiency model, and a new current efficiency model of electrodialysis regenerator for regenerating these two solutions was established, which considers the solute molecular weight of liquid desiccant and can be extended to more liquid desiccants in the future. Furthermore, the performance of the liquid desiccant air-conditioning system using electrodialysis regeneration with these two solutions is compared based on this model. The results show that when lithium chloride solution is applied as liquid desiccant, the system performance coefficient (COP, ratio of cooling capacity to energy consumption) is between 1.16 and 4.49, while the performance coefficient of the system is between 2 and 8.3 when the system uses lithium bromide solution.