Mathematical modelling and simulation analysis of electrodialysis regeneration for LiCl liquid desiccant air conditioning systems

The regeneration process is crucial to guarantee continuous dehumidification in liquid desiccant air conditioning systems. Electrodialysis (ED) is recently considered as an alternative solution to assist in regenerating liquid desiccants. This paper presents the mathematical modelling of mass transfer and electrical energy consumed by the ED stack for regenerating liquid desiccant by taking into account the effect of solution concentration and current density on the characteristics of membrane pairs. The model was validated using the data collected from the experiments. Based on which, simulations were conducted to examine how the design and operating parameters affect the regeneration performance of ED using the proposed mathematical model. It was found that the concentration increase per unit power consumption was lower with a larger effective area of one membrane pair and a larger number of membrane pairs. When the inlet concentration of the regenerated solution was below 28% (wt ⋅ wt⁻¹), the concentration increase of the regenerated solution decreased with an elevation in the solution concentration at the inlet of the regenerated channel. When the inlet concentration of the regenerated solution was above 28% (wt ⋅ wt⁻¹), the concentration increase of the regenerated solution elevated with an increase in the solution concentration at the inlet of the regenerated channel.