Investigation of falling-film plate wettability characteristics under dehumidification and regeneration conditions using LiCl-H2O

Liquid desiccant air conditioning system has unique advantages and prospects in both humidity control and low-grade heat driven cooling. The liquid film wettability is one of the significant factors governing the efficiency of dehumidification/regeneration processes in the system. In this paper, the effect of the LiCl solution properties on falling-film plate wettability characteristic is studied using a VOF method. This paper analyzes the dehumidification and regeneration processes respectively and gets the recommended amount of spray, which was 0.619 m3/(m·h) for dehumidification and 0.662 m3/(m·h) for regeneration. The recommended amount of spray can not only ensure the full-film flow, but also avoid the excessive solution flow rate which may increase the possibility of droplets entrainment. Since the wettability is determined by the coupled effects of the solution density, viscosity and surface tension, the effects of dynamic properties of liquid desiccant on the wettability are studied to explain the influence of the solution temperature and concentration on the wettability. Finally, least squares method is used to fit a formula to describe the effect of solution properties on falling-film plate wettability, which can guide the control of the amount of spray in actual operation.