Investigating dehumidification performance of solar-assisted liquid desiccant dehumidifiers considering different surface properties

Abstract

Solar-assisted liquid desiccant dehumidification is promising regarding its lower energy consumption. Surface properties of dehumidifiers critically influence the dehumidification performance. Therefore, this paper aims at investigating the influence of surface properties on dehumidification performance of falling film dehumidifiers. Three commonly-used plate dehumidifiers, i.e., Stainless steel plate dehumidifier, Titanium plate dehumidifier and Polytetrafluoroethylene plate dehumidifier, with distinctive surface properties were chosen for study. Surface free energy was measured to characterize the adhesion between liquid desiccant and solid surface. Then, the effect of surface properties on dehumidification performance was experimentally investigated. The experimental results indicated that surface wettability demonstrated positive effect on dehumidification performance by increasing wetting area and reducing falling film thickness. As surface free energy increased from 30.34 mJ/m2 to 50.61 mJ/m2, the moisture removal rate increased from 0.155 to 0.213 with the enhancing ratio of 37.4%. A novel mass transfer correlation was developed, among which surface free energy was introduced to consider the effect of surface properties on dehumidification performance. It is estimated that 9.6% of the energy consumption could be saved by improving surface wettability of falling film dehumidifiers. This research is also very useful to other falling film applications, such as evaporators, condensers and chemical columns.