Regeneration performance of liquid desiccant on the surface of a plate-type heat exchanger

Recently, there have been many studies on dehumidifiers with a low flow rate of liquid desiccant, in which a plate-type heat exchanger with internal cooling is adopted. If the low flow rate of a liquid desiccant maintains a thin liquid film on the heat exchanger surface, heat and mass transfer performance would improve, the stability of the liquid film would increase, and there would be no entrainment of desiccant droplets. In this study, we built an experimental apparatus to measure the regeneration performance of a liquid desiccant and investigated the wettability of the liquid desiccant along the vertical surface of a plate-type heat exchanger. Liquid desiccant was applied to the top of plate heat exchangers having different groove gaps, on which we had applied a hydrophilic coating to enhance the wettability of the liquid desiccant. In a visualization test, we found that a plate heat exchanger with a 1.0-mm groove gap resulted in the greatest wettability. As the mass flow rate of the supplied liquid desiccant increases, the wettability of the liquid desiccant is enhanced, and the regeneration rate and mass transfer coefficient can also be enhanced. We developed experimental correlations for the heat and mass transfer performances of the heat exchanger.