Performance comparison of three typical types of internally-cooled liquid desiccant dehumidifiers

Numerous types of internally-cooled liquid desiccant dehumidifiers have been proposed in recent studies. In the present study, detailed quantitative comparisons of three typical types of internally-cooled dehumidifiers with different structures (parallel plate, fin coil, and packed tower with cooling tubes) were performed. The heat and mass transfer coefficients and the specific surface areas of the different types of devices were compared and a heat and mass transfer model of an internally-cooled dehumidifier was adopted to analyze the performance of different devices. The results showed that internally-cooled dehumidifier with the fin-coil structure demonstrated superior performance compared to the other two systems; the packed tower with cooling tubes displayed the poorest performance among the three devices. In addition, the effects of the heat transfer ability between the desiccant and cooling water and the mass transfer ability between the desiccant and air on dehumidification performance were investigated. Results showed that the main reason for the difference in performance is that mass transfer ability influenced current device performance to the greatest degree. Thus, to further improve the devices, greater attention should be paid to the mass transfer process between the air and desiccant.