Counter-Crossflow Indirect Evaporative Cooling-Assisted Liquid Desiccant Dehumidifier : Model Development and Parameter Analysis

Using auxiliary internal cooling is an effective way to improve the dehumidification effectiveness of the liquid desiccant dehumidifier (LDD) compared with the adiabatic dehumidifier. Indirect evaporative cooling (IEC) is a promising solution for internal cooling owing to its high efficiency and environmentally friendly features. To ensure efficient heat transfer and facilitate easy installation simultaneously, a hexagonal plate heat exchanger (PHE) consisting of both counter flow and crossflow was used as a core in an IEC-assisted LDD. A numerical model of heat and mass transfer was established and validated, and intensive parameter analysis on the thermal performance of the dehumidifier was conducted. The influential parameters include inlet primary air conditions (temperature, humidity, and velocity), inlet solution conditions (temperature, mass flow rate, and concentration), secondary to primary airflow ratio, the geometry of heat exchanger, channel gap, and the wetness coefficient of the solution. Simulation results show that the auxiliary internal IEC cooling enhances the dehumidification effectiveness by 16% compared to an adiabatic dehumidifier. The primary air velocity has the greatest impact on the LDD performance. The dehumidification effectiveness is reduced by 23% as the primary air inlet velocity decreases from 4.5 m/s to 0.5 m/s