Research on the performance of tube internally-cooled falling film dehumidifier based on CFD

The dehumidifier is the core component of a liquid desiccant dehumidification system. To investigate the heat and mass transfer characteristics of internally-cooled tube falling film dehumidifiers and the factors affecting their performance, this study established a 2D dehumidifier model using CFD technology. The accuracy of the model was validated by comparing it with experimental and simulation data from the literature. Subsequently, the transient flow characteristics and dynamic changes in temperature and humidity within the tube were analyzed, along with the influence of various operating parameters on the dehumidifier's performance. The transient research results show that the velocity of the solution remains basically constant when flowing along the tube wall, and the absolute moisture removal (AMR) when the solution reaches the bottom of the dehumidification tube is 96.1 % of that under stable dehumidification conditions.The steady-state research results show that the absolute dehumidification amount during isothermal dehumidification is 32 % higher than that during adiabatic dehumidification. The inlet air temperature and solution flow rate have a relatively small impact on the dehumidification effect of the internally cooled dehumidifier. When the inlet air temperature rises by 10 °C and the solution flow rate increases by 33.3 %, the absolute dehumidification amount only increases by 6.5 % and 3.2 % respectively. The solution temperature and concentration have a greater impact on the dehumidification performance. This dehumidifier has significant advantages at low solution flow rates and when dealing with high-temperature and high-humidity air. The research results of this study will provide a reference for the practical application of dehumidifiers in high-temperature and high-humidity environments.