Enhancing the falling film dehumidification performance from the prospective of CFD simulation

Abstract

Further enhancing the dehumidification performance of liquid desiccant cooling system helps to get higher energy efficiency and better system performance. Previous studies mainly focused on experimental exploration of enhancement methods, such as surface modification and additives addition, which were greatly restricted by its huge investment and complexity. CFD technology provides an alternative approach to explore the coupled hydrodynamics, heat and mass characteristics in various areas with great flexibility and convenience. Based on our previously developed 3D simulation model, the present study put forward some dehumidification performance enhancement methods and explored the corresponding enhancement mechanism from the prospective of CFD technology for the first time. After further validation of the model by film dynamics, the influences of channel gap and gas-solution flow patterns on mass transfer performance were identified. Then, the effectiveness of various enhancement methods, including internal cooling, super-hydrophilic coating, curved surface and coated plate with fin structures, were comprehensively examined and analyzed. Results revealed that the cross flow configuration had the highest moist removal performance with an distinct improvement of 46.2% and flowed by countercurrent flow with an 30.8% improvement compared with current flow. The proposed approaches could all enhance the dehumidification performance with different degrees ranging from 7.8% to 47.1%. The highest enhancement occurred on the super-hydrophilic plate with curved fin, which was caused by the enlargement of wetting area and structure induced flow mixture. The present study provides some potential approaches and a promising way for the development of high efficiency heat and mass transfer components.