Performance enhancement analysis of a liquid desiccant dehumidifier with internal cooling for indoor benzene removal

Abstract

Indoor volatile organic compounds (VOCs) pollution is becoming increasingly serious, posing a huge threat to human health. The removal of VOCs has always been a challenge in air purification processes. In this regard, conventional VOC removal methods are often not ideal. Liquid desiccant (LD) dehumidification is a new removal method proposed recently and becoming increasingly used in many applications. Previous studies dealing with LD mainly focused on adiabatic dehumidifiers, but the results are not very promising. The main reason for this is the significant temperature rise of the LD solution, which seriously affects the mass transfer of the VOC. To enhance mass transfer performance, it is important to suppress temperature rise. In this study, internal cooling (IC) technology is introduced to enhance benzene mass transfer. A mathematical model is established for modeling and assessing the mass transfer process. The benzene transfer characteristics are studied and compared, considering dehumidifiers with and without IC. The effects of the cooling water, air, LD solution, and transfer parameters on the benzene mass transfer performance are evaluated and identified. Additionally, the distribution differences of the key parameters along the dehumidifier are revealed. The results indicated that benzene transfer performance can be significantly enhanced by adopting IC, with a performance improvement of 28.42%. This improvement is attributed to the decrease in the LD solution temperature caused by IC and the corresponding Henry’s constant. The cooling water parameters, airflow rate, LD solution status, and NTUbenzene are the key factors affecting the removal performance. Overall, employing IC can effectively improve the transfer driving force for benzene, resulting in better benzene transfer performance. This study demonstrates the feasibility and promising potential of using IC technology to enhance benzene transfer in LD dehumidifiers.