Analytical model for characterizing mass transfer of volatile organic compounds in internally-cooled liquid desiccant dehumidifiers

Volatile organic compounds (VOCs) in indoor air pose a significant hazard to human health, owing to their potential associated chronic and acute health risks. Liquid dehumidification has emerged as a promising technology for eliminating indoor VOCs. However, the studies on the mass transfer behavior of VOCs in dehumidifiers are mainly confined to experimental and numerical methods, which are both time-consuming and labor-intensive. In contrast, analytical methods are more attractive and advantageous in solving these problems. Therefore, in the present study, we propose an analytical model to quantify the mass transfer behavior of VOCs in an internally-cooled dehumidifier. To confirm the broad applicability of the proposed model, both the hydrophilic and hydrophobic properties of VOCs were considered. Formaldehyde and benzene were selected as two typical representatives. The reliability of the proposed model was demonstrated by investigating the VOC transfer characteristics and removal performance as the key factors varied. It was found that the analytical results agree well with the published numerical results. With variation of the key parameters, the trends of the VOC removal performance obtained by the analytical and numerical methods are basically in agreement. The analytical model can not only effectively describe the mass transfer characteristics of VOCs, but also adequately determine the VOCs removal performance. Moreover, the analytical model shows a wide-range response to different VOCs, with the order of Henry's law constant ranging from 10-5 to 10-3. For both hydrophilic formaldehyde and hydrophobic benzene, the deviations do not exceed +/- 10 %. This study provides an intuitive and labor-saving method to evaluate VOC removal using internally-cooled dehumidifiers.