Comparison of Dehumidification Performance of A Single and Two Stage Dehumidifiers In a Liquid Desiccant-Assisted Dedicated Outdoor Air System

Abstract

The aim of this study is to investigate the dehumidification performance and energy conservation of a two-stage liquid desiccant dehumidifier and a single-stage dehumidifier. To enhance the dehumidification performance, a cascade liquid desiccant (CLD) system was applied in an outdoor air unit to adjust the target humidity condition of the induced outdoor air. The CLD consists of a two-stage liquid desiccant dehumidifier unit to carry out deep dehumidification of process air. Process air is dehumidified twice by the CLD system to improve the dehumidification performance of process air compared to a single dehumidifier. The single and cascade liquid desiccant systems were integrated with water-side free cooling using cooling towers for desiccant solution cooling. The energy consumption performance of both systems was evaluated through simulation when operating in an office space as a dedicated outdoor air system (DOAS). The thermal load of a model office space was estimated using TRNSYS 17, and the cooling coil load of DOAS was predicted using a commercial equation solver program. The results show that compared to a single dehumidifier system, CLD requires a lower cooling coil load.