Experiments on a vapor compression air conditioner with liquid desiccants for efficient dehumidification

Woods, Jason; Shoukas, Greg; Lu, Zechao; Kozubal, Eric

doi:10.1016/j.enconman.2025.120683

Experiments on a vapor compression air conditioner with liquid desiccants for efficient dehumidification

Journal Article · Tue Oct 28 00:00:00 EDT 2025 · Energy Conversion and Management

DOI:https://doi.org/10.1016/j.enconman.2025.120683· OSTI ID:3014852

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National Renewable Energy Laboratory (NREL), Golden, CO (United States)

Buildings require air conditioning systems that not only cool and dehumidify supply air but also provide sufficient ventilation to ensure indoor air quality and occupant comfort. However, standard recirculation systems-which introduce about a 10 % to 20 % fraction of outdoor air-often fail to deliver air that is precisely cooled and dry, particularly because 80-90 % of the ventilation cooling load is latent. Mixing humid ventilation air with recirculated indoor air increases the energy and costs required to condition the air to comfortable levels. Dedicated outdoor air systems (DOASs) are designed to handle this latent dominated ventilation load and thus need to have efficient humidity removal. Many cooling cycles can perform this task. Here we describe a liquid desiccant DOAS, which combines a vapor compression cycle and a liquid desiccant absorber and desorber pair. We present its performance at 26 operating conditions and a thermodynamic model which can accurately predict the moisture removal efficiency. The model's performance predictions have a mean percentage error of 2.5 % and a coefficient of variation of the root mean square error of 7.5 %. We also compare the performance of this vapor-compression-coupled liquid desiccant system with a standard vapor compression system with the same components but no liquid desiccant. For the 26 conditions tested in this study, this comparison shows that adding liquid desiccants lowers the required evaporator cooling load by 21 %, allows for 25 % lower compressor volumetric capacity, and 25 % lower electricity use. Future work will leverage this model to quantify the reduction in annual electricity use across different climates, including the need for a standard vapor compression system to reheat the air during some of the year.

View Accepted Manuscript (DOE)

Research Organization:: National Laboratory of the Rockies (NLR), Golden, CO (United States)

Sponsoring Organization:: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Energy Efficiency Office. Building Technologies Office

Grant/Contract Number:: AC36-08GO28308

OSTI ID:: 3014852

Report Number(s):: NLR/JA--5500-95359

Journal Information:: Energy Conversion and Management, Journal Name: Energy Conversion and Management Vol. 348; ISSN 0196-8904

Publisher:: ElsevierCopyright Statement

Country of Publication:: United States

Language:: English

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32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
dedicated outdoor air system
dehumidification
liquid desiccant

Experiments on a vapor compression air conditioner with liquid desiccants for efficient dehumidification

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