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Experimental investigation of a liquid desiccant system for air dehumidification working with ionic liquids

Zegenhagen, Mark T.; Ricart, Cristina; Meyer, Thomas; Kühn, Roland; Ziegler, Felix

Electrically-driven compression chillers are the commonly used technology for cooling and dehumidifying air. Open sorption systems driven by solar heat are an alternative to conventional air dehumidification technology and may reduce primary energy consumption. For air dehumidification, liquid desiccant systems may exhibit some process engineering and thermodynamic advantages in comparison to solid desiccant systems. The liquid desiccant must exhibit low equilibrium water vapour pressures at the available heat rejection temperature level to achieve low air dew point temperatures and thus a strong air dehumidification with comparably low driving temperatures. Desiccant mass fractions should be as low as possible, but in order to achieve low vapour pressures required desiccant mass fractions may surpass the solubility limit. In the paper at hand, first experimental results of an internally cooled and heated, open liquid desiccant system working with an ionic liquid designed for air dehumidification are presented. It is demonstrated that ionic liquids designed according to the boundary conditions of the respective application may be a promising alternative to commonly used desiccants such as lithium chloride for solar air dehumidification with comparably high heat rejection and low driving temperatures.
Published in: Energy Procedia, 10.1016/j.egypro.2015.02.159, Elsevier