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Water activity and sorption thermodynamics of H2O/[EMIM][MeSO3] and H2O/Betaine:Glycerol from experimental Vapor-Liquid Equilibrium data.

Auteurs : WERNHART M., RIEBERER R., WEINZETTI C., KIENBERGER M., DAMN M.

Type d'article : Article de la RIF

Résumé

Absorption heat pumps (AHPs) are a valuable technology for efficiently utilizing waste heat, e.g. from industrial processes. The common working pair H2O/LiBr is favored due to the high latent heat of water, its low saturation pressures and the water affinity of LiBr. However, LiBr as a sorbent can cause problems such as corrosion and crystallization, especially at high LiBr mass fractions, which usually occur at high desorber temperatures. To address these issues, alternative sorbents such as ionic liquids and deep eutectic solvents, compatible with water as a refrigerant, have recently gained attention. In this contribution, the thermodynamic characteristics of two novel water-based working pairs (H₂O/[EMIM] [MeSO₃] and H₂O/betaine:glycerol) are compared using experimentally determined vapor-liquid equilibrium data covering the operating range of high-temperature AHPs (solution temperatures between ≈ 50 ◦C and ≈ 180 ◦C; vapor pressures between ≈ 20 mbar and ≈ 1.5 bar). The data is used to determine the corresponding water activities and to derive a correlation for their calculation. This correlation is further used to compare the sorbents
in a Clausius–Clapeyron-type representation. In addition, the sensitivity of the sorption equilibrium and viscosity-weighted mass-transport indicators are assessed. The approach presented provides a framework for evaluating novel working fluids and facilitates their direct comparison with respect to both thermodynamic driving forces and viscosity-limited mass transfer. The results demonstrate that H₂O/[EMIM][MeSO₃] exhibits lower water activities, indicating stronger binding of water as well as elevated sensitivity, compared to H₂O/betaine:glycerol. Consequently, the sorption potential is consistently higher for the ionic liquid over the entire composition range. This advantage is further enhanced by the lower viscosity of H₂O/[EMIM][MeSO₃] compared with H₂O/betaine:glycerol, resulting in significantly better mass-transport behavior.

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Pages : 13 p.

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  • Titre original : Water activity and sorption thermodynamics of H2O/[EMIM][MeSO3] and H2O/Betaine:Glycerol from experimental Vapor-Liquid Equilibrium data.
  • Identifiant de la fiche : 30035321
  • Langues : Anglais
  • Sujet : Technologie
  • Source : International Journal of Refrigeration - Revue Internationale du Froid - vol. 190
  • Date d'édition : 10/2026
  • DOI : http://dx.doi.org/https://doi.org/10.1016/j.ijrefrig.2026.107060

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