Print Email Facebook Twitter Understanding the Hydration Process of Salts: The Impact of a Nucleation Barrier Title Understanding the Hydration Process of Salts: The Impact of a Nucleation Barrier Author Sogütoglu, L.C. Steiger, M. Houben, J. Biemans, D. Fischer, H.R. Donkers, P.A.J. Huinink, H. Adan, O.C.G. Publication year 2019 Abstract The solid-state hydration of salts has gained particular interest within the frame of thermochemical energy storage. In this work, the water vapor pressure-temperature (p-T) phase diagram of the following thermochemical salts was constructed by combining equilibrium and nonequilibrium hydration experiments: CuCl 2 , K 2 CO 3 , MgCl 2 ·4H 2 O, and LiCl. The hydration of CuCl 2 and K 2 CO 3 involves a metastable zone of ca. 10 K, and the induction times preceding hydration are well-described by classical homogeneous nucleation theory. It is further shown for K 2 CO 3 (metastable) and MgCl 2 ·4H 2 O (not metastable) through solubility calculations that the phase transition is not mediated by bulk dissolution. We conclude that the hydration proceeds as a solid-solid phase transition, mobilized by a wetting layer, where the mobility of the wetting layer increases with increasing vapor pressure. In view of heat storage application, the finding of metastability in thermochemical salts reveals the impact of nucleation and growth processes on the thermochemical performance and demonstrates that practical aspects like the output temperature of a thermochemical salt are defined by its metastable zone width (MZW) rather than its equilibrium phase diagram. Manipulation of the MZW by e.g. prenucleation or heterogeneous nucleation is a potential way to raise the output temperature and power on material level in thermochemical applications. © Copyright 2019 American Chemical Society. Subject Copper compoundsHeat storageHydrationHydrostatic pressureLithium compoundsMagnesium compoundsNucleationPhase diagramsPotashSaltsWettingEquilibrium phase diagramsHeterogeneous nucleationHomogeneous nucleationMetastable zone widthNucleation and growthSolid-solid phase transitionsSolubility calculationsThermochemical energy storageChlorine compounds To reference this document use: http://resolver.tudelft.nl/uuid:8bbc10e3-43a4-44fc-a818-63e6af9f666e TNO identifier 866585 Publisher American Chemical Society ISSN 1528-7483 Source Crystal Growth and Design, 19 (4), 2279-2288 Document type article Files To receive the publication files, please send an e-mail request to TNO Library.