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Determination of structural, thermodynamic and phase properties in the NA2S-H2O system for application in a chemical heat pump
Gepubliceerd door: Publicatie datum:
ECN Energie Efficiency in de Industrie 1-3-2002
ECN publicatienummer: Publicatie type:
ECN-RX--02-009 Artikel wetenschap tijdschrift
Aantal pagina's:

Gepubliceerd in: The paper is to be published in: Thermochimica Acta (Jan. 3003) (), , , Vol., p.-.

Structural, thermodynamic and phase properties in the Na2S-H2O systemfor application in a chemical heat pump have been investigated using XRD, TG/DTA and melting point and vapour pressure determinations. Apart from the known crystalline phases Na2S-9H2O, Na2S-5H2O and Na2S a new phase Na2S-2H2O has been proven to exist. Na2S-½H2O is not a phase but a 3:1 mixture of Na2S and Na2S-2H2O, presumably stabilised by very slow dehydration kinetics. The vapour pressure-temperature equilibria of the sodium sulphide hydrates have been determined and a consistent set of thermodynamic functions for these compounds has been derived. XRD measurements indicate the topotactic character of the transitions between the hydration states.

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