Thermodynamics Research Center / ThermoML | Thermochimica Acta

Concentration dependent melting enthalpy, crystallization velocity, and thermal cycling stability of pinacone hexahydrate

Rathgeber, Christoph, Grisval, Alexis, Schmit, Henri, Hoock, Peter, Hiebler, Stefan
Thermochim. Acta 2018, 670, 142-147
ABSTRACT
Pinacone hexahydrate, a glycol hydrate, has a comparably high melting enthalpy of about (316 +- 16) J*g-1 at 45.5 deg.C. Based on results of a previous study and to further assess the applicability of pinacone hexahydrate to be used as phase change material in latent heat storage systems, additional investigations were carried out in this work. First, the influence of a deviation of the water content around the stoichiometric hexahydrate composition on the melting enthalpy was investigated. It was less pronounced compared with typical inorganic salt hydrates. Second, the crystallization velocity was measured as a function of temperature with a maximum value of about 0.5 cm*min-1 at 27 deg.C. Third, tests of the thermal cycling stability were carried out. Within 110 conducted cycles between 20 deg.C and 60 deg.C, the melting enthalpy and temperature remained stable.
Compounds
# Formula Name
1 C6H14O2 2,3-dimethyl-2,3-butanediol
2 H2O water
3 C6H26O8 pinacone hexahydrate
Datasets
The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type Compound-# Property Variable Constraint Phase Method #Points
  • POMD
  • 3
  • Normal melting temperature, K ; Crystal
  • Crystal
  • Liquid
  • Air at 1 atmosphere
  • DTA
  • 1
  • POMD
  • 3
  • Molar enthalpy of transition or fusion, kJ/mol ; Crystal
  • Crystal
  • Liquid
  • Air at 1 atmosphere
  • DSC
  • 1
  • POMD
  • 1
  • 2
  • Solid-liquid equilibrium temperature, K ; Liquid
  • Mass fraction - 2; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Crystal of intercomponent compound 2
  • DTA
  • 4